Programs & Examples On #Calendar

A calendar is a system of reckoning time in which the beginning, length and divisions of a year are defined. The term may refer to a software class or library for the manipulation and display of calendar data, or to a list of events with associated dates and times, managed by a human via an application or operating system user interface.

Java: Get month Integer from Date

If you can't use Joda time and you still live in the dark world :) ( Java 5 or lower ) you can enjoy this :

Note: Make sure your date is allready made by the format : dd/MM/YYYY

Make an int Month from a date
public static int getMonthInt(Date date) {

    SimpleDateFormat dateFormat = new SimpleDateFormat("MM");
    return Integer.parseInt(dateFormat.format(date));

Make an int Year from a date
public static int getYearInt(Date date) {

    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy");
    return Integer.parseInt(dateFormat.format(date));

Creating java date object from year,month,day

Make your life easy when working with dates, timestamps and durations. Use HalDateTime from

For example you can just use it to parse your input like this:

HalDateTime mydate = HalDateTime.valueOf( "25.12.1988" );
System.out.println( mydate );   // will print in ISO format: 1988-12-25

You can also specify patterns for parsing and printing.

Get first date of current month in java

First day of month of a date:

public static Date firstDayOfMonth(Date d) {
    Calendar calendar = new GregorianCalendar();
    calendar.set(Calendar.DAY_OF_MONTH, 1);
    return calendar.getTime();  

How to subtract X day from a Date object in Java?

Java 8 Time API:

Instant now =; //current date
Instant before = now.minus(Duration.ofDays(300));
Date dateBefore = Date.from(before);

How to add minutes to my Date

This is incorrectly specified:

SimpleDateFormat df = new SimpleDateFormat("yyyy-mm-dd HH:mm");

You're using minutes instead of month (MM)

How to set time to a date object in java

Can you show code which you use for setting date object? Anyway< you can use this code for intialisation of date:

new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").parse("2011-01-01 00:00:00")

Why Java Calendar set(int year, int month, int date) not returning correct date?

Months in Calendar object start from 0

0 = January = Calendar.JANUARY
1 = february = Calendar.FEBRUARY

How to get complete month name from DateTime



With 4 Ms.

Calendar Recurring/Repeating Events - Best Storage Method

@Rogue Coder

This is great!

You could simply use the modulo operation (MOD or % in mysql) to make your code simple at the end:

Instead of:

    ( CASE ( 1299132000 - EM1.`meta_value` )
        WHEN 0
          THEN 1
        ELSE ( 1299132000 - EM1.`meta_value` )
    ) / EM2.`meta_value`
) = 1


$current_timestamp = 1299132000 ;

AND ( ('$current_timestamp' - EM1.`meta_value` ) MOD EM2.`meta_value`) = 1")

To take this further, one could include events that do not recur for ever.

Something like "repeat_interval_1_end" to denote the date of the last "repeat_interval_1" could be added. This however, makes the query more complicated and I can't really figure out how to do this ...

Maybe someone could help!

How do I localize the jQuery UI Datepicker?

If you use jQuery UI's datepicker and moment.js on the same project, you should piggyback off of moment.js's locale data:

// Finnish. you need to include separate locale file for each locale:

// fetch locale data internal structure, so we can shove it inside jQuery UI
var momentLocaleData = moment.localeData(); 

$.datepicker.regional['user'] = {
    monthNames: momentLocaleData._months,
    monthNamesShort: momentLocaleData._monthsShort,
    dayNames: momentLocaleData._weekdays,
    dayNamesShort: momentLocaleData._weekdaysMin,
    dayNamesMin: momentLocaleData._weekdaysMin,
    firstDay: momentLocaleData._week.dow,
    dateFormat: 'yy-mm-dd' // "2016-11-22". date formatting tokens are not easily interchangeable between momentjs and jQuery UI (


Display calendar to pick a date in java

I wrote a DateTextField component.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Frame;
import java.awt.GridLayout;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JTextField;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.border.LineBorder;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class DateTextField extends JTextField {

    private static String DEFAULT_DATE_FORMAT = "MM/dd/yyyy";
    private static final int DIALOG_WIDTH = 200;
    private static final int DIALOG_HEIGHT = 200;

    private SimpleDateFormat dateFormat;
    private DatePanel datePanel = null;
    private JDialog dateDialog = null;

    public DateTextField() {
        this(new Date());

    public DateTextField(String dateFormatPattern, Date date) {
        DEFAULT_DATE_FORMAT = dateFormatPattern;

    public DateTextField(Date date) {
        setCursor(new Cursor(Cursor.HAND_CURSOR));

    private void addListeners() {
        addMouseListener(new MouseAdapter() {
            public void mouseClicked(MouseEvent paramMouseEvent) {
                if (datePanel == null) {
                    datePanel = new DatePanel();
                Point point = getLocationOnScreen();
                point.y = point.y + 30;
                showDateDialog(datePanel, point);

    private void showDateDialog(DatePanel dateChooser, Point position) {
        Frame owner = (Frame) SwingUtilities
        if (dateDialog == null || dateDialog.getOwner() != owner) {
            dateDialog = createDateDialog(owner, dateChooser);
        dateDialog.setLocation(getAppropriateLocation(owner, position));

    private JDialog createDateDialog(Frame owner, JPanel contentPanel) {
        JDialog dialog = new JDialog(owner, "Date Selected", true);
        dialog.getContentPane().add(contentPanel, BorderLayout.CENTER);
        dialog.setSize(DIALOG_WIDTH, DIALOG_HEIGHT);
        return dialog;

    private Point getAppropriateLocation(Frame owner, Point position) {
        Point result = new Point(position);
        Point p = owner.getLocation();
        int offsetX = (position.x + DIALOG_WIDTH) - (p.x + owner.getWidth());
        int offsetY = (position.y + DIALOG_HEIGHT) - (p.y + owner.getHeight());

        if (offsetX > 0) {
            result.x -= offsetX;

        if (offsetY > 0) {
            result.y -= offsetY;

        return result;

    private SimpleDateFormat getDefaultDateFormat() {
        if (dateFormat == null) {
            dateFormat = new SimpleDateFormat(DEFAULT_DATE_FORMAT);
        return dateFormat;

    public void setText(Date date) {

    public void setDate(Date date) {

    public Date getDate() {
        try {
            return getDefaultDateFormat().parse(getText());
        } catch (ParseException e) {
            return new Date();

    private class DatePanel extends JPanel implements ChangeListener {
        int startYear = 1980;
        int lastYear = 2050;

        Color backGroundColor = Color.gray;
        Color palletTableColor = Color.white;
        Color todayBackColor =;
        Color weekFontColor =;
        Color dateFontColor =;
        Color weekendFontColor =;

        Color controlLineColor =;
        Color controlTextColor = Color.white;

        JSpinner yearSpin;
        JSpinner monthSpin;
        JButton[][] daysButton = new JButton[6][7];

        DatePanel() {
            setLayout(new BorderLayout());
            setBorder(new LineBorder(backGroundColor, 2));

            JPanel topYearAndMonth = createYearAndMonthPanal();
            add(topYearAndMonth, BorderLayout.NORTH);
            JPanel centerWeekAndDay = createWeekAndDayPanal();
            add(centerWeekAndDay, BorderLayout.CENTER);


        private JPanel createYearAndMonthPanal() {
            Calendar cal = getCalendar();
            int currentYear = cal.get(Calendar.YEAR);
            int currentMonth = cal.get(Calendar.MONTH) + 1;

            JPanel panel = new JPanel();
            panel.setLayout(new FlowLayout());

            yearSpin = new JSpinner(new SpinnerNumberModel(currentYear,
                    startYear, lastYear, 1));
            yearSpin.setPreferredSize(new Dimension(56, 20));
            yearSpin.setEditor(new JSpinner.NumberEditor(yearSpin, "####"));

            JLabel yearLabel = new JLabel("Year");

            monthSpin = new JSpinner(new SpinnerNumberModel(currentMonth, 1,
                    12, 1));
            monthSpin.setPreferredSize(new Dimension(35, 20));

            JLabel monthLabel = new JLabel("Month");

            return panel;

        private JPanel createWeekAndDayPanal() {
            String colname[] = { "S", "M", "T", "W", "T", "F", "S" };
            JPanel panel = new JPanel();
            panel.setFont(new Font("Arial", Font.PLAIN, 10));
            panel.setLayout(new GridLayout(7, 7));

            for (int i = 0; i < 7; i++) {
                JLabel cell = new JLabel(colname[i]);
                if (i == 0 || i == 6) {
                } else {

            int actionCommandId = 0;
            for (int i = 0; i < 6; i++)
                for (int j = 0; j < 7; j++) {
                    JButton numBtn = new JButton();
                    numBtn.addActionListener(new ActionListener() {
                        public void actionPerformed(ActionEvent event) {
                            JButton source = (JButton) event.getSource();
                            if (source.getText().length() == 0) {
                            int newDay = Integer.parseInt(source.getText());
                            Calendar cal = getCalendar();
                            cal.set(Calendar.DAY_OF_MONTH, newDay);


                    if (j == 0 || j == 6)
                    daysButton[i][j] = numBtn;

            return panel;

        private Calendar getCalendar() {
            Calendar calendar = Calendar.getInstance();
            return calendar;

        private int getSelectedYear() {
            return ((Integer) yearSpin.getValue()).intValue();

        private int getSelectedMonth() {
            return ((Integer) monthSpin.getValue()).intValue();

        private void dayColorUpdate(boolean isOldDay) {
            Calendar cal = getCalendar();
            int day = cal.get(Calendar.DAY_OF_MONTH);
            cal.set(Calendar.DAY_OF_MONTH, 1);
            int actionCommandId = day - 2 + cal.get(Calendar.DAY_OF_WEEK);
            int i = actionCommandId / 7;
            int j = actionCommandId % 7;
            if (isOldDay) {
            } else {

        private void reflushWeekAndDay() {
            Calendar cal = getCalendar();
            cal.set(Calendar.DAY_OF_MONTH, 1);
            int maxDayNo = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
            int dayNo = 2 - cal.get(Calendar.DAY_OF_WEEK);
            for (int i = 0; i < 6; i++) {
                for (int j = 0; j < 7; j++) {
                    String s = "";
                    if (dayNo >= 1 && dayNo <= maxDayNo) {
                        s = String.valueOf(dayNo);

        public void stateChanged(ChangeEvent e) {

            JSpinner source = (JSpinner) e.getSource();
            Calendar cal = getCalendar();
            if (source.getName().equals("Year")) {
                cal.set(Calendar.YEAR, getSelectedYear());
            } else {
                cal.set(Calendar.MONTH, getSelectedMonth() - 1);

How to convert Calendar to java.sql.Date in Java?

There is a getTime() method (unsure why it's not called getDate).

Edit: Just realized you need a java.sql.Date. One of the answers which use cal.getTimeInMillis() is what you need.

Convert String to Calendar Object in Java

No new Calendar needs to be created, SimpleDateFormat already uses a Calendar underneath.

SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy", Locale.EN_US);
Date date = sdf.parse("Mon Mar 14 16:02:37 GMT 2011"));// all done
Calendar cal = sdf.getCalendar();

(I can't comment yet, that's why I created a new answer)

Show week number with Javascript?

Simply add it to your current code, then call (new Date()).getWeek()

    Date.prototype.getWeek = function() {
        var onejan = new Date(this.getFullYear(), 0, 1);
        return Math.ceil((((this - onejan) / 86400000) + onejan.getDay() + 1) / 7);

    var weekNumber = (new Date()).getWeek();

    var dayNames = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
    var now = new Date();
    document.write(dayNames[now.getDay()] + " (" + weekNumber + ").");

Select current date by default in ASP.Net Calendar control

DateTime.Now will not work, use DateTime.Today instead.

How to add calendar events in Android?

if you have a given Date string with date and time .

for e.g String givenDateString = pojoModel.getDate()/* Format dd-MMM-yyyy hh:mm:ss */

use the following code to add an event with date and time to the calendar

Calendar cal = Calendar.getInstance();
cal.setTime(new SimpleDateFormat("dd-MMM-yyyy hh:mm:ss").parse(givenDateString));
Intent intent = new Intent(Intent.ACTION_EDIT);
intent.putExtra("beginTime", cal.getTimeInMillis());
intent.putExtra("allDay", false);
intent.putExtra("rrule", "FREQ=YEARLY");
intent.putExtra("endTime",cal.getTimeInMillis() + 60 * 60 * 1000);
intent.putExtra("title", " Test Title");

Check if a given time lies between two times regardless of date


20:11:13 < 01:00:00 < 14:49:00

LocalTime target = LocalTime.parse( "01:00:00" ) ;
Boolean targetInZone = ( 
    target.isAfter( LocalTime.parse( "20:11:13" ) ) 
    target.isBefore( LocalTime.parse( "14:49:00" ) ) 
) ; 


The java.time classes include LocalTime to represent a time-of-day only without a date and without a time zone.

So what I want is, 20:11:13 < 01:00:00 < 14:49:00.

First we define the boundaries. Your input strings happen to comply with standard ISO 8601 formats. The java.time classes use ISO 8601 formats by default, so no need to specify a formatting pattern.

LocalTime start = LocalTime.parse( "20:11:13" );
LocalTime stop = LocalTime.parse( "14:49:00" );

And define our test case, the target 01:00:00.

LocalTime target = LocalTime.parse( "01:00:00" );

Now we are set up to compare these LocalTime objects. We want to see if the target is after the later time but before the earlier time. That means middle of the night in this case, between approximately 8 PM and 3 AM the next morning.

Boolean isTargetAfterStartAndBeforeStop = ( target.isAfter( start ) && target.isBefore( stop ) ) ;

That test can be more simply stated as “not between 3 AM and 8 PM”. We could then generalize to any pair of LocalTime objects where we test for between if the start comes before the stop with a 24-hour clock, and not between if start comes after the stop (as in the case of this Question).

Further more, spans of time are usually handled with the Half-Open approach where the beginning is inclusive while the ending is exclusive. So a "between" comparison, strictly speaking, would be “is the target equal to or later than start AND the target is before stop”, or more simply, “is target not before start AND before stop”.

Boolean isBetweenStartAndStopStrictlySpeaking = 
    ( ( ! target.isBefore( start ) && target.isBefore( stop ) ) ;

If the start is after the stop, within a 24-hour clock, then assume we want the logic suggested in the Question (is after 8 PM but before 3 AM).

if( start.isAfter( stop ) ) {
    return ! isBetweenStartAndStopStrictlySpeaking ;
} else {
    return isBetweenStartAndStopStrictlySpeaking ;

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.

Where to obtain the java.time classes?

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

How to subtract X days from a date using Java calendar?

Taken from the docs here:

Adds or subtracts the specified amount of time to the given calendar field, based on the calendar's rules. For example, to subtract 5 days from the current time of the calendar, you can achieve it by calling:

Calendar calendar = Calendar.getInstance(); // this would default to now
calendar.add(Calendar.DAY_OF_MONTH, -5).

How to change TIMEZONE for a java.util.Calendar/Date

  1. The class Date/Timestamp represents a specific instant in time, with millisecond precision, since January 1, 1970, 00:00:00 GMT. So this time difference (from epoch to current time) will be same in all computers across the world with irrespective of Timezone.

  2. Date/Timestamp doesn't know about the given time is on which timezone.

  3. If we want the time based on timezone we should go for the Calendar or SimpleDateFormat classes in java.

  4. If you try to print a Date/Timestamp object using toString(), it will convert and print the time with the default timezone of your machine.

  5. So we can say (Date/Timestamp).getTime() object will always have UTC (time in milliseconds)

  6. To conclude Date.getTime() will give UTC time, but toString() is on locale specific timezone, not UTC.

Now how will I create/change time on specified timezone?

The below code gives you a date (time in milliseconds) with specified timezones. The only problem here is you have to give date in string format.

   DateFormat dateFormat = new SimpleDateFormat("yyyyMMdd HH:mm:ss");
   java.util.Date parsedDate = dateFormatLocal.parse(date);

Use dateFormat.format for taking input Date (which is always UTC), timezone and return date as String.

How to store UTC/GMT time in DB:

If you print the parsedDate object, the time will be in default timezone. But you can store the UTC time in DB like below.

        Calendar calGMT = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
        Timestamp tsSchedStartTime = new Timestamp (parsedDate.getTime());
        if (tsSchedStartTime != null) {
            stmt.setTimestamp(11, tsSchedStartTime, calGMT );
        } else {
            stmt.setNull(11, java.sql.Types.DATE);

How to get Month Name from Calendar?

DateFormat date =  new SimpleDateFormat("dd/MMM/yyyy");
Date date1 = new Date();

How to convert a date String to a Date or Calendar object?


LocalDate.parse( "2015-01-02" )


Java 8 and later has a new java.time framework that makes these other answers outmoded. This framework is inspired by Joda-Time, defined by JSR 310, and extended by the ThreeTen-Extra project. See the Tutorial.

The old bundled classes, java.util.Date/.Calendar, are notoriously troublesome and confusing. Avoid them.


Like Joda-Time, java.time has a class LocalDate to represent a date-only value without time-of-day and without time zone.

ISO 8601

If your input string is in the standard ISO 8601 format of yyyy-MM-dd, you can ask that class to directly parse the string with no need to specify a formatter.

The ISO 8601 formats are used by default in java.time, for both parsing and generating string representations of date-time values.

LocalDate localDate = LocalDate.parse( "2015-01-02" );


If you have a different format, specify a formatter from the java.time.format package. You can either specify your own formatting pattern or let java.time automatically localize as appropriate to a Locale specifying a human language for translation and cultural norms for deciding issues such as period versus comma.

Formatting pattern

Read the DateTimeFormatter class doc for details on the codes used in the format pattern. They vary a bit from the old outmoded java.text.SimpleDateFormat class patterns.

Note how the second argument to the parse method is a method reference, syntax added to Java 8 and later.

String input = "January 2, 2015";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern ( "MMMM d, yyyy" , Locale.US );
LocalDate localDate = LocalDate.parse ( input , formatter );

Dump to console.

System.out.println ( "localDate: " + localDate );

localDate: 2015-01-02

Localize automatically

Or rather than specify a formatting pattern, let java.time localize for you. Call DateTimeFormatter.ofLocalizedDate, and be sure to specify the desired/expected Locale rather than rely on the JVM’s current default which can change at any moment during runtime(!).

String input = "January 2, 2015";
DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDate ( FormatStyle.LONG );
formatter = formatter.withLocale ( Locale.US );
LocalDate localDate = LocalDate.parse ( input , formatter );

Dump to console.

System.out.println ( "input: " + input + " | localDate: " + localDate );

input: January 2, 2015 | localDate: 2015-01-02

How to change date format (MM/DD/YY) to (YYYY-MM-DD) in date picker

This work for me:

          singleDatePicker: true,
          locale: {
           format: 'DD/MM/YYYY'
         calender_style: "picker_4", }, 
function(start, end, label) {
          console.log(start.toISOString(), end.toISOString(), label); 

How to sanity check a date in Java

Assuming that both of those are Strings (otherwise they'd already be valid Dates), here's one way:

package cruft;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DateValidator
    private static final DateFormat DEFAULT_FORMATTER;

        DEFAULT_FORMATTER = new SimpleDateFormat("dd-MM-yyyy");

    public static void main(String[] args)
        for (String dateString : args)
                System.out.println("arg: " + dateString + " date: " + convertDateString(dateString));
            catch (ParseException e)
                System.out.println("could not parse " + dateString);

    public static Date convertDateString(String dateString) throws ParseException
        return DEFAULT_FORMATTER.parse(dateString);

Here's the output I get:

java cruft.DateValidator 32-11-2010 31-02-2010 04-01-2011
could not parse 32-11-2010
could not parse 31-02-2010
arg: 04-01-2011 date: Tue Jan 04 00:00:00 EST 2011

Process finished with exit code 0

As you can see, it does handle both of your cases nicely.

How do I calculate someone's age in Java?

Try to copy this one in your code, then use the method to get the age.

public static int getAge(Date birthday)
    GregorianCalendar today = new GregorianCalendar();
    GregorianCalendar bday = new GregorianCalendar();
    GregorianCalendar bdayThisYear = new GregorianCalendar();

    bdayThisYear.set(Calendar.YEAR, today.get(Calendar.YEAR));

    int age = today.get(Calendar.YEAR) - bday.get(Calendar.YEAR);

    if(today.getTimeInMillis() < bdayThisYear.getTimeInMillis())

    return age;

Specify the date format in XMLGregorianCalendar

Yeah Got it...

Date dob=null;
DateFormat df=new SimpleDateFormat("dd/MM/yyyy");
dob=df.parse( "13/06/1983" );
GregorianCalendar cal = new GregorianCalendar();
XMLGregorianCalendar xmlDate = DatatypeFactory.newInstance().newXMLGregorianCalendarDate(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH)+1, cal.get(Calendar.DAY_OF_MONTH), DatatypeConstants.FIELD_UNDEFINED);

This will give it in correct format.

Calculate business days

Here's a function from the user comments on the date() function page in the PHP manual. It's an improvement of an earlier function in the comments that adds support for leap years.

Enter the starting and ending dates, along with an array of any holidays that might be in between, and it returns the working days as an integer:

//The function returns the no. of business days between two dates and it skips the holidays
function getWorkingDays($startDate,$endDate,$holidays){
    // do strtotime calculations just once
    $endDate = strtotime($endDate);
    $startDate = strtotime($startDate);

    //The total number of days between the two dates. We compute the no. of seconds and divide it to 60*60*24
    //We add one to inlude both dates in the interval.
    $days = ($endDate - $startDate) / 86400 + 1;

    $no_full_weeks = floor($days / 7);
    $no_remaining_days = fmod($days, 7);

    //It will return 1 if it's Monday,.. ,7 for Sunday
    $the_first_day_of_week = date("N", $startDate);
    $the_last_day_of_week = date("N", $endDate);

    //---->The two can be equal in leap years when february has 29 days, the equal sign is added here
    //In the first case the whole interval is within a week, in the second case the interval falls in two weeks.
    if ($the_first_day_of_week <= $the_last_day_of_week) {
        if ($the_first_day_of_week <= 6 && 6 <= $the_last_day_of_week) $no_remaining_days--;
        if ($the_first_day_of_week <= 7 && 7 <= $the_last_day_of_week) $no_remaining_days--;
    else {
        // (edit by Tokes to fix an edge case where the start day was a Sunday
        // and the end day was NOT a Saturday)

        // the day of the week for start is later than the day of the week for end
        if ($the_first_day_of_week == 7) {
            // if the start date is a Sunday, then we definitely subtract 1 day

            if ($the_last_day_of_week == 6) {
                // if the end date is a Saturday, then we subtract another day
        else {
            // the start date was a Saturday (or earlier), and the end date was (Mon..Fri)
            // so we skip an entire weekend and subtract 2 days
            $no_remaining_days -= 2;

    //The no. of business days is: (number of weeks between the two dates) * (5 working days) + the remainder
//---->february in none leap years gave a remainder of 0 but still calculated weekends between first and last day, this is one way to fix it
   $workingDays = $no_full_weeks * 5;
    if ($no_remaining_days > 0 )
      $workingDays += $no_remaining_days;

    //We subtract the holidays
    foreach($holidays as $holiday){
        //If the holiday doesn't fall in weekend
        if ($startDate <= $time_stamp && $time_stamp <= $endDate && date("N",$time_stamp) != 6 && date("N",$time_stamp) != 7)

    return $workingDays;



echo getWorkingDays("2008-12-22","2009-01-02",$holidays)
// => will return 7

How can I use PHP to dynamically publish an ical file to be read by Google Calendar?

Make sure you format the string like this or it wont work

 $content = "BEGIN:VCALENDAR\n".
            "PRODID:-//hacksw/handcal//NONSGML v1.0//EN\n".

How to set time to 24 hour format in Calendar

I am using fullcalendar on my project recently, I don't know what exact view effect you want to achieve, in my project I want to change the event time view from 12h format from

enter image description here

to 24h format.

enter image description here

If this is the effect you want to achieve, the solution below might help:

set timeFormat: 'H:mm'

Month name as a string

I would recommend to use Calendar object and Locale since month names are different for different languages:

// index can be 0 - 11
private String getMonthName(final int index, final Locale locale, final boolean shortName)
    String format = "%tB";

    if (shortName)
        format = "%tb";

    Calendar calendar = Calendar.getInstance(locale);
    calendar.set(Calendar.MONTH, index);
    calendar.set(Calendar.DAY_OF_MONTH, 1);

    return String.format(locale, format, calendar);

Example for full month name:

System.out.println(getMonthName(0, Locale.US, false));

Result: January

Example for short month name:

System.out.println(getMonthName(0, Locale.US, true));

Result: Jan

How to handle calendar TimeZones using Java?

public static Calendar convertToGmt(Calendar cal) {

    Date date = cal.getTime();
    TimeZone tz = cal.getTimeZone();

    log.debug("input calendar has date [" + date + "]");

    //Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT 
    long msFromEpochGmt = date.getTime();

    //gives you the current offset in ms from GMT at the current date
    int offsetFromUTC = tz.getOffset(msFromEpochGmt);
    log.debug("offset is " + offsetFromUTC);

    //create a new calendar in GMT timezone, set to this date and add the offset
    Calendar gmtCal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
    gmtCal.add(Calendar.MILLISECOND, offsetFromUTC);

    log.debug("Created GMT cal with date [" + gmtCal.getTime() + "]");

    return gmtCal;

Here's the output if I pass the current time ("12:09:05 EDT" from Calendar.getInstance()) in:

DEBUG - input calendar has date [Thu Oct 23 12:09:05 EDT 2008]
DEBUG - offset is -14400000
DEBUG - Created GMT cal with date [Thu Oct 23 08:09:05 EDT 2008]

12:09:05 GMT is 8:09:05 EDT.

The confusing part here is that Calendar.getTime() returns you a Date in your current timezone, and also that there is no method to modify the timezone of a calendar and have the underlying date rolled also. Depending on what type of parameter your web service takes, your may just want to have the WS deal in terms of milliseconds from epoch.

How to get last month/year in java?

Use Joda Time Library. It is very easy to handle date, time, calender and locale with it and it will be integrated to java in version 8.

DateTime#minusMonths method would help you get previous month.

DateTime month = new DateTime().minusMonths (1); 

What's the right way to create a date in Java?

You can use SimpleDateFormat

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date d = sdf.parse("21/12/2012");

But I don't know whether it should be considered more right than to use Calendar ...

How do I create a link to add an entry to a calendar?

Here's an Add to Calendar service to serve the purpose for adding an event on

  1. Apple Calendar
  2. Google Calendar
  3. Outlook
  4. Outlook Online
  5. Yahoo! Calendar

The "Add to Calendar" button for events on websites and calendars is easy to install, language independent, time zone and DST compatible. It works perfectly in all modern browsers, tablets and mobile devices, and with Apple Calendar, Google Calendar, Outlook, and Yahoo Calendar.

<div title="Add to Calendar" class="addeventatc">
    Add to Calendar
    <span class="start">03/01/2018 08:00 AM</span>
    <span class="end">03/01/2018 10:00 AM</span>
    <span class="timezone">America/Los_Angeles</span>
    <span class="title">Summary of the event</span>
    <span class="description">Description of the event</span>
    <span class="location">Location of the event</span>

enter image description here

How to set a reminder in Android?

You can use AlarmManager in coop with notification mechanism Something like this:

Intent intent = new Intent(ctx, ReminderBroadcastReceiver.class);
PendingIntent pendingIntent = PendingIntent.getBroadcast(ctx, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
AlarmManager am = (AlarmManager) ctx.getSystemService(Activity.ALARM_SERVICE);
// time of of next reminder. Unix time.
long timeMs =...
if (Build.VERSION.SDK_INT < 19) {
    am.set(AlarmManager.RTC_WAKEUP, timeMs, pendingIntent);
} else {
    am.setExact(AlarmManager.RTC_WAKEUP, timeMs, pendingIntent);

It starts alarm.

public class ReminderBroadcastReceiver extends BroadcastReceiver {
    public void onReceive(Context context, Intent intent) {
        NotificationCompat.Builder builder = new NotificationCompat.Builder(context)
        Intent intentToFire = new Intent(context, Activity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intentToFire, PendingIntent.FLAG_UPDATE_CURRENT);
        NotificationManagerCompat.from(this);.notify((int) System.currentTimeMillis(),;

How to tackle daylight savings using TimeZone in Java

Instead of entering "EST" for the timezone you can enter "EST5EDT" as such. As you noted, just "EDT" does not work. This will account for the daylight savings time issue. The code line looks like this:

Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("EST5EDT"));

Leap year calculation

In shell you can use cal -j YYYY which prints the julian day of the year, If the last julian day is 366, then it is a leap year.

$ function check_leap_year
   if [ `cal -j $year | awk 'NF>0' | awk 'END { print $NF } '` -eq 366 ];
      echo "$year -> Leap Year";
      echo "$year -> Normal Year" ;
$ check_leap_year 1900
1900 -> Normal Year
$ check_leap_year 2000
2000 -> Leap Year
$ check_leap_year 2001
2001 -> Normal Year
$ check_leap_year 2020
2020 -> Leap Year

Using awk, you can do

$ awk -v year=1900 ' BEGIN { jul=strftime("%j",mktime(year " 12 31 0 0 0 ")); print jul } '
$ awk -v year=2000 ' BEGIN { jul=strftime("%j",mktime(year " 12 31 0 0 0 ")); print jul } '
$ awk -v year=2001 ' BEGIN { jul=strftime("%j",mktime(year " 12 31 0 0 0 ")); print jul } '
$ awk -v year=2020 ' BEGIN { jul=strftime("%j",mktime(year " 12 31 0 0 0 ")); print jul } '

Date object to Calendar [Java]


Instant stop = 
                   .plus( Duration.ofMinutes( x ) ) 


Other Answers are correct, especially the Answer by Borgwardt. But those Answers use outmoded legacy classes.

The original date-time classes bundled with Java have been supplanted with java.time classes. Perform your business logic in java.time types. Convert to the old types only where needed to work with old code not yet updated to handle java.time types.

If your Calendar is actually a GregorianCalendar you can convert to a ZonedDateTime. Find new methods added to the old classes to facilitate conversion to/from java.time types.

if( myUtilCalendar instanceof GregorianCalendar ) {
    GregorianCalendar gregCal = (GregorianCalendar) myUtilCalendar; // Downcasting from the interface to the concrete class.
    ZonedDateTime zdt = gregCal.toZonedDateTime();  // Create `ZonedDateTime` with same time zone info found in the `GregorianCalendar`
end if 

If your Calendar is not a Gregorian, call toInstant to get an Instant object. The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds.

Instant instant = myCal.toInstant();

Similarly, if starting with a java.util.Date object, convert to an Instant. The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds (up to nine (9) digits of a decimal fraction).

Instant instant = myUtilDate.toInstant();

Apply a time zone to get a ZonedDateTime.

ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = instant.atZone( z );

To get a java.util.Date object, go through the Instant.

java.util.Date utilDate = java.util.Date.from( zdt.toInstant() );

For more discussion of converting between the legacy date-time types and java.time, and a nifty diagram, see my Answer to another Question.


Represent the span of time as a Duration object. Your input for the duration is a number of minutes as mentioned in the Question.

Duration d = Duration.ofMinutes( yourMinutesGoHere );

You can add that to the start to determine the stop.

Instant stop = d ); 

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to java.time.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

  • Java SE 8 and SE 9 and later
    • Built-in.
    • Part of the standard Java API with a bundled implementation.
    • Java 9 adds some minor features and fixes.
  • Java SE 6 and SE 7
    • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
  • Android

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Java Calendar, getting current month value, clarification needed

Months in Java Calendar are 0-indexed. Calendar.JANUARY isn't a field so you shouldn't be passing it in to the get method.

Find first and last day for previous calendar month in SQL Server Reporting Services (VB.Net)

I'm not familiar with SSRS, but you can get the beginning and end of the previous month in VB.Net using the DateTime constructor, like this:

Dim prevMonth As DateTime = yourDate.AddMonths(-1)

Dim prevMonthStart As New DateTime(prevMonth.Year, prevMonth.Month, 1)
Dim prevMonthEnd As New DateTime(prevMonth.Year, prevMonth.Month, DateTime.DaysInMonth(prevMonth.Year, prevMonth.Month))

(yourDate can be any DateTime object, such as DateTime.Today or #12/23/2003#)

HTML Input Type Date, Open Calendar by default

This is not possible with native HTML input elements. You can use webshim polyfill, which gives you this option by using this markup.

<input type="date" data-date-inline-picker="true" />

Here is a small demo

Java Date vs Calendar

Date should be re-developed. Instead of being a long interger, it should hold year, month, date, hour, minute, second, as separate fields. It might be even good to store the calendar and time zone this date is associated with.

In our natural conversation, if setup an appointment at Nov. 1, 2013 1pm NY Time, this is a DateTime. It is NOT a Calendar. So we should be able to converse like this in Java as well.

When Date is stored as a long integer (of mili seconds since Jan 1 1970 or something), calculating its current date depends on the calendar. Different calendars will give different date. This is from the prospective of giving an absolute time (eg 1 trillion seconds after Big Bang). But often we also need a convenient way of conversation, like an object encapsulating year, month etc.

I wonder if there are new advances in Java to reconcile these 2 objectives. Maybe my java knowledge is too old.

Calendar date to yyyy-MM-dd format in java

java.util.Date object can't represent date in custom format instead you've to use SimpleDateFormat.format method that returns string.

String myString=format1.format(date);

Programmatically add custom event in the iPhone Calendar

Update for swift 4 for Dashrath answer

import UIKit
import EventKit

class ViewController: UIViewController {

    override func viewDidLoad() {

        let eventStore = EKEventStore()

        eventStore.requestAccess( to: EKEntityType.event, completion:{(granted, error) in

            if (granted) && (error == nil) {

                let event = EKEvent(eventStore: eventStore)

                event.title = "My Event"
                event.startDate = Date(timeIntervalSinceNow: TimeInterval())
                event.endDate = Date(timeIntervalSinceNow: TimeInterval())
                event.notes = "Yeah!!!"
                event.calendar = eventStore.defaultCalendarForNewEvents

                var event_id = ""
                    try, span: .thisEvent)
                    event_id = event.eventIdentifier
                catch let error as NSError {
                    print("json error: \(error.localizedDescription)")

                if(event_id != ""){
                    print("event added !")

    override func didReceiveMemoryWarning() {
        // Dispose of any resources that can be recreated.


also don't forget to add permission for calendar usage image for privary setting

Why is January month 0 in Java Calendar?

Because programmers are obsessed with 0-based indexes. OK, it's a bit more complicated than that: it makes more sense when you're working with lower-level logic to use 0-based indexing. But by and large, I'll still stick with my first sentence.

Moment.js get day name from date


var mydate = "2017-06-28T00:00:00";
var weekDayName =  moment(mydate).format('dddd');

mydate is the input date. The variable weekDayName get the name of the day. Here the output is



var mydate = "2017-08-30T00:00:00";_x000D_
console.log('Day in number[0,1,2,3,4,5,6]: '+moment(mydate).format('d'));_x000D_
<script src=""></script>

System.currentTimeMillis() vs. new Date() vs. Calendar.getInstance().getTime()

System.currentTimeMillis() is obviously the most efficient since it does not even create an object, but new Date() is really just a thin wrapper about a long, so it is not far behind. Calendar, on the other hand, is relatively slow and very complex, since it has to deal with the considerably complexity and all the oddities that are inherent to dates and times (leap years, daylight savings, timezones, etc.).

It's generally a good idea to deal only with long timestamps or Date objects within your application, and only use Calendar when you actually need to perform date/time calculations, or to format dates for displaying them to the user. If you have to do a lot of this, using Joda Time is probably a good idea, for the cleaner interface and better performance.

Set Date in a single line

Date date = new DateTime(2014, 6, 20, 0, 0).toDate();

DateTime is from

Number of days in particular month of particular year?

Lets make it as simple if you don't want to hardcode the value of year and month and you want to take the value from current date and time:

Date d = new Date();
String myDate = new SimpleDateFormat("dd/MM/yyyy").format(d);
int iDayFromDate = Integer.parseInt(myDate.substring(0, 2));
int iMonthFromDate = Integer.parseInt(myDate.substring(3, 5));
int iYearfromDate = Integer.parseInt(myDate.substring(6, 10));

YearMonth CurrentYear = YearMonth.of(iYearfromDate, iMonthFromDate);
int lengthOfCurrentMonth = CurrentYear.lengthOfMonth();
System.out.println("Total number of days in current month is " + lengthOfCurrentMonth );

Getting last day of the month in a given string date

With Java 8 DateTime / LocalDateTime :

String dateString = "01/13/2012";
DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("MM/dd/yyyy", Locale.US); 
LocalDate date = LocalDate.parse(dateString, dateFormat);       
ValueRange range = date.range(ChronoField.DAY_OF_MONTH);
Long max = range.getMaximum();
LocalDate newDate = date.withDayOfMonth(max.intValue());


String dateString = "01/13/2012";
DateTimeFormatter dateFormat = DateTimeFormatter.ofPattern("MM/dd/yyyy", Locale.US); 
LocalDate date = LocalDate.parse(dateString, dateFormat);
LocalDate newDate = date.withDayOfMonth(date.getMonth().length(date.isLeapYear()));



LocalDateTime should be used instead of LocalDate if you have time information in your date string . I.E. 2015/07/22 16:49

MySQL DAYOFWEEK() - my week begins with monday

How about subtracting one and changing Sunday


Of course you would have to do this for every query.

How to pass a URI to an intent?

In Intent, you can directly put Uri. You don't need to convert the Uri to string and convert back again to Uri.

Look at this simple approach.

// put uri to intent 

And to get Uri back from intent:

// Get Uri from Intent
Uri imageUri=getIntent().getData();

Getting checkbox values on submit

Just for printing you can use as below :




What are database normal forms and can you give examples?

I've never had a good memory for exact wording, but in my database class I think the professor always said something like:

The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF].

PHP Warning: Unknown: failed to open stream

This isn't a direct answer to the question, but I had the same problem. I installed VSFTPD on my Ubuntu Server VPS. I could upload files, but every file I uploaded didn't have execution permissions (all files had rights "600"). These posts explain explain exactly what you have to do to configure your VSFTPD to set default rights on your files:

How to adjust text font size to fit textview

If a tranformation like allCaps is set, speedplane's approach is buggy. I fixed it, resulting in the following code (sorry, my reputation does not allow me to add this as a comment to speedplane's solution):

import android.content.Context;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;

public class FontFitTextView extends TextView {

    public FontFitTextView(Context context) {

    public FontFitTextView(Context context, AttributeSet attrs) {
        super(context, attrs);

    private void initialise() {
        mTestPaint = new Paint();
        //max size defaults to the initially specified text size unless it is too small

    /* Re size the font so the specified text fits in the text box
     * assuming the text box is the specified width.
    private void refitText(String text, int textWidth) 
        if (getTransformationMethod() != null) {
            text = getTransformationMethod().getTransformation(text, this).toString();

        if (textWidth <= 0)
        int targetWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();
        float hi = 100;
        float lo = 2;
        final float threshold = 0.5f; // How close we have to be


        while((hi - lo) > threshold) {
            float size = (hi+lo)/2;
            if(mTestPaint.measureText(text) >= targetWidth) 
                hi = size; // too big
                lo = size; // too small
        // Use lo so that we undershoot rather than overshoot
        this.setTextSize(TypedValue.COMPLEX_UNIT_PX, lo);

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
        int height = getMeasuredHeight();
        refitText(this.getText().toString(), parentWidth);
        this.setMeasuredDimension(parentWidth, height);

    protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) {
        refitText(text.toString(), this.getWidth());

    protected void onSizeChanged (int w, int h, int oldw, int oldh) {
        if (w != oldw) {
            refitText(this.getText().toString(), w);

    private Paint mTestPaint;

Can't draw Histogram, 'x' must be numeric

Use the dec argument to set "," as the decimal point by adding:

 ce <- read.table("file.txt", header = TRUE, dec = ",")

Create a simple HTTP server with Java?

Java 6 has a default embedded http server.

Check the thread here

By the way, if you plan to have a rest web service, here is a simple example using jersey.

Cannot edit in read-only editor VS Code

I had the Cannot edit in read-only editor error when trying to edit code after stopping the debug mode (for 2-3 minutes after pressing Shift+F5).

Turns out the default Node version (v9.11.1) wasn't exiting gracefully, leaving VScode stuck on read-only.
Simply adding "runtimeVersion": "12.4.0" to my launch.json file fixed it.

alternatively, change your default Node version to the latest stable version (you can see the current version on the DEBUG CONSOLE when starting debug mode).

How do I prevent a form from being resized by the user?

Set the min and max size of form to same numbers. Do not show min and max buttons.

remove empty lines from text file with PowerShell

This will remove empty lines or lines with only whitespace characters (tabs/spaces).

[IO.File]::ReadAllText("FileWithEmptyLines.txt") -replace '\s+\r\n+', "`r`n" | Out-File "c:\FileWithNoEmptyLines.txt"

Get filename from input [type='file'] using jQuery

Try this to Get filename from input [type='file'] using jQuery.

<script type="text/javascript">
            var fileName =[0].name;
            alert('The file "' + fileName +  '" has been selected.');

Taken from @ jQueryPot

Where does npm install packages?

You can find globally installed modules by the command

npm list -g

It will provide you the location where node.js modules have been installed.


If you install node.js modules locally in a folder, you can type the following command to see the location.

npm list

Best way to encode text data for XML

Here is a single line solution using the XElements. I use it in a very small tool. I don't need it a second time so I keep it this way. (Its dirdy doug)

StrVal = (<x a=<%= StrVal %>>END</x>).ToString().Replace("<x a=""", "").Replace(">END</x>", "")

Oh and it only works in VB not in C#

How do I get the full path to a Perl script that is executing?

There are a few ways:

  • $0 is the currently executing script as provided by POSIX, relative to the current working directory if the script is at or below the CWD
  • Additionally, cwd(), getcwd() and abs_path() are provided by the Cwd module and tell you where the script is being run from
  • The module FindBin provides the $Bin & $RealBin variables that usually are the path to the executing script; this module also provides $Script & $RealScript that are the name of the script
  • __FILE__ is the actual file that the Perl interpreter deals with during compilation, including its full path.

I've seen the first three ($0, the Cwd module and the FindBin module) fail under mod_perl spectacularly, producing worthless output such as '.' or an empty string. In such environments, I use __FILE__ and get the path from that using the File::Basename module:

use File::Basename;
my $dirname = dirname(__FILE__);

Fatal error: Can't open and lock privilege tables: Table '' doesn't exist

If you move your datadir, you not only need to give the new datadir permissions, but you need to ensure all parent directories have permission.

I moved my datadir to a hard drive, mounted in Ubuntu as:


and my datadir was Databases.

I had to set permissions to 771 to each of the media, user and Data directories:

sudo chmod 771 *DIR*

If this does not work, another way you can get mysql to work is to change user in /etc/mysql/my.cnf to root; though there are no doubt some issues with doing that from a security perspective.

Cannot connect to repo with TortoiseSVN

Look into this as well:

Issue: After invoking SVN on the command line on a firewalled server, nothing visible happens for 15 seconds, then the program quits with the following error:

svn: E170013: Unable to connect to a repository at URL 'SVN.REPOSITORY.REDACTED'

svn: E730054: Error running context: An existing connection was forcibly closed by the remote host.

Investigation: Internet research on the above errors did not uncover any pertinent information.

Process Tracing (procmon) showed a connection attempt to an Akamai (cloud services) server after the SSL/TLS handshake to the SVN Server. The hostname for the server was not shown in Process tracing. Reverse DNS lookup showed or as the hostname, and the IP was either or (2 entries in DNS cache).

Packet capture tool (MMA) showed a connection attempt to the hostname after the SSL/TLS Handshake to the SVN server.

The windows Crypto API was attempting to connect to Windows Update to retrieve Certificate revocation information (CRL – certificate revocation list). The default timeout for CRL retrieval is 15 seconds. The timeout for authentication on the server is 10 seconds; as 15 is greater than 10, this fails.

Resolution: Internet research uncovered the following: (also see picture at bottom)

Solution 1: Decrease CRL timeout Group Policy -> Computer Config ->Windows Settings -> Security Settings -> Public Key Policies -> Certificate Path Validation Settings -> Network Retrieval – see picture below.

Solution 2: Open firewall for CRL traffic

Solution 3: SVN command line flags (untested) - alternate svn command line flag solution.

Additional Information: Debugging this issue was particularly difficult. SVN 1.8 disabled support for the Neon HTTP RA (repository access) library in favor of the Serf library which removed client debug logging. [1] In addition, the SVN error code returned did not match the string given in svn_error_codes.h [2] Also, SVN Error codes cannot be mapped back to their ENUM label easily, this case SVN error code E170013 maps to SVN_ERR_RA_CANNOT_CREATE_SESSION.


Suggested SVN Changes:

  1. Enable Verbosity on the command like for all operations

  2. Add error ENUM name to stderr

  3. Add config flag for Serf Library debug logging.

Adding two numbers concatenates them instead of calculating the sum

You can also write : var z = x - -y ; And you get correct answer.


<input type="text" id="number1" name="">
<input type="text" id="number2" name="">
<button type="button" onclick="myFunction()">Submit</button>

<p id="demo"></p>

    function myFunction() {
        var x, y ;

        x = document.getElementById('number1').value;
        y = document.getElementById('number2').value;

        var z = x - -y ;

        document.getElementById('demo').innerHTML = z;

TypeError: no implicit conversion of Symbol into Integer

Ive come across this many times in my work, an easy work around that I found is to ask if the array element is a Hash by class.

if i.class == Hash

    notation like i[:label] will work in this block and not throw that error


What's the difference between compiled and interpreted language?

Here is the Basic Difference between Compiler vs Interpreter Language.

Compiler Language

  • Takes entire program as single input and converts it into object code which is stored in the file.
  • Intermediate Object code is generated
  • e.g: C,C++
  • Compiled programs run faster because compilation is done before execution.
  • Memory requirement is more due to the creation of object code.
  • Error are displayed after the entire program is compiled
  • Source code ---Compiler ---Machine Code ---Output

Interpreter Language:

  • Takes single instruction as single input and executes instructions.
  • Intermediate Object code is NOT generated
  • e.g: Perl, Python, Matlab
  • Interpreted programs run slower because compilation and execution take place simultaneously.
  • Memory requirement is less.
  • Error are displayed for every single instruction.
  • Source Code ---Interpreter ---Output

Nested iframes, AKA Iframe Inception

If browser supports iframe, then DOM inside iframe come from src attribute of respective tag. Contents that are inside iframe tag are used as a fall back mechanism where browser does not supports iframe tag.


Java Spring Boot: How to map my app root (“/”) to index.html?

It would have worked out of the box if you hadn't used @EnableWebMvc annotation. When you do that you switch off all the things that Spring Boot does for you in WebMvcAutoConfiguration. You could remove that annotation, or you could add back the view controller that you switched off:

public void addViewControllers(ViewControllerRegistry registry) {

Squash my last X commits together using Git

I think the easiest way to do this is by making a new branch based on master and doing a merge --squash of the feature branch.

git checkout master
git checkout -b feature_branch_squashed
git merge --squash feature_branch

Then you have all of the changes ready to commit.

static and extern global variables in C and C++

When you #include a header, it's exactly as if you put the code into the source file itself. In both cases the varGlobal variable is defined in the source so it will work no matter how it's declared.

Also as pointed out in the comments, C++ variables at file scope are not static in scope even though they will be assigned to static storage. If the variable were a class member for example, it would need to be accessible to other compilation units in the program by default and non-class members are no different.

Difference between two lists

Since the Except extension method operates on two IEumerables, it seems to me that it will be a O(n^2) operation. If performance is an issue (if say your lists are large), I'd suggest creating a HashSet from list1 and use HashSet's ExceptWith method.

What is Inversion of Control?

For example, task#1 is to create object. Without IOC concept, task#1 is supposed to be done by Programmer.But With IOC concept, task#1 would be done by container.

In short Control gets inverted from Programmer to container. So, it is called as inversion of control.

I found one good example here.

Font-awesome, input type 'submit'

use button type="submit" instead of input

<button type="submit" class="btn btn-success">
    <i class="fa fa-arrow-circle-right fa-lg"></i> Next

for Font Awesome 3.2.0 use

<button type="submit" class="btn btn-success">
    <i class="icon-circle-arrow-right icon-large"></i> Next

How can you check for a #hash in a URL using JavaScript?

Put the following:

<script type="text/javascript">
    if (location.href.indexOf("#") != -1) {
        // Your code in here accessing the string like this
        // location.href.substr(location.href.indexOf("#"))

Loop through properties in JavaScript object with Lodash

Lets take below object as example

let obj = { property1: 'value 1', property2: 'value 2'};

First fetch all the key in the obj

let keys = Object.keys(obj) //it will return array of keys

and then loop through it

keys.forEach(key => //your way)

just putting all together

Object.keys(obj).forEach(key=>{/*code here*/})

Using IF ELSE in Oracle

IF is a PL/SQL construct. If you are executing a query, you are using SQL not PL/SQL.

In SQL, you can use a CASE statement in the query itself

                (CASE WHEN b.salesman = 'VIKKIE'
                      THEN 'ICKY'
                      ELSE b.salesman
                NVL(a.manufacturer,'Not Set') Manufacturer
  FROM inv_items a, 
       arv_sales b
 WHERE = '100'
   AND =
   AND A.ITEM_KEY = b.item_key   
   AND a.item LIKE 'BX%'
   AND b.salesman in ('01','15')
   AND trans_date BETWEEN to_date('010113','mmddrr')
                      and to_date('011713','mmddrr')
ORDER BY a.item

Since you aren't doing any aggregation, you don't want a GROUP BY in your query. Are you really sure that you need the DISTINCT? People often throw that in haphazardly or add it when they are missing a join condition rather than considering whether it is really necessary to do the extra work to identify and remove duplicates.

Fit background image to div

You can use this attributes:

background-size: contain;
background-repeat: no-repeat;

and you code is then like this:

 <div style="text-align:center;background-image: url(/media/img_1_bg.jpg); background-size: contain;
background-repeat: no-repeat;" id="mainpage">

Difference between volatile and synchronized in Java

synchronized is method level/block level access restriction modifier. It will make sure that one thread owns the lock for critical section. Only the thread,which own a lock can enter synchronized block. If other threads are trying to access this critical section, they have to wait till current owner releases the lock.

volatile is variable access modifier which forces all threads to get latest value of the variable from main memory. No locking is required to access volatile variables. All threads can access volatile variable value at same time.

A good example to use volatile variable : Date variable.

Assume that you have made Date variable volatile. All the threads, which access this variable always get latest data from main memory so that all threads show real (actual) Date value. You don't need different threads showing different time for same variable. All threads should show right Date value.

enter image description here

Have a look at this article for better understanding of volatile concept.

Lawrence Dol cleary explained your read-write-update query.

Regarding your other queries

When is it more suitable to declare variables volatile than access them through synchronized?

You have to use volatile if you think all threads should get actual value of the variable in real time like the example I have explained for Date variable.

Is it a good idea to use volatile for variables that depend on input?

Answer will be same as in first query.

Refer to this article for better understanding.

How do I delete everything in Redis?

Heads up that FLUSHALL may be overkill. FLUSHDB is the one to flush a database only. FLUSHALL will wipe out the entire server. As in every database on the server. Since the question was about flushing a database I think this is an important enough distinction to merit a separate answer.

Error in installation a R package

In my case, I had to close R session and reinstall all packages. In that session I worked with large tables, I suspect this might have had the effect.

jQuery Ajax PUT with parameters

You can use the PUT method and pass data that will be included in the body of the request:

let data = {"key":"value"}

    type: 'PUT',
    url: '',
    contentType: 'application/json',
    data: JSON.stringify(data), // access in body
}).done(function () {
}).fail(function (msg) {
}).always(function (msg) {

How to solve “Microsoft Visual Studio (VS)” error “Unable to connect to the configured development Web server”

We solved this problem with deleting .vs folder on project folder and deleting temporary ASP.NET files.

1. Close the Visual Studio.
2. Delete .vs folder on project folder that includes applicationhost.config file.
3. Delete temporary ASP.NET Files located: C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files\root

Having services in React application

I am from Angular as well and trying out React, as of now, one recommended(?) way seems to be using High-Order Components:

A higher-order component (HOC) is an advanced technique in React for reusing component logic. HOCs are not part of the React API, per se. They are a pattern that emerges from React’s compositional nature.

Let's say you have input and textarea and like to apply the same validation logic:

const Input = (props) => (
  <input type="text"
    onChange={props.onChange} />
const TextArea = (props) => (
  <textarea rows="3"
    onChange={props.onChange} >

Then write a HOC that does validate and style wrapped component:

function withValidator(WrappedComponent) {
  return class extends React.Component {
    constructor(props) {

      this.validateAndStyle = this.validateAndStyle.bind(this)
      this.state = {
        style: {}

    validateAndStyle(e) {
      const value =
      const valid = value && value.length > 3 // shared logic here
      const style = valid ? {} : { border: '2px solid red' }
      console.log(value, valid)
        style: style

    render() {
      return <WrappedComponent
        {...this.props} />

Now those HOCs share the same validating behavior:

const InputWithValidator = withValidator(Input)
const TextAreaWithValidator = withValidator(TextArea)

    <InputWithValidator />
    <TextAreaWithValidator />
), document.getElementById('root'));

I created a simple demo.

Edit: Another demo is using props to pass an array of functions so that you can share logic composed by multiple validating functions across HOCs like:

<InputWithValidator validators={[validator1,validator2]} />
<TextAreaWithValidator validators={[validator1,validator2]} />

Edit2: React 16.8+ provides a new feature, Hook, another nice way to share logic.

const Input = (props) => {
  const inputValidation = useInputValidation()

  return (
    <input type="text"
    {...inputValidation} />

function useInputValidation() {
  const [value, setValue] = useState('')
  const [style, setStyle] = useState({})

  function handleChange(e) {
    const value =
    const valid = value && value.length > 3 // shared logic here
    const style = valid ? {} : { border: '2px solid red' }
    console.log(value, valid)

  return {
    onChange: handleChange

JavaScript backslash (\) in variables is causing an error

The backslash (\) is an escape character in Javascript (along with a lot of other C-like languages). This means that when Javascript encounters a backslash, it tries to escape the following character. For instance, \n is a newline character (rather than a backslash followed by the letter n).

In order to output a literal backslash, you need to escape it. That means \\ will output a single backslash (and \\\\ will output two, and so on). The reason "aa ///\" doesn't work is because the backslash escapes the " (which will print a literal quote), and thus your string is not properly terminated. Similarly, "aa ///\\\" won't work, because the last backslash again escapes the quote.

Just remember, for each backslash you want to output, you need to give Javascript two.

String Concatenation in EL

This answer is obsolete. Technology has moved on. Unless you're working with legacy systems see Joel's answer.

There is no string concatenation operator in EL. If you don't need the concatenated string to pass into some other operation, just put these expressions next to each other:

${value}${(empty value)? 'none' : ' enabled'}

Bootstrap trying to load map file. How to disable it? Do I need to do it?

Deleting this line fixes it, but the problem is the boostrap files are in bower_components and not checked into source control.

So, every developer on the team will get the css file with the map reference when they pull the repo and do bower install (which is part of using a new repo).

The file should not have the reference to a map that is not there.

Creating a search form in PHP to search a database?

try this out let me know what happens.


<form action="form.php" method="post"> 
Search: <input type="text" name="term" /><br /> 
<input type="submit" value="Submit" /> 


$term = mysql_real_escape_string($_REQUEST['term']);    

$sql = "SELECT * FROM liam WHERE Description LIKE '%".$term."%'";
$r_query = mysql_query($sql);

while ($row = mysql_fetch_array($r_query)){ 
echo 'Primary key: ' .$row['PRIMARYKEY']; 
echo '<br /> Code: ' .$row['Code']; 
echo '<br /> Description: '.$row['Description']; 
echo '<br /> Category: '.$row['Category']; 
echo '<br /> Cut Size: '.$row['CutSize'];  

Edit: Cleaned it up a little more.

Final Cut (my test file):

$db_hostname = 'localhost';
$db_username = 'demo';
$db_password = 'demo';
$db_database = 'demo';

// Database Connection String
$con = mysql_connect($db_hostname,$db_username,$db_password);
if (!$con)
  die('Could not connect: ' . mysql_error());

mysql_select_db($db_database, $con);

<!DOCTYPE html>
<html lang="en">
        <meta charset="utf-8" />
<form action="" method="post">  
Search: <input type="text" name="term" /><br />  
<input type="submit" value="Submit" />  
if (!empty($_REQUEST['term'])) {

$term = mysql_real_escape_string($_REQUEST['term']);     

$sql = "SELECT * FROM liam WHERE Description LIKE '%".$term."%'"; 
$r_query = mysql_query($sql); 

while ($row = mysql_fetch_array($r_query)){  
echo 'Primary key: ' .$row['PRIMARYKEY'];  
echo '<br /> Code: ' .$row['Code'];  
echo '<br /> Description: '.$row['Description'];  
echo '<br /> Category: '.$row['Category'];  
echo '<br /> Cut Size: '.$row['CutSize'];   


How do I get the raw request body from the Request.Content object using .net 4 api endpoint

You can get the raw data by calling ReadAsStringAsAsync on the Request.Content property.

string result = await Request.Content.ReadAsStringAsync();

There are various overloads if you want it in a byte or in a stream. Since these are async-methods you need to make sure your controller is async:

public async Task<IHttpActionResult> GetSomething()
    var rawMessage = await Request.Content.ReadAsStringAsync();
    // ...
    return Ok();

EDIT: if you're receiving an empty string from this method, it means something else has already read it. When it does that, it leaves the pointer at the end. An alternative method of doing this is as follows:

public IHttpActionResult GetSomething()
    var reader = new StreamReader(Request.Body);
    reader.BaseStream.Seek(0, SeekOrigin.Begin); 
    var rawMessage = reader.ReadToEnd();

    return Ok();

In this case, your endpoint doesn't need to be async (unless you have other async-methods)

Select columns based on string match - dplyr::select

No need to use select just use [ instead

data[,grepl("search_string", colnames(data))]

Let's try with iris dataset

>iris[,grepl("Sepal", colnames(iris))]
  Sepal.Length Sepal.Width
1          5.1         3.5
2          4.9         3.0
3          4.7         3.2
4          4.6         3.1
5          5.0         3.6
6          5.4         3.9

Http Get using Android HttpURLConnection

Here is a complete AsyncTask class

public class GetMethodDemo extends AsyncTask<String , Void ,String> {
    String server_response;

    protected String doInBackground(String... strings) {

        URL url;
        HttpURLConnection urlConnection = null;

        try {
            url = new URL(strings[0]);
            urlConnection = (HttpURLConnection) url.openConnection();

            int responseCode = urlConnection.getResponseCode();

            if(responseCode == HttpURLConnection.HTTP_OK){
                server_response = readStream(urlConnection.getInputStream());
                Log.v("CatalogClient", server_response);

        } catch (MalformedURLException e) {
        } catch (IOException e) {

        return null;

    protected void onPostExecute(String s) {

        Log.e("Response", "" + server_response);


// Converting InputStream to String

private String readStream(InputStream in) {
        BufferedReader reader = null;
        StringBuffer response = new StringBuffer();
        try {
            reader = new BufferedReader(new InputStreamReader(in));
            String line = "";
            while ((line = reader.readLine()) != null) {
        } catch (IOException e) {
        } finally {
            if (reader != null) {
                try {
                } catch (IOException e) {
        return response.toString();

To Call this AsyncTask class

new GetMethodDemo().execute("your web-service url");

How to find/identify large commits in git history?

I was unable to make use of the most popular answer because the --batch-check command-line switch to Git 1.8.3 (that I have to use) does not accept any arguments. The ensuing steps have been tried on CentOS 6.5 with Bash 4.1.2

Key Concepts

In Git, the term blob implies the contents of a file. Note that a commit might change the contents of a file or pathname. Thus, the same file could refer to a different blob depending on the commit. A certain file could be the biggest in the directory hierarchy in one commit, while not in another. Therefore, the question of finding large commits instead of large files, puts matters in the correct perspective.

For The Impatient

Command to print the list of blobs in descending order of size is:

git cat-file --batch-check < <(git rev-list --all --objects  | \
awk '{print $1}')  | grep blob  | sort -n -r -k 3

Sample output:

3a51a45e12d4aedcad53d3a0d4cf42079c62958e blob 305971200
7c357f2c2a7b33f939f9b7125b155adbd7890be2 blob 289163620

To remove such blobs, use the BFG Repo Cleaner, as mentioned in other answers. Given a file blobs.txt that just contains the blob hashes, for example:



java -jar bfg.jar -bi blobs.txt <repo_dir>

The question is about finding the commits, which is more work than finding blobs. To know, please read on.

Further Work

Given a commit hash, a command that prints hashes of all objects associated with it, including blobs, is:

git ls-tree -r --full-tree <commit_hash>

So, if we have such outputs available for all commits in the repo, then given a blob hash, the bunch of commits are the ones that match any of the outputs. This idea is encoded in the following script:


find_commit() {
    cd ${DB_DIR}
    for f in *; do
        if grep -q $1 ${f}; then
            echo ${f}
    cd - > /dev/null

create_db() {
    local tfile='/tmp/commits.txt'
    mkdir -p ${DB_DIR} && cd ${DB_DIR}
    git rev-list --all > ${tfile}

    while read commit_hash; do
        if [[ ! -e ${commit_hash} ]]; then
            git ls-tree -r --full-tree ${commit_hash} > ${commit_hash}
    done < ${tfile}
    cd - > /dev/null
    rm -f ${tfile}


while read id; do
    find_commit ${id};

If the contents are saved in a file named then a typical invocation will be as under:

cat blobs.txt |

As earlier, the file blobs.txt lists blob hashes, one per line. The create_db() function saves a cache of all commit listings in a sub-directory in the current directory.

Some stats from my experiments on a system with two Intel(R) Xeon(R) CPU E5-2620 2.00GHz processors presented by the OS as 24 virtual cores:

  • Total number of commits in the repo = almost 11,000
  • File creation speed = 126 files/s. The script creates a single file per commit. This occurs only when the cache is being created for the first time.
  • Cache creation overhead = 87 s.
  • Average search speed = 522 commits/s. The cache optimization resulted in 80% reduction in running time.

Note that the script is single threaded. Therefore, only one core would be used at any one time.

What does it mean to "program to an interface"?

It makes your code a lot more extensible and easier to maintain when you have sets of similar classes. I am a junior programmer, so I am no expert, but I just finished a project that required something similar.

I work on client side software that talks to a server running a medical device. We are developing a new version of this device that has some new components that the customer must configure at times. There are two types of new components, and they are different, but they are also very similar. Basically, I had to create two config forms, two lists classes, two of everything.

I decided that it would be best to create an abstract base class for each control type that would hold almost all of the real logic, and then derived types to take care of the differences between the two components. However, the base classes would not have been able to perform operations on these components if I had to worry about types all of the time (well, they could have, but there would have been an "if" statement or switch in every method).

I defined a simple interface for these components and all of the base classes talk to this interface. Now when I change something, it pretty much 'just works' everywhere and I have no code duplication.

Iterating over a 2 dimensional python list

same way you did the fill in, but reverse the indexes:

>>> for j in range(columns):
...     for i in range(rows):
...        print mylist[i][j],
0,0 1,0 2,0 0,1 1,1 2,1

Display more Text in fullcalendar

as a possible solution: Add some extra more content to the title. Overwrite this css style:

 .fc-day-grid-event .fc-content {
   white-space: normal; 

$(document).ready equivalent without jQuery

Most vanilla JS Ready functions do NOT consider the scenario where the DOMContentLoaded handler is set after the document is already loaded - Which means the function will never run. This can happen if you look for DOMContentLoaded within an async external script (<script async src="file.js"></script>).

The code below checks for DOMContentLoaded only if the document's readyState isn't already interactive or complete.

var DOMReady = function(callback) {
  document.readyState === "interactive" || document.readyState === "complete" ? callback() : document.addEventListener("DOMContentLoaded", callback());
DOMReady(function() {
  //DOM ready!

If you want to support IE aswell:

var DOMReady = function(callback) {
    if (document.readyState === "interactive" || document.readyState === "complete") {
    } else if (document.addEventListener) {
        document.addEventListener('DOMContentLoaded', callback());
    } else if (document.attachEvent) {
        document.attachEvent('onreadystatechange', function() {
            if (document.readyState != 'loading') {

DOMReady(function() {
  // DOM ready!

Returning data from Axios API

you can populate the data you want with a simple callback function, let's say we have a list named lst that we want to populate, we have a function that pupulates pupulates list,

const lst = [];  
const populateData = (data) => {lst.push(data)} 

now we can pass the callback function to the function which is making the axios call and we can pupulate the list when we get data from response.

now we make our function that makes the request and pass populateData as a callback function.

function axiosTest (populateData) {

How can I get the current PowerShell executing file?

If you only want the filename (not the full path) use this:

$ScriptName = $MyInvocation.MyCommand.Name

How to declare a Fixed length Array in TypeScript

The Tuple approach :

This solution provides a strict FixedLengthArray (ak.a. SealedArray) type signature based in Tuples.

Syntax example :

// Array containing 3 strings
let foo : FixedLengthArray<[string, string, string]> 

This is the safest approach, considering it prevents accessing indexes out of the boundaries.

Implementation :

type ArrayLengthMutationKeys = 'splice' | 'push' | 'pop' | 'shift' | 'unshift' | number
type ArrayItems<T extends Array<any>> = T extends Array<infer TItems> ? TItems : never
type FixedLengthArray<T extends any[]> =
  Pick<T, Exclude<keyof T, ArrayLengthMutationKeys>>
  & { [Symbol.iterator]: () => IterableIterator< ArrayItems<T> > }

Tests :

var myFixedLengthArray: FixedLengthArray< [string, string, string]>

// Array declaration tests
myFixedLengthArray = [ 'a', 'b', 'c' ]  // ? OK
myFixedLengthArray = [ 'a', 'b', 123 ]  // ? TYPE ERROR
myFixedLengthArray = [ 'a' ]            // ? LENGTH ERROR
myFixedLengthArray = [ 'a', 'b' ]       // ? LENGTH ERROR

// Index assignment tests 
myFixedLengthArray[1] = 'foo'           // ? OK
myFixedLengthArray[1000] = 'foo'        // ? INVALID INDEX ERROR

// Methods that mutate array length
myFixedLengthArray.push('foo')          // ? MISSING METHOD ERROR
myFixedLengthArray.pop()                // ? MISSING METHOD ERROR

// Direct length manipulation
myFixedLengthArray.length = 123         // ? READ-ONLY ERROR

// Destructuring
var [ a ] = myFixedLengthArray          // ? OK
var [ a, b ] = myFixedLengthArray       // ? OK
var [ a, b, c ] = myFixedLengthArray    // ? OK
var [ a, b, c, d ] = myFixedLengthArray // ? INVALID INDEX ERROR

(*) This solution requires the noImplicitAny typescript configuration directive to be enabled in order to work (commonly recommended practice)

The Array(ish) approach :

This solution behaves as an augmentation of the Array type, accepting an additional second parameter(Array length). Is not as strict and safe as the Tuple based solution.

Syntax example :

let foo: FixedLengthArray<string, 3> 

Keep in mind that this approach will not prevent you from accessing an index out of the declared boundaries and set a value on it.

Implementation :

type ArrayLengthMutationKeys = 'splice' | 'push' | 'pop' | 'shift' |  'unshift'
type FixedLengthArray<T, L extends number, TObj = [T, ...Array<T>]> =
  Pick<TObj, Exclude<keyof TObj, ArrayLengthMutationKeys>>
  & {
    readonly length: L 
    [ I : number ] : T
    [Symbol.iterator]: () => IterableIterator<T>   

Tests :

var myFixedLengthArray: FixedLengthArray<string,3>

// Array declaration tests
myFixedLengthArray = [ 'a', 'b', 'c' ]  // ? OK
myFixedLengthArray = [ 'a', 'b', 123 ]  // ? TYPE ERROR
myFixedLengthArray = [ 'a' ]            // ? LENGTH ERROR
myFixedLengthArray = [ 'a', 'b' ]       // ? LENGTH ERROR

// Index assignment tests 
myFixedLengthArray[1] = 'foo'           // ? OK
myFixedLengthArray[1000] = 'foo'        // ? SHOULD FAIL

// Methods that mutate array length
myFixedLengthArray.push('foo')          // ? MISSING METHOD ERROR
myFixedLengthArray.pop()                // ? MISSING METHOD ERROR

// Direct length manipulation
myFixedLengthArray.length = 123         // ? READ-ONLY ERROR

// Destructuring
var [ a ] = myFixedLengthArray          // ? OK
var [ a, b ] = myFixedLengthArray       // ? OK
var [ a, b, c ] = myFixedLengthArray    // ? OK
var [ a, b, c, d ] = myFixedLengthArray // ? SHOULD FAIL

Remove object from a list of objects in python

del array[0]

where 0 is the index of the object in the list (there is no array in python)

Why can I ping a server but not connect via SSH?

On the server, try:

netstat -an 

and look to see if tcp port 22 is opened (use findstr in Windows or grep in Unix).

Bash: infinite sleep (infinite blocking)

This approach will not consume any resources for keeping process alive.

while :; do sleep 1; done & kill -STOP $! && wait $!


  • while :; do sleep 1; done & Creates a dummy process in background
  • kill -STOP $! Stops the background process
  • wait $! Wait for the background process, this will be blocking forever, cause background process was stopped before

pyplot scatter plot marker size

This can be a somewhat confusing way of defining the size but you are basically specifying the area of the marker. This means, to double the width (or height) of the marker you need to increase s by a factor of 4. [because A = WH => (2W)(2H)=4A]

There is a reason, however, that the size of markers is defined in this way. Because of the scaling of area as the square of width, doubling the width actually appears to increase the size by more than a factor 2 (in fact it increases it by a factor of 4). To see this consider the following two examples and the output they produce.

# doubling the width of markers
x = [0,2,4,6,8,10]
y = [0]*len(x)
s = [20*4**n for n in range(len(x))]


enter image description here

Notice how the size increases very quickly. If instead we have

# doubling the area of markers
x = [0,2,4,6,8,10]
y = [0]*len(x)
s = [20*2**n for n in range(len(x))]


enter image description here

Now the apparent size of the markers increases roughly linearly in an intuitive fashion.

As for the exact meaning of what a 'point' is, it is fairly arbitrary for plotting purposes, you can just scale all of your sizes by a constant until they look reasonable.

Hope this helps!

Edit: (In response to comment from @Emma)

It's probably confusing wording on my part. The question asked about doubling the width of a circle so in the first picture for each circle (as we move from left to right) it's width is double the previous one so for the area this is an exponential with base 4. Similarly the second example each circle has area double the last one which gives an exponential with base 2.

However it is the second example (where we are scaling area) that doubling area appears to make the circle twice as big to the eye. Thus if we want a circle to appear a factor of n bigger we would increase the area by a factor n not the radius so the apparent size scales linearly with the area.

Edit to visualize the comment by @TomaszGandor:

This is what it looks like for different functions of the marker size:

Exponential, Square, or Linear size

x = [0,2,4,6,8,10,12,14,16,18]
s_exp = [20*2**n for n in range(len(x))]
s_square = [20*n**2 for n in range(len(x))]
s_linear = [20*n for n in range(len(x))]
plt.scatter(x,[1]*len(x),s=s_exp, label='$s=2^n$', lw=1)
plt.scatter(x,[0]*len(x),s=s_square, label='$s=n^2$')
plt.scatter(x,[-1]*len(x),s=s_linear, label='$s=n$')
plt.legend(loc='center left', bbox_to_anchor=(1.1, 0.5), labelspacing=3)

How can I show an image using the ImageView component in javafx and fxml?

ImageView image;

public void initialize(URL url, ResourceBundle rb) {
  image.setImage(new Image ("/about.jpg"));

What is the email subject length limit?

I don't believe that there is a formal limit here, and I'm pretty sure there isn't any hard limit specified in the RFC either, as you found.

I think that some pretty common limitations for subject lines in general (not just e-mail) are:

  • 80 Characters
  • 128 Characters
  • 256 Characters

Obviously, you want to come up with something that is reasonable. If you're writing an e-mail client, you may want to go with something like 256 characters, and obviously test thoroughly against big commercial servers out there to make sure they serve your mail correctly.

Hope this helps!

Can't Load URL: The domain of this URL isn't included in the app's domains

I had the same problem, and it came from a wrong client_id / Facebook App ID.

Did you switch your Facebook app to "public" or "online ? When you do so, Facebook creates a new app with a new App ID.

You can compare the "client_id" parameter value in the url with the one in your Facebook dashboard.

Also Make sure your app is public. Click on + Add product Now go to products => Facebook Login Now do the following:

Valid OAuth redirect URIs :

How to programmatically click a button in WPF?

WPF takes a slightly different approach than WinForms here. Instead of having the automation of a object built into the API, they have a separate class for each object that is responsible for automating it. In this case you need the ButtonAutomationPeer to accomplish this task.

ButtonAutomationPeer peer = new ButtonAutomationPeer(someButton);
IInvokeProvider invokeProv = peer.GetPattern(PatternInterface.Invoke) as IInvokeProvider;

Here is a blog post on the subject.

Note: IInvokeProvider interface is defined in the UIAutomationProvider assembly.

Which Android phones out there do have a gyroscope?

Since I have recently developed an Android application using gyroscope data (steady compass), I tried to collect a list with such devices. This is not an exhaustive list at all, but it is what I have so far:

*** Phones:

  • HTC Sensation
  • HTC Sensation XL
  • HTC Evo 3D
  • HTC One S
  • HTC One X
  • Huawei Ascend P1
  • Huawei Ascend X (U9000)
  • Huawei Honor (U8860)
  • LG Nitro HD (P930)
  • LG Optimus 2x (P990)
  • LG Optimus Black (P970)
  • LG Optimus 3D (P920)
  • Samsung Galaxy S II (i9100)
  • Samsung Galaxy S III (i9300)
  • Samsung Galaxy R (i9103)
  • Samsung Google Nexus S (i9020)
  • Samsung Galaxy Nexus (i9250)
  • Samsung Galaxy J3 (2017) model
  • Samsung Galaxy Note (n7000)
  • Sony Xperia P (LT22i)
  • Sony Xperia S (LT26i)

*** Tablets:

  • Acer Iconia Tab A100 (7")
  • Acer Iconia Tab A500 (10.1")
  • Asus Eee Pad Transformer (TF101)
  • Asus Eee Pad Transformer Prime (TF201)
  • Motorola Xoom (mz604)
  • Samsung Galaxy Tab (p1000)
  • Samsung Galaxy Tab 7 plus (p6200)
  • Samsung Galaxy Tab 10.1 (p7100)
  • Sony Tablet P
  • Sony Tablet S
  • Toshiba Thrive 7"
  • Toshiba Trhive 10"

Hope the list keeps growing and hope that gyros will be soon available on mid and low price smartphones.

How To Set Text In An EditText

If you want to set text at design time in xml file just simple android:text="username" add this property.


If you want to set text programmatically in Java

EditText edtUsername = findViewById(;

and in kotlin same like java using getter/setter


But if you want to use .text from principle then

edtUsername.text = Editable.Factory.getInstance().newEditable("username")

because of EditText.text requires an editable at firstplace not String

Chain-calling parent initialisers in python

Python 3 includes an improved super() which allows use like this:


How to access the first property of a Javascript object?

Solution with lodash library:

_.find(example) // => {name: "foo1"}

but there is no guarantee of the object properties internal storage order because it depends on javascript VM implementation.

How can I solve "Non-static method xxx:xxx() should not be called statically in PHP 5.4?

I solved this with one code line, as follow: In file index.php, at your template root, after this code line:

defined( '_JEXEC' ) or die( 'Restricted access' );

paste this line: ini_set ('display_errors', 'Off');

Don't worry, be happy...

posted by Jenio.

ImportError: No module named - Python

Make sure if root project directory is coming up in sys.path output. If not, please add path of root project directory to sys.path.

Hide Show content-list with only CSS, no javascript used

There is 3 rapid examples with pure CSS and without javascript where the content appears "on click", with a "maintained click" and a third "onhover" (all only tested in Chrome). Sorry for the up of this post but this question are the first seo result and maybe my contribution can help beginner like me

I think (not tested) but the advantage of argument "content" that you can add great icon like from Font Awesome (its \f-Code) or an hexadecimal icon in place of the text "Hide" and "Show" to internationalize the trick.

example link

label { position: absolute; top:0; left:0}

input#show, input#hide {

span#content {
    display: block;
    -webkit-transition: opacity 1s ease-out;
    transition: opacity 1s ease-out;
    opacity: 0; 
    height: 0;
    font-size: 0;
    overflow: hidden;

input#show:checked ~ .show:before {
    content: ""
input#show:checked ~ .hide:before {
    content: "Hide"

input#hide:checked ~ .hide:before {
    content: ""
input#hide:checked ~ .show:before {
    content: "Show"
input#show:checked ~ span#content {
    opacity: 1;
    font-size: 100%;
    height: auto;
input#hide:checked ~ span#content {
    display: block;
    -webkit-transition: opacity 1s ease-out;
    transition: opacity 1s ease-out;
    opacity: 0; 
    height: 0;
    font-size: 0;
    overflow: hidden;
<input type="radio" id="show" name="group">   
<input type="radio" id="hide" name="group" checked>
<label for="hide" class="hide"></label>
<label for="show" class="show"></label>
<span id="content">Lorem iupsum dolor si amet</span>

#show1 { position: absolute; top:20px; left:0}
#content1 {
    display: block;
    -webkit-transition: opacity 1s ease-out;
    transition: opacity 1s ease-out;
    opacity: 0; 
    height: 0;
    font-size: 0;
    overflow: hidden;
#show1:before {
    content: "Show"
#show1:active.show1:before {
    content: "Hide"
#show1:active ~ span#content1 {
    opacity: 1;
    font-size: 100%;
    height: auto;

<div id="show1" class="show1"></div>
<span id="content1">Ipsum Lorem</span>

#show2 { position: absolute; top:40px; left:0}
#content2 {
    display: block;
    -webkit-transition: opacity 1s ease-out;
    transition: opacity 1s ease-out;
    opacity: 0; 
    height: 0;
    font-size: 0;
    overflow: hidden;
#show2:before {
    content: "Show"
#show2:hover.show2:before {
    content: "Hide"
#show2:hover ~ span#content2 {
    opacity: 1;
    font-size: 100%;
    height: auto;

/* extra */
#content, #content1, #content2 {
    float: left;
    margin: 100px auto;

<div id="show2" class="show2"></div>
<span id="content2">Lorem Ipsum</span>

How to Change Font Size in drawString Java

code example below:

g.setFont(new Font("TimesRoman", Font.PLAIN, 30));
g.drawString("Welcome to the Java Applet", 20 , 20);

How do I add a library path in cmake?

might fail working with link_directories, then add each static library like following:

target_link_libraries(foo /path_to_static_library/libbar.a)

Clean out Eclipse workspace metadata

In my case eclipse is not showing parent class function on $this, so I perform below mention points and it starts works:-

I go to my /var/www/ folder and check for .metadata folder (Here check the .log file and it shows) Resource is out of sync with the file system: 1. Go to Eclipse --> Project --> Clean 2. Windows -- preferences --> General --> Workspace --> And set it to "Refresh Automatically"

After that boom - things gets start working :)

If you want to load variables from other files too then ado this :- Eclipse-->Windows-->Preferences-->Php-->Editor-->Content Assist --> and check "show variable from other files"

Then it will show element , variables and other functions also.

GitHub center image

My way to resolve the problem with image positioning was to use the HTML attributes:

![Image](Image.svg){ width="800" height="600" style="display: block; margin: 0 auto" }

The image was resized and centered properly, at least in my local VS markdown renderer.

Then, I have pushed changes to repo and unfortunately realized that it is not working for GitHub file. Nevertheless I will left this answer as it might help someone else.

So finally, I have ended up using good old HTML tag instead:

<img src="Image.svg" alt="Image" width="800" height="600" style="display: block; margin: 0 auto" />

But guess what? Some JS method replaced my style attribute! I have even tried class attribute and with the same result!

Then I have found following gist page where even more old-school HTML was used:

<p align="center">
    <img src="Image.svg" alt="Image" width="800" height="600" />

This one is working fine however, I would like to leave it without further comments...

How would you make a comma-separated string from a list of strings?

If you want to do the shortcut way :) :

','.join([str(word) for word in wordList])

But if you want to show off with logic :) :

wordList = ['USD', 'EUR', 'JPY', 'NZD', 'CHF', 'CAD']
stringText = ''

for word in wordList:
    stringText += word + ','

stringText = stringText[:-2]   # get rid of last comma

How do you receive a url parameter with a spring controller mapping

You should be using @RequestParam instead of @ModelAttribute, e.g.

public @ResponseBody int getAttr(@PathVariable(value="someID") String id, 
                                 @RequestParam String someAttr) {

You can even omit @RequestParam altogether if you choose, and Spring will assume that's what it is:

public @ResponseBody int getAttr(@PathVariable(value="someID") String id, 
                                 String someAttr) {

How to specify the bottom border of a <tr>?

You should define the style on the td element like so:

    <style type="text/css">
            border-bottom: solid 1px black;
                Test 1
            <td class="bb">
                Test 2

DISTINCT for only one column

When you use DISTINCT think of it as a distinct row, not column. It will return only rows where the columns do not match exactly the same.

SELECT DISTINCT ID, Email, ProductName, ProductModel
FROM Products

1 | [email protected] | ProductName1 | ProductModel1
2 | [email protected] | ProductName1 | ProductModel1

The query would return both rows because the ID column is different. I'm assuming that the ID column is an IDENTITY column that is incrementing, if you want to return the last then I recommend something like this:

SELECT DISTINCT TOP 1 ID, Email, ProductName, ProductModel
FROM Products

The TOP 1 will return only the first record, by ordering it by the ID descending it will return the results with the last row first. This will give you the last record.

How to redirect the output of the time command to a file in Linux?


{ time sleep 1 ; } 2> time.txt

which combines the STDERR of "time" and your command into time.txt

Or use

{ time sleep 1 2> sleep.stderr ; } 2> time.txt

which puts STDERR from "sleep" into the file "sleep.stderr" and only STDERR from "time" goes into "time.txt"

Can RDP clients launch remote applications and not desktops

This is called RemoteApp. To use it you need to install Terminal Services, which is now called Remote Desktop Services.

how to remove css property using javascript?

actually, if you already know the property, this will do it...

for example:

<a href="test.html" style="color:white;zoom:1.2" id="MyLink"></a>

    var txt = "";
    txt = getStyle(InterTabLink);
    setStyle(InterTabLink, txt.replace("zoom\:1\.2\;","");

    function setStyle(element, styleText){
  "cssText", styleText );
            element.setAttribute("style", styleText );

    /* getStyle function */
    function getStyle(element){
        var styleText = element.getAttribute('style');
        if(styleText == null)
            return "";
        if (typeof styleText == 'string') // !IE
            return styleText;
        else  // IE
            return styleText.cssText;

Note that this only works for inline styles... not styles you've specified through a class or something like that...

Other note: you may have to escape some characters in that replace statement, but you get the idea.

Font Awesome 5 font-family issue

Using the fontawesome-all.css file: Changing the "Brands" font-family from "Font Awesome 5 Free" to "Font Awesome 5 Brands" fixed the issues I was having.

I can't take all of the credit - I fixed my own local issue right before looking at the CDN version:

They've got the issue sorted out on the CDN as well.

 @font-face {_x000D_
    font-family: 'Font Awesome 5 Brands';_x000D_
    font-style: normal;_x000D_
    font-weight: normal;_x000D_
    src: url("../webfonts/fa-brands-400.eot");_x000D_
    src: url("../webfonts/fa-brands-400.eot?#iefix") format("embedded-opentype"), url("../webfonts/fa-brands-400.woff2") format("woff2"), url("../webfonts/fa-brands-400.woff") format("woff"), url("../webfonts/fa-brands-400.ttf") format("truetype"), url("../webfonts/fa-brands-400.svg#fontawesome") format("svg"); }_x000D_
    .fab {_x000D_
    font-family: 'Font Awesome 5 Brands'; }_x000D_
    @font-face {_x000D_
    font-family: 'Font Awesome 5 Brands';_x000D_
    font-style: normal;_x000D_
    font-weight: 400;_x000D_
    src: url("../webfonts/fa-regular-400.eot");_x000D_
  src: url("../webfonts/fa-regular-400.eot?#iefix") format("embedded-opentype"), url("../webfonts/fa-regular-400.woff2") format("woff2"), url("../webfonts/fa-regular-400.woff") format("woff"), url("../webfonts/fa-regular-400.ttf") format("truetype"), url("../webfonts/fa-regular-400.svg#fontawesome") format("svg"); }

python uninstall

If you still have files that are supposed to be deleted after re-installing a package, make sure the folder build is also deleted. Therefore, assuming that pkg is the package you want to delete:

rm -r $(python3 -c "import pkg; print(pkg.__path__[0] + '*' )") 
rm -rf build

Obove work out for python3 and delete the package and its *.egg-info file

Easy way to concatenate two byte arrays

byte[] result = new byte[a.length + b.length];
// copy a to result
System.arraycopy(a, 0, result, 0, a.length);
// copy b to result
System.arraycopy(b, 0, result, a.length, b.length);

How do I create a datetime in Python from milliseconds?

Just convert it to timestamp


Session timeout in ASP.NET

Are you using Forms authentication?

Forms authentication uses it own value for timeout (30 min. by default). A forms authentication timeout will send the user to the login page with the session still active. This may look like the behavior your app gives when session times out making it easy to confuse one with the other.

    <authentication mode="Forms">
          <forms timeout="50"/>

    <sessionState timeout="60"  />

Setting the forms timeout to something less than the session timeout can give the user a window in which to log back in without losing any session data.

Display an image with Python

Using opencv-python is faster for more operation on image:

import cv2
import matplotlib.pyplot as plt

im = cv2.imread('image.jpg')
im_resized = cv2.resize(im, (224, 224), interpolation=cv2.INTER_LINEAR)

plt.imshow(cv2.cvtColor(im_resized, cv2.COLOR_BGR2RGB))

How to break out of jQuery each Loop

I created a Fiddle for the answer to this question because the accepted answer is incorrect plus this is the first StackOverflow thread returned from Google regarding this question.

To break out of a $.each you must use return false;

Here is a Fiddle proving it:

Maven error: Not authorized, ReasonPhrase:Unauthorized

I have recently encountered this problem. Here are the steps to resolve

  1. Check the servers section in the settings.xml file.Is username and password correct?


  1. Check the repository section in the pom.xml file.The id of the server tag should be the same as the id of the repository tag.

   <id>serverId</id>  _x000D_

  1. If the repository tag is not configured in the pom.xml file, look in the settings.xml file.


Note that you should ensure that the id of the server tag should be the same as the id of the repository tag.

What is the http-header "X-XSS-Protection"?

This header is getting somehow deprecated. You can read more about it here - X-XSS-Protection

  • Chrome has removed their XSS Auditor
  • Firefox has not, and will not implement X-XSS-Protection
  • Edge has retired their XSS filter

This means that if you do not need to support legacy browsers, it is recommended that you use Content-Security-Policy without allowing unsafe-inline scripts instead.

ActiveX component can't create object

It really looks as though the object you are referencing is not registered on the system. I know you said it's installed, but that doesn't necessarily mean it's registered. To confirm this, search for the progID that you used in your registry.

Example for this code:

set objFSO = CreateObject("Scripting.FileSystemObject") 

I would search for Scripting.FileSystemObject in the registry. Then I would look at registry key above the found value, for InProcServer32 value. This will give you the path to the ActiveX file that it was registered from (for Scripting.FileSystemObject the file is "c:\windows\system32\scrrun.dll").

If you can't find your progID in the registry, then it's not registered on your system which is your problem. If it's not registered you need to find out what file registers it, which is usually an .ocx or a .dll in the same folder path of your third party app, and then register these file(s). Here is the command to register a file:

regsvr32 /i "c:\windows\system32\scrrun.dll"

Even if you find the progID value in the registry and it references a file that is present on your system, you may still want to try re-registering the file. I have found that sometimes the registration got broken somehow somewhere and it was easier to re-register the files then it was to fix the issue.

Include CSS,javascript file in Yii Framework

To include JS and CSS files in a specific view you can do it via controller by passing the parameters false, true, which will include the CSS and JS for, e.g.:

        'model' => $model,

How can I disable the default console handler, while using the java logging API?

This is strange but Logger.getLogger("global") does not work in my setup (as well as Logger.getLogger(Logger.GLOBAL_LOGGER_NAME)).

However Logger.getLogger("") does the job well.

Hope this info also helps somebody...

How can I get javascript to read from a .json file?


If you have your JSON as a string, JSON.parse() will work fine. Since you are loading the json from a file, you will need to do a XMLHttpRequest to it. For example (This is example):

var xmlhttp = new XMLHttpRequest();_x000D_
xmlhttp.onreadystatechange = function() {_x000D_
    if (this.readyState == 4 && this.status == 200) {_x000D_
        var myObj = JSON.parse(this.responseText);_x000D_
        document.getElementById("demo").innerHTML =;_x000D_
};_x000D_"GET", "json_demo.txt", true);_x000D_
<!DOCTYPE html>_x000D_
<h2>Use the XMLHttpRequest to get the content of a file.</h2>_x000D_
<p>The content is written in JSON format, and can easily be converted into a JavaScript object.</p>_x000D_
<p id="demo"></p>_x000D_
<p>Take a look at <a href="json_demo.txt" target="_blank">json_demo.txt</a></p>_x000D_

It will not work here as that file isn't located here. Go to this w3schools example though:

Here is the documentation for JSON.parse():

Here's a summary:

The JSON.parse() method parses a JSON string, constructing the JavaScript value or object described by the string. An optional reviver function can be provided to perform a transformation on the resulting object before it is returned.

Here's the example used:

var json = '{"result":true, "count":42}';_x000D_
obj = JSON.parse(json);_x000D_
// expected output: 42_x000D_
// expected output: true

Here is a summary on XMLHttpRequests from

Use XMLHttpRequest (XHR) objects to interact with servers. You can retrieve data from a URL without having to do a full page refresh. This enables a Web page to update just part of a page without disrupting what the user is doing. XMLHttpRequest is used heavily in Ajax programming.

If you don't want to use XMLHttpRequests, then a JQUERY way (which I'm not sure why it isn't working for you) is

Since it isn't working, I'd try using XMLHttpRequests

You could also try AJAX requests:

    'async': false,
    'global': false,
    'url': "/jsonfile.json",
    'dataType': "json",
    'success': function (data) {
        // do stuff with data


Could not find server 'server name' in sys.servers. SQL Server 2014

I had the problem due to an extra space in the name of the linked server. "SERVER1, 1234" instead of "SERVER1,1234"

Hexadecimal to Integer in Java

you can use this method : it's converting perfectly any hexadecimal number (presented as a string) to a decimal number

Java ArrayList of Doubles

You can use Arrays.asList to get some list (not necessarily ArrayList) and then use addAll() to add it to an ArrayList:

new ArrayList<Double>().addAll(Arrays.asList(1.38L, 2.56L, 4.3L));

If you're using Java6 (or higher) you can also use the ArrayList constructor that takes another list:

new ArrayList<Double>(Arrays.asList(1.38L, 2.56L, 4.3L));

Need to ZIP an entire directory using Node.js

I ended up using archiver lib. Works great.


var file_system = require('fs');
var archiver = require('archiver');

var output = file_system.createWriteStream('');
var archive = archiver('zip');

output.on('close', function () {
    console.log(archive.pointer() + ' total bytes');
    console.log('archiver has been finalized and the output file descriptor has closed.');

archive.on('error', function(err){
    throw err;


// append files from a sub-directory, putting its contents at the root of archive, false);

// append files from a sub-directory and naming it `new-subdir` within the archive'subdir/', 'new-subdir');


favicon.png vs favicon.ico - why should I use PNG instead of ICO?

PNG has 2 advantages: it has smaller size and it's more widely used and supported (except in case favicons). As mentioned before ICO, can have multiple size icons, which is useful for desktop applications, but not too much for websites. I would recommend you to put a favicon.ico in the root of your application. An if you have access to the Head of your website pages use the tag to point to a png file. So older browser will show the favicon.ico and newer ones the png.

To create Png and Icon files I would recommend The Gimp.

Find the division remainder of a number

26 % 7 (you will get remainder)

26 / 7 (you will get divisor can be float value )

26 // 7 (you will get divisor only integer value) )

Add centered text to the middle of a <hr/>-like line

Looking at above, I modified to:


.divider {
    font: 33px sans-serif;
    margin-top: 30px;
    text-transform: uppercase;
.divider span {
.divider span:before, .divider span:after {
    border-top: 2px solid #000;
    position: absolute;
    top: 15px;
    right: 10em;
    bottom: 0;
    width: 80%;
.divider span:after {
    position: absolute;
    top: 15px;
    bottom: 0;


<div class="divider">
    <span>This is your title</span></div>

Seems to work fine.

Linq to Entities join vs groupjoin

Let's suppose you have two different classes:

public class Person
    public string Name, Email;
    public Person(string name, string email)
        Name = name;
        Email = email;
class Data
    public string Mail, SlackId;
    public Data(string mail, string slackId)
        Mail = mail;
        SlackId = slackId;

Now, let's Prepare data to work with:

var people = new Person[]
        new Person("Sudi", "[email protected]"),
        new Person("Simba", "[email protected]"),
        new Person("Sarah", string.Empty)
    var records = new Data[]
        new Data("[email protected]", "Sudi_Try"),
        new Data("[email protected]", "Sudi@Test"),
        new Data("[email protected]", "SimbaLion")

You will note that [email protected] has got two slackIds. I have made that for demonstrating how Join works.

Let's now construct the query to join Person with Data:

var query = people.Join(records,
        x => x.Email,
        y => y.Mail,
        (person, record) => new { Name = person.Name, SlackId = record.SlackId});

After constructing the query, you could also iterate over it with a foreach like so:

foreach (var item in query)
        Console.WriteLine($"{item.Name} has Slack ID {item.SlackId}");

Let's also output the result for GroupJoin:

            x => x.Email,
            y => y.Mail,
            (person, recs) => new {
                Name = person.Name,
                SlackIds = recs.Select(r => r.SlackId).ToArray() // You could materialize //whatever way you want.

You will notice that the GroupJoin will put all SlackIds in a single group.

Need table of key codes for android and presenter

This is so out of date, but in case someone googles this, I have the same issue and figured it out.

If you use KeyEvent Viewer, volume up has a code=24, but a scanCode of 115.

Now my USB controller, only has code=# and all scanCodes are 0. But my airmouse (Mele F10) has all keys with codes and scan codes, but the scancode is what you have to put in the .kl file.

Hope this helps someone out there.

Query to check index on a table

On SQL Server, this will list all the indexes for a specified table:

select * from sys.indexes
where object_id = (select object_id from sys.objects where name = 'MYTABLE')

This query will list all tables without an index:

FROM sys.tables 
WHERE OBJECTPROPERTY(object_id,'IsIndexed') = 0

And this is an interesting MSDN FAQ on a related subject:
Querying the SQL Server System Catalog FAQ

WebDriver - wait for element using Java

Above wait statement is a nice example of Explicit wait.

As Explicit waits are intelligent waits that are confined to a particular web element(as mentioned in above x-path).

By Using explicit waits you are basically telling WebDriver at the max it is to wait for X units(whatever you have given as timeoutInSeconds) of time before it gives up.

How to remove array element in mongodb?

To remove all array elements irrespective of any given id, use this:

  { },
  { $pull: { '': { number: '+1786543589455' } } }

Difference between onCreate() and onStart()?

Take a look on life cycle of Activity enter image description here



Called when the activity is first created. This is where you should do all of your normal static set up: create views, bind data to lists, etc. This method also provides you with a Bundle containing the activity's previously frozen state, if there was one. Always followed by onStart().


Called when the activity is becoming visible to the user. Followed by onResume() if the activity comes to the foreground, or onStop() if it becomes hidden.

And you can write your simple class to take a look when these methods call

public class TestActivity extends Activity {
    /** Called when the activity is first created. */

    private final static String TAG = "TestActivity";

    public void onCreate(Bundle savedInstanceState) {
        Log.i(TAG, "On Create .....");
    /* (non-Javadoc)
    * @see
    protected void onDestroy() { 
        Log.i(TAG, "On Destroy .....");
    /* (non-Javadoc)
    * @see
    protected void onPause() { 
        Log.i(TAG, "On Pause .....");

    /* (non-Javadoc)
    * @see
    protected void onRestart() {
        Log.i(TAG, "On Restart .....");

    /* (non-Javadoc)
    * @see
    protected void onResume() {
        Log.i(TAG, "On Resume .....");

    /* (non-Javadoc)
    * @see
    protected void onStart() {
        Log.i(TAG, "On Start .....");
    /* (non-Javadoc)
    * @see
    protected void onStop() {
        Log.i(TAG, "On Stop .....");

Hope this will clear your confusion.

And take a look here for details.

Lifecycle Methods in Details is a very good example and demo application, which is a very good article to understand the life cycle.

PHP Parse error: syntax error, unexpected T_PUBLIC

You can remove public keyword from your functions, because, you have to define a class in order to declare public, private or protected function

How do you round a floating point number in Perl?

See perldoc/perlfaq:

Remember that int() merely truncates toward 0. For rounding to a certain number of digits, sprintf() or printf() is usually the easiest route.

 # prints 3.142

The POSIX module (part of the standard Perl distribution) implements ceil(), floor(), and a number of other mathematical and trigonometric functions.

use POSIX;
$ceil  = ceil(3.5); # 4
$floor = floor(3.5); # 3

In 5.000 to 5.003 perls, trigonometry was done in the Math::Complex module.

With 5.004, the Math::Trig module (part of the standard Perl distribution) > implements the trigonometric functions.

Internally it uses the Math::Complex module and some functions can break out from the real axis into the complex plane, for example the inverse sine of 2.

Rounding in financial applications can have serious implications, and the rounding method used should be specified precisely. In these cases, it probably pays not to trust whichever system rounding is being used by Perl, but to instead implement the rounding function you need yourself.

To see why, notice how you'll still have an issue on half-way-point alternation:

for ($i = 0; $i < 1.01; $i += 0.05)
   printf "%.1f ",$i

0.0 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.4 0.4 0.5 0.5 0.6 0.7 0.7 0.8 0.8 0.9 0.9 1.0 1.0

Don't blame Perl. It's the same as in C. IEEE says we have to do this. Perl numbers whose absolute values are integers under 2**31 (on 32 bit machines) will work pretty much like mathematical integers. Other numbers are not guaranteed.

Random record from MongoDB

Now you can use the aggregate. Example:

   [ { $sample: { size: 3 } } ]

See the doc.

Linux command (like cat) to read a specified quantity of characters



head - output the first part of files


head [OPTION]... [FILE]...


Print the first 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input.

Mandatory arguments to long options are mandatory for short options too.
-c, --bytes=[-]N print the first N bytes of each file; with the leading '-', print all but the last N bytes of each file

CSS3 Transition - Fade out effect

    background-color: rgba(255, 0, 0, 0.83);
    border-radius: 8px;
    box-shadow: silver 3px 3px 5px 0px;
    border: 2px dashed yellow;
    padding: 3px;
    transition: all 1s ease-in-out;
    background-color: rgba(255, 0, 0, 0.0);
    box-shadow: none;
    border: 0px dashed yellow;
    border-radius: 0px;

demo here.

Quickly getting to YYYY-mm-dd HH:MM:SS in Perl

Use strftime in the standard POSIX module. The arguments to strftime in Perl’s binding were designed to align with the return values from localtime and gmtime. Compare

strftime(fmt, sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1)


my          ($sec,$min,$hour,$mday,$mon,$year,$wday,     $yday,     $isdst) = gmtime(time);

Example command-line use is

$ perl -MPOSIX -le 'print strftime "%F %T", localtime $^T'

or from a source file as in

use POSIX;

print strftime "%F %T", localtime time;

Some systems do not support the %F and %T shorthands, so you will have to be explicit with

print strftime "%Y-%m-%d %H:%M:%S", localtime time;


print strftime "%Y-%m-%d %H:%M:%S", gmtime time;

Note that time returns the current time when called whereas $^T is fixed to the time when your program started. With gmtime, the return value is the current time in GMT. Retrieve time in your local timezone with localtime.

What does the symbol \0 mean in a string-literal?

Banging my usual drum solo of JUST TRY IT, here's how you can answer questions like that in the future:

$ cat junk.c
#include <stdio.h>

char* string = "Hello\0";

int main(int argv, char** argc)
    printf("-->%s<--\n", string);
$ gcc -S junk.c
$ cat junk.s

... eliding the unnecessary parts ...

    .string "Hello"
    .string ""


    .string "-->%s<--\n"


Note here how the string I used for printf is just "-->%s<---\n" while the global string is in two parts: "Hello" and "". The GNU assembler also terminates strings with an implicit NUL character, so the fact that the first string (.LC0) is in those two parts indicates that there are two NULs. The string is thus 7 bytes long. Generally if you really want to know what your compiler is doing with a certain hunk of code, isolate it in a dummy example like this and see what it's doing using -S (for GNU -- MSVC has a flag too for assembler output but I don't know it off-hand). You'll learn a lot about how your code works (or fails to work as the case may be) and you'll get an answer quickly that is 100% guaranteed to match the tools and environment you're working in.

Call to undefined function App\Http\Controllers\ [ function name ]

say you define the static getFactorial function inside a CodeController

then this is the way you need to call a static function, because static properties and methods exists with in the class, not in the objects created using the class.



To best practice I think you can put this kind of functions inside a separate file so you can maintain with more easily.

to do that

create a folder inside app directory and name it as lib (you can put a name you like).

this folder to needs to be autoload to do that add app/lib to composer.json as below. and run the composer dumpautoload command.

"autoload": {
    "classmap": [

then files inside lib will autoloaded.

then create a file inside lib, i name it helperFunctions.php

inside that define the function.

if ( ! function_exists('getFactorial'))

     * return the factorial of a number
     * @param $number
     * @return string
    function getFactorial($date)
        $fact = 1;

        for($i = 1; $i <= $num ;$i++)
            $fact = $fact * $i;

        return $fact;


and call it anywhere within the app as

$fatorial_value = getFactorial(225);

What causes javac to issue the "uses unchecked or unsafe operations" warning

The "unchecked or unsafe operations" warning was added when java added Generics, if I remember correctly. It's usually asking you to be more explicit about types, in one way or another.

For example. the code ArrayList foo = new ArrayList(); triggers that warning because javac is looking for ArrayList<String> foo = new ArrayList<String>();

How do I create a random alpha-numeric string in C++?

 void gen_random(char *s, size_t len) {
     for (size_t i = 0; i < len; ++i) {
         int randomChar = rand()%(26+26+10);
         if (randomChar < 26)
             s[i] = 'a' + randomChar;
         else if (randomChar < 26+26)
             s[i] = 'A' + randomChar - 26;
             s[i] = '0' + randomChar - 26 - 26;
     s[len] = 0;

How to set a default value in react-select

Use defaultInputValue props like so:

   placeholder="Brand Name"


for more reference

How to generate .angular-cli.json file in Angular Cli?

In Angular 6, .angular-cli.json has been replaced with angular.json

For Angular < 6:

Create a new file with name '.angular-cli.json' and add this file in your main directory.

  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
  "project": {
    "name": "my-app"
  "apps": [
      "root": "src",
      "outDir": "dist",
      "assets": [
      "index": "index.html",
      "main": "main.ts",
      "polyfills": "polyfills.ts",
      "test": "test.ts",
      "tsconfig": "",
      "testTsconfig": "tsconfig.spec.json",
      "prefix": "app",
      "styles": [
      "scripts": [],
      "environmentSource": "environments/environment.ts",
      "environments": {
        "dev": "environments/environment.ts",
        "prod": "environments/"
  "e2e": {
    "protractor": {
      "config": "./protractor.conf.js"
  "lint": [
      "project": "src/",
      "exclude": "**/node_modules/**"
      "project": "src/tsconfig.spec.json",
      "exclude": "**/node_modules/**"
      "project": "e2e/tsconfig.e2e.json",
      "exclude": "**/node_modules/**"
  "test": {
    "karma": {
      "config": "./karma.conf.js"
  "defaults": {
    "styleExt": "css",
    "component": {}

Get file size, image width and height before upload

So I started experimenting with the different things that FileReader API had to offer and could create an IMG tag with a DATA URL.

Drawback: It doesn't work on mobile phones, but it works fine on Google Chrome.

$('input').change(function() {_x000D_
    var fr = new FileReader;_x000D_
    fr.onload = function() {_x000D_
        var img = new Image;_x000D_
        img.onload = function() { _x000D_
//I loaded the image and have complete control over all attributes, like width and src, which is the purpose of filereader._x000D_
            $.ajax({url: img.src, async: false, success: function(result){_x000D_
              $("#result").html("READING IMAGE, PLEASE WAIT...")_x000D_
              $("#result").html("<img src='" + img.src + "' />");_x000D_
                console.log("Finished reading Image");_x000D_
        img.src = fr.result;_x000D_
<script src=""></script>_x000D_
<input type="file" accept="image/*" capture="camera">_x000D_
<div id='result'>Please choose a file to view it. <br/>(Tested successfully on Chrome - 100% SUCCESS RATE)</div>

(see this on a jsfiddle at
(see the original jsfiddle that i added upon to at

What is the "__v" field in Mongoose

We can use versionKey: false in Schema definition

'use strict';

const mongoose = require('mongoose');

export class Account extends mongoose.Schema {

    constructor(manager) {

        var trans = {
            tran_date: Date,
            particulars: String,
            debit: Number,
            credit: Number,
            balance: Number

            account_number: Number,
            account_name: String,
            ifsc_code: String,
            password: String,
            currency: String,
            balance: Number,
            beneficiaries: Array,
            transaction: [trans]
        }, {
            versionKey: false // set to false then it wont create in mongodb

        this.pre('remove', function(next) {
                    _id: {
                        $in: this.beneficiaries


How to send parameters from a notification-click to an activity?

Take a look at this guide (creating a notification) and to samples ApiDemos "StatusBarNotifications" and "NotificationDisplay".

For managing if the activity is already running you have two ways:

  1. Add FLAG_ACTIVITY_SINGLE_TOP flag to the Intent when launching the activity, and then in the activity class implement onNewIntent(Intent intent) event handler, that way you can access the new intent that was called for the activity (which is not the same as just calling getIntent(), this will always return the first Intent that launched your activity.

  2. Same as number one, but instead of adding a flag to the Intent you must add "singleTop" in your activity AndroidManifest.xml.

If you use intent extras, remeber to call PendingIntent.getActivity() with the flag PendingIntent.FLAG_UPDATE_CURRENT, otherwise the same extras will be reused for every notification.

Can't find AVD or SDK manager in Eclipse

Unfortunately I ended up having to re-install eclipse. but first (In Linux)(not sure of folder in Windows) do:

sudo rm -R /usr/share/eclipse/

Add new value to an existing array in JavaScript

You can use the .push() method (which is standard JavaScript)


var primates = new Array();

How should I call 3 functions in order to execute them one after the other?

I use a 'waitUntil' function based on javascript's setTimeout

    funcCond : function to call to check whether a condition is true
    readyAction : function to call when the condition was true
    checkInterval : interval to poll <optional>
    timeout : timeout until the setTimeout should stop polling (not 100% accurate. It was accurate enough for my code, but if you need exact milliseconds, please refrain from using Date <optional>
    timeoutfunc : function to call on timeout <optional>
function waitUntil(funcCond, readyAction, checkInterval, timeout, timeoutfunc) {
    if (checkInterval == null) {
        checkInterval = 100; // checkinterval of 100ms by default
    var start = +new Date(); // use the + to convert it to a number immediatly
    if (timeout == null) {
        timeout = Number.POSITIVE_INFINITY; // no timeout by default
    var checkFunc = function() {
        var end = +new Date(); // rough timeout estimations by default

        if (end-start > timeout) {
            if (timeoutfunc){ // if timeout function was defined
                timeoutfunc(); // call timeout function
        } else {
            if(funcCond()) { // if condition was met
                readyAction(); // perform ready action function
            } else {
                setTimeout(checkFunc, checkInterval); // else re-iterate
    checkFunc(); // start check function initially

This would work perfectly if your functions set a certain condition to true, which you would be able to poll. Plus it comes with timeouts, which offers you alternatives in case your function failed to do something (even within time-range. Think about user feedback!)


waitUntil(function() { return doSomething_value===1;}, doSomethingElse);
waitUntil(function() { return doSomethingElse_value===1;}, doSomethingUseful);


Date causes rough timeout estimates. For greater precision, switch to functions such as console.time(). Do take note that Date offers greater cross-browser and legacy support. If you don't need exact millisecond measurements; don't bother, or, alternatively, wrap it, and offer console.time() when the browser supports it

Best Timer for using in a Windows service

I agree with previous comment that might be best to consider a different approach. My suggest would be write a console application and use the windows scheduler:

This will:

  • Reduce plumbing code that replicates scheduler behaviour
  • Provide greater flexibility in terms of scheduling behaviour (e.g. only run on weekends) with all scheduling logic abstracted from application code
  • Utilise the command line arguments for parameters without having to setup configuration values in config files etc
  • Far easier to debug/test during development
  • Allow a support user to execute by invoking the console application directly (e.g. useful during support situations)

Why can't I inherit static classes?

When we create a static class that contains only the static members and a private constructor.The only reason is that the static constructor prevent the class from being instantiated for that we can not inherit a static class .The only way to access the member of the static class by using the class name itself.Try to inherit a static class is not a good idea.

Perform an action in every sub-directory using Bash

find . -type d -print0 | xargs -0 -n 1 my_command

JQuery window scrolling event?

Check if the user has scrolled past the header ad, then display the footer ad.

if($(your header ad).position().top < 0) { $(your footer ad).show() }

Am I correct at what you are looking for?

Project Links do not work on Wamp Server

Hello you need to open the index.php from the wamp server and change $suppress_localhost = false; from $suppress_localhost = true; then your wamp will working fine

Removing MySQL 5.7 Completely

You need to remove the /var/lib/mysql folder. Also, purge when you remove the packages (I'm told this helps).

sudo apt-get remove --purge mysql-server mysql-client mysql-common

sudo rm -rf /var/lib/mysql

I was encountering similar issues. The second line got rid of my issues and allowed me to set up MySql from scratch. Hopefully it helps you too!

How to get all properties values of a JavaScript Object (without knowing the keys)?

Here's a function similar to PHP's array_values()

function array_values(input) {
  var output = [], key = '';
  for ( key in input ) { output[output.length] = input[key]; }
  return output;

Here's how to get the object's values if you're using ES6 or higher:


Display QImage with QtGui

Simple, but complete example showing how to display QImage might look like this:

#include <QtGui/QApplication>
#include <QLabel>

int main(int argc, char *argv[])
    QApplication a(argc, argv);

    QImage myImage;

    QLabel myLabel;

    return a.exec();

SQLite Reset Primary Key Field

You can reset by update sequence after deleted rows in your-table


SQL Server Case Statement when IS NULL

  case isnull(B.[stat],0)
  when 0 then dateadd(dd,10,(c.[Eventdate]))

you can add in else statement if you want to add 30 days to the same .

Django gives Bad Request (400) when DEBUG = False

Navigate to settings and locate the file Set the allowed hosts to ALLOWED_HOSTS = ['*']

Rebuild all indexes in a Database

Replace the "YOUR DATABASE NAME" in the query below.

    DECLARE @Database NVARCHAR(255)   
    DECLARE @Table NVARCHAR(255)  
    DECLARE @cmd NVARCHAR(1000)  

    SELECT name FROM master.sys.databases   
    WHERE name IN ('YOUR DATABASE NAME')  -- databases
    AND state = 0 -- database is online
    AND is_in_standby = 0 -- database is not read only for log shipping
    ORDER BY 1  

    OPEN DatabaseCursor  

    FETCH NEXT FROM DatabaseCursor INTO @Database  

       SET @cmd = 'DECLARE TableCursor CURSOR READ_ONLY FOR SELECT ''['' + table_catalog + ''].['' + table_schema + ''].['' +  
       table_name + '']'' as tableName FROM [' + @Database + '].INFORMATION_SCHEMA.TABLES WHERE table_type = ''BASE TABLE'''   

       -- create table cursor  
       EXEC (@cmd)  
       OPEN TableCursor   

       FETCH NEXT FROM TableCursor INTO @Table   
       WHILE @@FETCH_STATUS = 0   
          BEGIN TRY   
             SET @cmd = 'ALTER INDEX ALL ON ' + @Table + ' REBUILD' 
             PRINT @cmd -- uncomment if you want to see commands
             EXEC (@cmd) 
          END TRY
          BEGIN CATCH
             PRINT '---'
             PRINT @cmd
             PRINT ERROR_MESSAGE() 
             PRINT '---'
          END CATCH

          FETCH NEXT FROM TableCursor INTO @Table   

       CLOSE TableCursor   
       DEALLOCATE TableCursor  

       FETCH NEXT FROM DatabaseCursor INTO @Database  
    CLOSE DatabaseCursor   
    DEALLOCATE DatabaseCursor

How to check Spark Version

According to the Cloudera documentation - What's New in CDH 5.7.0 it includes Spark 1.6.0.

Factory Pattern. When to use factory methods?

It is important to clearly differentiate the idea behind using factory or factory method. Both are meant to address mutually exclusive different kind of object creation problems.

Let's be specific about "factory method":

First thing is that, when you are developing library or APIs which in turn will be used for further application development, then factory method is one of the best selections for creation pattern. Reason behind; We know that when to create an object of required functionality(s) but type of object will remain undecided or it will be decided ob dynamic parameters being passed.

Now the point is, approximately same can be achieved by using factory pattern itself but one huge drawback will introduce into the system if factory pattern will be used for above highlighted problem, it is that your logic of crating different objects(sub classes objects) will be specific to some business condition so in future when you need to extend your library's functionality for other platforms(In more technically, you need to add more sub classes of basic interface or abstract class so factory will return those objects also in addition to existing one based on some dynamic parameters) then every time you need to change(extend) the logic of factory class which will be costly operation and not good from design perspective. On the other side, if "factory method" pattern will be used to perform the same thing then you just need to create additional functionality(sub classes) and get it registered dynamically by injection which doesn't require changes in your base code.

interface Deliverable 

abstract class DefaultProducer 

    public void taskToBeDone() 
        Deliverable deliverable = factoryMethodPattern();
    protected abstract Deliverable factoryMethodPattern();

class SpecificDeliverable implements Deliverable 

class SpecificProducer extends DefaultProducer 
    protected Deliverable factoryMethodPattern() 
        return new SpecificDeliverable();

public class MasterApplicationProgram 
    public static void main(String arg[]) 
        DefaultProducer defaultProducer = new SpecificProducer();

Access PHP variable in JavaScript

I'm not sure how necessary this is, and it adds a call to getElementById, but if you're really keen on getting inline JavaScript out of your code, you can pass it as an HTML attribute, namely:

<span class="metadata" id="metadata-size-of-widget" title="<?php echo json_encode($size_of_widget) ?>"></span>

And then in your JavaScript:

var size_of_widget = document.getElementById("metadata-size-of-widget").title;

Python script header

From the manpage for env (GNU coreutils 6.10):

env - run a program in a modified environment

In theory you could use env to reset the environment (removing many of the existing environment variables) or add additional environment variables in the script header. Practically speaking, the two versions you mentioned are identical. (Though others have mentioned a good point: specifying python through env lets you abstractly specify python without knowing its path.)

How to get cookie's expire time

It seems there's a list of all cookies sent to browser in array returned by php's headers_list() which among other data returns "Set-Cookie" elements as follows:

Set-Cookie: cooke_name=cookie_value; expires=expiration_time; Max-Age=age; path=path; domain=domain

This way you can also get deleted ones since their value is deleted:

Set-Cookie: cooke_name=deleted; expires=expiration_time; Max-Age=age; path=path; domain=domain

From there on it's easy to retrieve expiration time or age for particular cookie. Keep in mind though that this array is probably available only AFTER actual call to setcookie() has been made so it's valid for script that has already finished it's job. I haven't tested this in some other way(s) since this worked just fine for me.

This is rather old topic and I'm not sure if this is valid for all php builds but I thought it might be helpfull.

For more info see:

Converting string to double in C#

You can try this example out. A simple C# progaram to convert string to double

class Calculations{

protected double length;
protected double height;
protected double width;

public void get_data(){

this.length = Convert.ToDouble(Console.ReadLine());
this.width  = Convert.ToDouble(Console.ReadLine());
this.height = Convert.ToDouble(Console.ReadLine());


What is the purpose of willSet and didSet in Swift?

I do not know C#, but with a little guesswork I think I understand what

foo : int {
    get { return getFoo(); }
    set { setFoo(newValue); }

does. It looks very similar to what you have in Swift, but it's not the same: in Swift you do not have the getFoo and setFoo. That is not a little difference: it means you do not have any underlying storage for your value.

Swift has stored and computed properties.

A computed property has get and may have set (if it's writable). But the code in the getter and setter, if they need to actually store some data, must do it in other properties. There is no backing storage.

A stored property, on the other hand, does have backing storage. But it does not have get and set. Instead it has willSet and didSet which you can use to observe variable changes and, eventually, trigger side effects and/or modify the stored value. You do not have willSet and didSet for computed properties, and you do not need them because for computed properties you can use the code in set to control changes.

How to change bower's default components folder?

Hi i am same problem and resolve this ways.

windows user and vs cant'create .bowerrc file.

in cmd go any folder

install any packages which is contains .bowerrc file forexample

bower install angular-local-storage

this plugin contains .bowerrc file. copy that and go to your project and paste this file.

and in visual studio - solution explorer - show all files and include project seen .bowerrc file

i resolve this ways :)

Spring MVC - Why not able to use @RequestBody and @RequestParam together

You could also just change the @RequestParam default required status to false so that HTTP response status code 400 is not generated. This will allow you to place the Annotations in any order you feel like.

@RequestParam(required = false)String name

Find the number of employees in each department - SQL Oracle

Try the query below:

select count(*),d.dname from emp e , dept d where d.deptno = e.deptno
group by d.dname

how to install gcc on windows 7 machine?

I use msysgit to install gcc on Windows, it has a nice installer which installs most everything that you might need. Most devs will need more than just the compiler, e.g. the shell, shell tools, make, git, svn, etc. msysgit comes with all of that.

edit: I am now using msys2. Msys2 uses pacman from Arch Linux to install packages, and includes three environments, for building msys2 apps, 32-bit native apps, and 64-bit native apps. (You probably want to build 32-bit native apps.)

You could also go full-monty and install code::blocks or some other gui editor that comes with a compiler. I prefer to use vim and make.

curl error 18 - transfer closed with outstanding read data remaining

I got this error when my server ran out of disk space and closed the connection midway during generating the response and simply closed the connection

"Parameter not valid" exception loading System.Drawing.Image

This error is caused by binary data being inserted into a buffer. To solve this problem, you should insert one statement in your code.

This statement is:

obj_FileStream.Read(Img, 0, Convert.ToInt32(obj_FileStream.Length));


FileStream obj_FileStream = new FileStream(str_ImagePath, FileMode.OpenOrCreate, FileAccess.Read);
Byte[] Img = new Byte[obj_FileStream.Length];
obj_FileStream.Read(Img, 0, Convert.ToInt32(obj_FileStream.Length));         
dt_NewsFeedByRow.Rows[0][6] = Img;

How To Upload Files on GitHub

I didn't find the above answers sufficiently explicit, and it took me some time to figure it out for myself. The most useful page I found was:

I'm on a Unix box, using the command line. I expect this will all work on a Mac command line. (Mac or Window GUI looks to be available at but I haven't tested this, and don't know how transferable this will be to the GUI.)

Step 1: Create a Github account Step 2: Create a new repository, typically with a README and LICENCE file created in the process. Step 3: Install "git" software. (Links in answers above and online help at github should suffice to do these steps, so I don't provide detailed instructions.) Step 4: Tell git who you are:

git config --global "<NAME>"
git config --global "<email>"

I think the e-mail must be one of the addresses you have associated with the github account. I used the same name as I used in github, but I think (not sure) that this is not required. Optionally you can add caching of credentials, so you don't need to type in your github account name and password so often.

Create and navigate to some top level working directory:

mkdir <working>
cd <working>

Import the nearly empty repository from github:

git clone<user>/<repository>

This might ask for credentials (if github repository is not 'public'.) Move to directory, and see what we've done:

cd <repository>
ls -a
git remote -v

(The 'ls' and 'git remote' commands are optional, they just show you stuff) Copy the 10000 files and millions of lines of code that you want to put in the repository:

cp -R <path>/src .
git status -s

(assuming everything you want is under a directory named "src".) (The second command again is optional and just shows you stuff)

Add all the files you just copied to git, and optionally admire the the results:

git add src
git status -s

Commit all the changes:

git commit -m "<commit comment>"

Push the changes

git push origin master

"Origin" is an alias for your github repository which was automatically set up by the "git clone" command. "master" is the branch you are pushing to. Go look at github in your browser and you should see all the files have been added.

Optionally remove the directory you did all this in, to reclaim disk space:

cd ..
rm -r <working>

TypeError: $(...).autocomplete is not a function

you missed jquery ui library. Use CDN of Jquery UI or if you want it locally then download the file from Jquery Ui

<link href="" rel="Stylesheet"></link>
<script src="YourJquery source path"></script>
<script src="" ></script>

Can't run Curl command inside my Docker Container

curl: command not found

is a big hint, you have to install it with :

apt-get update; apt-get install curl

Entity Framework vs LINQ to SQL

I think if you need to develop something quick with no Strange things in the middle, and you need the facility to have entities representing your tables:

Linq2Sql can be a good allied, using it with LinQ unleashes a great developing timing.

How to extract a single value from JSON response?

using json.loads will turn your data into a python dictionary.

Dictionaries values are accessed using ['key']

resp_str = {
  "name" : "ns1:timeSeriesResponseType",
  "declaredType" : "org.cuahsi.waterml.TimeSeriesResponseType",
  "scope" : "javax.xml.bind.JAXBElement$GlobalScope",
  "value" : {
    "queryInfo" : {
      "creationTime" : 1349724919000,
      "queryURL" : "",
      "criteria" : {
        "locationParam" : "[ALL:103232434]",
        "variableParam" : "[00060, 00065]"
      "note" : [ {
        "value" : "[ALL:103232434]",
        "title" : "filter:sites"
      }, {
        "value" : "[mode=LATEST, modifiedSince=null]",
        "title" : "filter:timeRange"
      }, {
        "value" : "sdas01",
        "title" : "server"
      } ]
  "nil" : false,
  "globalScope" : true,
  "typeSubstituted" : false

would translate into a python diction

resp_dict = json.loads(resp_str)

resp_dict['name'] # "ns1:timeSeriesResponseType"

resp_dict['value']['queryInfo']['creationTime'] # 1349724919000

How do I create a file at a specific path?

f = open("", "a") Will be created in whatever directory the python file is run from.

I'm not sure about the other error...I don't work in windows.

How to refresh token with Google API client?

According to Authentication on google: OAuth2 keeps returning 'invalid_grant'

"You should reuse the access token you get after the first successful authentication. You will get an invalid_grant error if your previous token has not expired yet. Cache it somewhere so you can reuse it."

hope it helps

How to get the path of running java program

Try this code:

final File f = new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath());

replace 'MyClass' with your class containing the main method.

Alternatively you can also use


Above mentioned System property provides

Path used to find directories and JAR archives containing class files. Elements of the class path are separated by a platform-specific character specified in the path.separator property.

Disable the postback on an <ASP:LinkButton>

You might also want to have the client-side function return false.

<asp:LinkButton runat="server" id="button" Text="Click Me" OnClick="myfunction();return false;" AutoPostBack="false" />

You might also consider:

<span runat="server" id="clickableSpan" onclick="myfunction();" class="clickable">Click Me</span>

I use the clickable class to set things like pointer, color, etc. so that its appearance is similar to an anchor tag, but I don't have to worry about it getting posted back or having to do the href="javascript:void(0);" trick.

How to select last child element in jQuery?

If you want to select the last child and need to be specific on the element type you can use the selector last-of-type

Here is an example:

$("div p:last-of-type").css("border", "3px solid red");
$("div span:last-of-type").css("border", "3px solid red");

<div id="example">
            <p>This is paragraph 1</p>
            <p>This is paragraph 2</p>
            <span>This is paragraph 3</span>
            <span>This is paragraph 4</span>
            <p>This is paragraph 5</p>

In the example above both Paragraph 4 and Paragraph 5 will have a red border since Paragraph 5 is the last element of "p" type in the div and Paragraph 4 is the last "span" in the div.

How do I get an element to scroll into view, using jQuery?

Simple 2 steps for scrolling down to end or bottom.

Step1: get the full height of scrollable(conversation) div.

Step2: apply scrollTop on that scrollable(conversation) div using the value obtained in step1.

var fullHeight = $('#conversation')[0].scrollHeight;


Above steps must be applied for every append on the conversation div.

Is there any way to start with a POST request using Selenium?

Short answer: No.

But you might be able to do it with a bit of filthing. If you open up a test page (with GET) then evaluate some JavaScript on that page you should be able to replicate a POST request. See JavaScript post request like a form submit to see how you can replicate a POST request in JavaScript.

Hope this helps.

How to use vagrant in a proxy environment?

The question does not mention the VM Provider but in my case, I use Virtual Box under the same environment. There is an option in the Virtual Box GUI that I needed to enable in order to make it work. Is located in the Virtual Box app preferences: File >> Preferences... >> Proxy. Once I configured this, I was able to work without problems. Hope this tip can also help you guys.

Could not reliably determine the server's fully qualified domain name

Two things seemed to do it for me:

  1. Put all aliases for in /etc/hosts in a single line (e.g. localhost mysite.local myothersite.local
  2. Set ServerName in my httpd.conf to (localhost or didn't work for me)

Editing /etc/hosts got rid of long response times and setting the ServerName got rid of OP's warning for me.

Parse json string to find and element (key / value)

Use a JSON parser, like JSON.NET

string json = "{ \"Atlantic/Canary\": \"GMT Standard Time\", \"Europe/Lisbon\": \"GMT Standard Time\", \"Antarctica/Mawson\": \"West Asia Standard Time\", \"Etc/GMT+3\": \"SA Eastern Standard Time\", \"Etc/GMT+2\": \"UTC-02\", \"Etc/GMT+1\": \"Cape Verde Standard Time\", \"Etc/GMT+7\": \"US Mountain Standard Time\", \"Etc/GMT+6\": \"Central America Standard Time\", \"Etc/GMT+5\": \"SA Pacific Standard Time\", \"Etc/GMT+4\": \"SA Western Standard Time\", \"Pacific/Wallis\": \"UTC+12\", \"Europe/Skopje\": \"Central European Standard Time\", \"America/Coral_Harbour\": \"SA Pacific Standard Time\", \"Asia/Dhaka\": \"Bangladesh Standard Time\", \"America/St_Lucia\": \"SA Western Standard Time\", \"Asia/Kashgar\": \"China Standard Time\", \"America/Phoenix\": \"US Mountain Standard Time\", \"Asia/Kuwait\": \"Arab Standard Time\" }";
var data = (JObject)JsonConvert.DeserializeObject(json);
string timeZone = data["Atlantic/Canary"].Value<string>();

Jquery submit form

You can try like:

        //perform anythng

Or even you can try like

$(".nextbutton").click(function() { 

How do I pass a class as a parameter in Java?

I am not sure what you are trying to accomplish, but you may want to consider that passing a class may not be what you really need to be doing. In many cases, dealing with Class like this is easily encapsulated within a factory pattern of some type and the use of that is done through an interface. here's one of dozens of articles on that pattern:

using a class within a factory can be accomplished in a variety of ways, most notably by having a config file that contains the name of the class that implements the required interface. Then the factory can find that class from within the class path and construct it as an object of the specified interface.

Not able to access adb in OS X through Terminal, "command not found"

I couldn't get the stupid path working so I created an alias for abd

alias abd ="~/Library/Android/sdk/platform-tools/adb"

works fine.

How can I make a TextArea 100% width without overflowing when padding is present in CSS?

If you pad and offset it like this:

    border:1px solid #999999;
    padding: 7px 0 7px 7px; 
    position:relative; left:-8px; /* 1px border, too */

the right side of the textarea perfectly aligns with the right side of the container, and the text inside the textarea aligns perfectly with the body text in the container... and the left side of the textarea 'sticks out' a bit. it's sometimes prettier.

Getting output of system() calls in Ruby

As Simon Hürlimann already explained, Open3 is safer than backticks etc.

require 'open3'
output = Open3.popen3("ls") { |stdin, stdout, stderr, wait_thr| }

Note that the block form will auto-close stdin, stdout and stderr- otherwise they'd have to be closed explicitly.

How can I bind to the change event of a textarea in jQuery?

Try this

 $("textarea").bind('cut paste', function(e) { });

Angular 5 - Copy to clipboard

Use navigator.clipboard.writeText to copy the content to clipboard

navigator.clipboard.writeText(content).then().catch(e => console.error(e));

Import XXX cannot be resolved for Java SE standard classes

This is an issue relating JRE.In my case (eclipse Luna with Maven plugin, JDK 7) I solved this by making following change in pom.xml and then Maven Update Project.





Screenshot showing problem in JRE: enter image description here

How can I use numpy.correlate to do autocorrelation?

I'm a computational biologist, and when I had to compute the auto/cross-correlations between couples of time series of stochastic processes I realized that np.correlate was not doing the job I needed.

Indeed, what seems to be missing from np.correlate is the averaging over all the possible couples of time points at distance .

Here is how I defined a function doing what I needed:

def autocross(x, y):
    c = np.correlate(x, y, "same")
    v = [c[i]/( len(x)-abs( i - (len(x)/2)  ) ) for i in range(len(c))]
    return v

It seems to me none of the previous answers cover this instance of auto/cross-correlation: hope this answer may be useful to somebody working on stochastic processes like me.

The Use of Multiple JFrames: Good or Bad Practice?

It's been a while since the last time i touch swing but in general is a bad practice to do this. Some of the main disadvantages that comes to mind:

  • It's more expensive: you will have to allocate way more resources to draw a JFrame that other kind of window container, such as Dialog or JInternalFrame.

  • Not user friendly: It is not easy to navigate into a bunch of JFrame stuck together, it will look like your application is a set of applications inconsistent and poorly design.

  • It's easy to use JInternalFrame This is kind of retorical, now it's way easier and other people smarter ( or with more spare time) than us have already think through the Desktop and JInternalFrame pattern, so I would recommend to use it.

Python No JSON object could be decoded

It seems that you have invalid JSON. In that case, that's totally dependent on the data the server sends you which you have not shown. I would suggest running the response through a JSON validator.

Read a local text file using Javascript

You can use a FileReader object to read text file here is example code:

  <div id="page-wrapper">

        <h1>Text File Reader</h1>
            Select a text file: 
            <input type="file" id="fileInput">
        <pre id="fileDisplayArea"><pre>

window.onload = function() {
        var fileInput = document.getElementById('fileInput');
        var fileDisplayArea = document.getElementById('fileDisplayArea');

        fileInput.addEventListener('change', function(e) {
            var file = fileInput.files[0];
            var textType = /text.*/;

            if (file.type.match(textType)) {
                var reader = new FileReader();

                reader.onload = function(e) {
                    fileDisplayArea.innerText = reader.result;

            } else {
                fileDisplayArea.innerText = "File not supported!"


Here is the codepen demo

If you have a fixed file to read every time your application load then you can use this code :

var fileDisplayArea = document.getElementById('fileDisplayArea');
function readTextFile(file)
    var rawFile = new XMLHttpRequest();"GET", file, false);
    rawFile.onreadystatechange = function ()
        if(rawFile.readyState === 4)
            if(rawFile.status === 200 || rawFile.status == 0)
                var allText = rawFile.responseText;
                fileDisplayArea.innerText = allText 


Better way to find last used row

How is this?

dim rownum as integer
dim colnum as integer
dim lstrow as integer
dim lstcol as integer
dim r as range

'finds the last row

lastrow = ActiveSheet.UsedRange.Rows.Count

'finds the last column

lastcol = ActiveSheet.UsedRange.Columns.Count

'sets the range

set r = range(cells(rownum,colnum), cells(lstrow,lstcol))

Insert auto increment primary key to existing table

In order to make the existing primary key as auto_increment, you may use:


Is there an auto increment in sqlite?

I know this answer is a bit late.
My purpose for this answer is for everyone's reference should they encounter this type of challenge with SQLite now or in the future and they're having a hard time with it.

Now, looking back at your query, it should be something like this.

CREATE TABLE people (id integer primary key autoincrement, first_name varchar(20), last_name varchar(20));

It works on my end. Like so,

enter image description here

Just in case you are working with SQLite, I suggest for you to check out DB Browser for SQLite. Works on different platforms as well.

Failed to load JavaHL Library

My Understanding - Basically, svn client comes by default on Mac os. While installing in eclipse we should match svn plugin to the mac plugin and javaHL wont be missing. There is a lengthy process to update by installing xcode and then by using homebrew or macports which you can find after googling but if you are in hurry use simply the steps below.

1) on your mac terminal shell

$ svn --version

Note down the version e.g. 1.7.

2) open the link below

check which version of subclipse you need corresponding to it. e.g.

Subclipse Version SVN/JavaHL Version 1.8.x 1.7.x

3) ok, pick up url corresponding to 1.8.x from

and add to your eclipse => Install new Software under help

select whatever you need, svn client or subclipse or mylyn etc and it will ask for restart of STS/eclipse thats it you are done. worked for me.

NOTE: if you already have multiple versions installed inside your eclipse then its best to uninstall all subclipse or svn client versions from eclipse plugins and start fresh with steps listed above.

How do I divide so I get a decimal value?

Don't worry about it. In your code, just do the separate / and % operations as you mention, even though it might seem like it's inefficient. Let the JIT compiler worry about combining these operations to get both quotient and remainder in a single machine instruction (as far as I recall, it generally does).

SmtpException: Unable to read data from the transport connection: net_io_connectionclosed

In my case, the customer forgot to add new IP address in their SMTP settings. Open IIS 6.0 in the server which sets up the smtp, right click Smtp virtual server, choose Properties, Access tab, click Connections, add IP address of the new server. Then click Relay, also add IP address of the new server. This solved my issue.

get launchable activity name of package from adb

You can also use ddms for logcat logs where just giving search of the app name you will all info but you have to select Info instead of verbose or other options. check this below image.

enter image description here

Difference between OpenJDK and Adoptium/AdoptOpenJDK

Update: AdoptOpenJDK has changed its name to Adoptium, as part of its move to the Eclipse Foundation.

OpenJDK ? source code
Adoptium/AdoptOpenJDK ? builds

Difference between OpenJDK and AdoptOpenJDK

The first provides source-code, the other provides builds of that source-code.

Several vendors of Java & OpenJDK

Adoptium of the Eclipse Foundation, formerly known as AdoptOpenJDK, is only one of several vendors distributing implementations of the Java platform. These include:

  • Eclipse Foundation (Adoptium/AdoptOpenJDK)
  • Azul Systems
  • Oracle
  • Red Hat / IBM
  • BellSoft
  • SAP
  • Amazon AWS
  • … and more

See this flowchart of mine to help guide you in picking a vendor for an implementation of the Java platform. Click/tap to zoom.

Flowchart guiding you in choosing a vendor for a Java 11 implementation

Another resource: This comparison matrix by Azul Systems is useful, and seems true and fair to my mind.

Here is a list of considerations and motivations to consider in choosing a vendor and implementation.

Motivations in choosing a vendor for Java

Some vendors offer you a choice of JIT technologies.

Diagram showing history of HotSpot & JRockit merging, and OpenJ9 both available in AdoptOpenJDK

To understand more about this Java ecosystem, read Java Is Still Free

How to get the current date and time

Just construct a new Date object without any arguments; this will assign the current date and time to the new object.

import java.util.Date;

Date d = new Date();

In the words of the Javadocs for the zero-argument constructor:

Allocates a Date object and initializes it so that it represents the time at which it was allocated, measured to the nearest millisecond.

Make sure you're using java.util.Date and not java.sql.Date -- the latter doesn't have a zero-arg constructor, and has somewhat different semantics that are the topic of an entirely different conversation. :)

How to add option to select list in jQuery


How to add a filter class in Spring Boot?

This filter will also help you to allow cross origin access

public class SimpleCORSFilter implements Filter {

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {

            HttpServletResponse response = (HttpServletResponse) res;
            HttpServletRequest request = (HttpServletRequest) req;
            response.setHeader("Access-Control-Allow-Origin", "*");
            response.setHeader("Access-Control-Allow-Methods", "POST, GET, OPTIONS, DELETE");
            response.setHeader("Access-Control-Max-Age", "20000");
            response.setHeader("Access-Control-Allow-Headers", "x-requested-with, authorization, Content-Type, Authorization, credential, X-XSRF-TOKEN");

            if("OPTIONS".equalsIgnoreCase(request.getMethod())) {
            } else {
                chain.doFilter(req, res);

    public void destroy() {}

    public void init(FilterConfig arg0) throws ServletException {
        // TODO Auto-generated method stub



How to right-align form input boxes?

To affect ONLY text type input boxes use the attribute selector


This way it will not affect other inputs and just text inputs.

example, use a div and give it an idea to refer to:

#divEntry input[type="text"] {
text-align: right;}

How to get resources directory path programmatically

Just use class. Example:

 URL url = Resources.getResource("file name")

After that you have methods like: .getContent(), .getFile(), .getPath() etc

Implement division with bit-wise operator

This solution works perfectly.

#include <stdio.h>

int division(int dividend, int divisor, int origdiv, int * remainder)
    int quotient = 1;

    if (dividend == divisor)
        *remainder = 0;
        return 1;

    else if (dividend < divisor)
        *remainder = dividend;
        return 0;

    while (divisor <= dividend)
        divisor = divisor << 1;
        quotient = quotient << 1;

    if (dividend < divisor)
        divisor >>= 1;
        quotient >>= 1;

    quotient = quotient + division(dividend - divisor, origdiv, origdiv, remainder);

    return quotient;

int main()
    int n = 377;
    int d = 7;
    int rem = 0;

    printf("Quotient : %d\n", division(n, d, d, &rem));
    printf("Remainder: %d\n", rem);

    return 0;

Trying to mock, but not working

Generally speaking, you would have datetime or perhaps imported into a module somewhere. A more effective way of mocking the method would be to patch it on the module that is importing it. Example:

from datetime import date

def my_method():

Then for your test, the mock object itself would be passed as an argument to the test method. You would set up the mock with the result value you want, and then call your method under test. Then you would assert that your method did what you want.

>>> import mock
>>> import a
>>> @mock.patch('')
... def test_my_method(date_mock):
... =
...     result = a.my_method()
...     print result
...     assert == result
>>> test_my_method()

A word of warning. It is most certainly possible to go overboard with mocking. When you do, it makes your tests longer, harder to understand, and impossible to maintain. Before you mock a method as simple as, ask yourself if you really need to mock it. If your test is short and to the point and works fine without mocking the function, you may just be looking at an internal detail of the code you're testing rather than an object you need to mock.

How to delete history of last 10 commands in shell?

Combining answers from above:

history -w vi ~/.bash_history history -r

How to save a list to a file and read it as a list type?

I decided I didn't want to use a pickle because I wanted to be able to open the text file and change its contents easily during testing. Therefore, I did this:

score = [1,2,3,4,5]

with open("file.txt", "w") as f:
    for s in score:
        f.write(str(s) +"\n")
score = []
with open("file.txt", "r") as f:
  for line in f:

So the items in the file are read as integers, despite being stored to the file as strings.

How can I declare a two dimensional string array?

A 3x3 (multidimensional) array can also be initialized (you have already declared it) like this:

string[,] Tablero =  {
                        { "a", "b", "c" },
                        { "d", "e", "f" }, 
                        { "g", "h", "i"} 

Convert date from String to Date format in Dataframes

Since your main aim was to convert the type of a column in a DataFrame from String to Timestamp, I think this approach would be better.

import org.apache.spark.sql.functions.{to_date, to_timestamp}
val modifiedDF = DF.withColumn("Date", to_date($"Date", "MM/dd/yyyy"))

You could also use to_timestamp (I think this is available from Spark 2.x) if you require fine grained timestamp.

Check file size before upload

I created a jQuery version of PhpMyCoder's answer:

$('form').submit(function( e ) {    
    if(!($('#file')[0].files[0].size < 10485760 && get_extension($('#file').val()) == 'jpg')) { // 10 MB (this size is in bytes)
        //Prevent default and display error
        alert("File is wrong type or over 10Mb in size!");

function get_extension(filename) {
    return filename.split('.').pop().toLowerCase();

Stop a gif animation onload, on mouseover start the activation

There is only one way from what I am aware.

Have 2 images, first a jpeg with first frame(or whatever you want) of the gif and the actual gif.

Load the page with the jpeg in place and on mouse over replace the jpeg with the gif. You can preload the gifs if you want or if they are of big size show a loading while the gif is loading and then replace the jpeg with it.

If you whant it to bi linear as in have the gif play on mouse over, stop it on mouse out and then resume play from the frame you stopped, then this cannot be done with javascript+gif combo.

What is the yield keyword used for in C#?

Here is a simple way to understand the concept: The basic idea is, if you want a collection that you can use "foreach" on, but gathering the items into the collection is expensive for some reason (like querying them out of a database), AND you will often not need the entire collection, then you create a function that builds the collection one item at a time and yields it back to the consumer (who can then terminate the collection effort early).

Think of it this way: You go to the meat counter and want to buy a pound of sliced ham. The butcher takes a 10-pound ham to the back, puts it on the slicer machine, slices the whole thing, then brings the pile of slices back to you and measures out a pound of it. (OLD way). With yield, the butcher brings the slicer machine to the counter, and starts slicing and "yielding" each slice onto the scale until it measures 1-pound, then wraps it for you and you're done. The Old Way may be better for the butcher (lets him organize his machinery the way he likes), but the New Way is clearly more efficient in most cases for the consumer.

How to exclude particular class name in CSS selector?

In modern browsers you can do:


Consult for compatibility information.