Programs & Examples On #Createcriteria

No found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations:

In my case, I had the following structure of a project:

enter image description here

When I was running the test, I kept receiving problems with auro-wiring both facade and kafka attributes - error came back with information about missing instances, even though the test and the API classes reside in the very same package. Apparently those were not scanned.

What actually helped was adding @Import annotation bringing the missing classes to Spring classpath and making them being instantiated.

org.hibernate.QueryException: could not resolve property: filename

Hibernate queries are case sensitive with property names (because they end up relying on getter/setter methods on the @Entity).

Make sure you refer to the property as fileName in the Criteria query, not filename.

Specifically, Hibernate will call the getter method of the filename property when executing that Criteria query, so it will look for a method called getFilename(). But the property is called FileName and the getter getFileName().

So, change the projection like so:


Hibernate Criteria Join with 3 Tables

The fetch mode only says that the association must be fetched. If you want to add restrictions on an associated entity, you must create an alias, or a subcriteria. I generally prefer using aliases, but YMMV:

Criteria c = session.createCriteria(Dokument.class, "dokument");
c.createAlias("dokument.role", "role"); // inner join by default
c.createAlias("", "contact");
c.add(Restrictions.eq("contact.lastName", "Test"));
return c.list();

This is of course well explained in the Hibernate reference manual, and the javadoc for Criteria even has examples. Read the documentation: it has plenty of useful information.

Hibernate Criteria for Dates

try this,

    String dateStr = "17-April-2011 19:20:23.707000000 ";
    Date dateForm = new SimpleDateFormat("dd-MMMM-yyyy HH:mm:ss").parse(dateStr);
    SimpleDateFormat format = new SimpleDateFormat("dd-MM-yyyy");  

    String newDate = format.format(dateForm);  

    Calendar today = Calendar.getInstance();
    Date fromDate = format.parse(newDate);
    today.add(Calendar.DAY_OF_YEAR, 1);
    Date toDate= new SimpleDateFormat("dd-MM-yyyy").parse(format.format(today.getTime()));

    Criteria crit = sessionFactory.getCurrentSession().createCriteria(Model.class);
    crit.add("dateFieldName", fromDate));
    crit.add(Restrictions.le("dateFieldName", toDate));
    return crit.list();

failed to lazily initialize a collection of role

Try swich fetchType from LAZY to EAGER

private Set<NodeValue> nodeValues;

But in this case your app will fetch data from DB anyway. If this query very hard - this may impact on performance. More here:

==> 73

No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here

You can have the @Transactional in the child class, but you have to override each of the methods and call the super method in order to get it to work.


@Transactional(readOnly = true)
public class Bob<SomeClass> {
   public SomeClass getValue() {
       return super.getValue();

This allows it to set it up for each of the methods it's needed for.

ORDER BY using Criteria API

For Hibernate 5.2 and above, use CriteriaBuilder as follows

CriteriaBuilder builder = sessionFactory.getCriteriaBuilder();
CriteriaQuery<Cat> query = builder.createQuery(Cat.class);
Root<Cat> rootCat = query.from(Cat.class);
Join<Cat,Mother> joinMother = rootCat.join("mother");  // <-attribute name
Join<Mother,Kind> joinMotherKind = joinMother.join("kind");"value")));
Query<Cat> q = sessionFactory.getCurrentSession().createQuery(query);
List<Cat> cats = q.getResultList();

How to get SQL from Hibernate Criteria API (*not* for logging)

Here's "another" way to get the SQL :

CriteriaImpl criteriaImpl = (CriteriaImpl)criteria;
SessionImplementor session = criteriaImpl.getSession();
SessionFactoryImplementor factory = session.getFactory();
CriteriaQueryTranslator translator=new CriteriaQueryTranslator(factory,criteriaImpl,criteriaImpl.getEntityOrClassName(),CriteriaQueryTranslator.ROOT_SQL_ALIAS);
String[] implementors = factory.getImplementors( criteriaImpl.getEntityOrClassName() );

CriteriaJoinWalker walker = new CriteriaJoinWalker((OuterJoinLoadable)factory.getEntityPersister(implementors[0]), 
                        session.getLoadQueryInfluencers()   );

String sql=walker.getSQLString();

Hibernate Query By Example and Projections

I do not really think so, what I can find is the word "this." causes the hibernate not to include any restrictions in its query, which means it got all the records lists. About the hibernate bug that was reported, I can see it's reported as fixed but I totally failed to download the Patch.

How can I use NSError in my iPhone App?

I would like to add some more suggestions based on my most recent implementation. I've looked at some code from Apple and I think my code behaves in much the same way.

The posts above already explain how to create NSError objects and return them, so I won't bother with that part. I'll just try to suggest a good way to integrate errors (codes, messages) in your own app.

I recommend creating 1 header that will be an overview of all the errors of your domain (i.e. app, library, etc..). My current header looks like this:


FOUNDATION_EXPORT NSString *const FSMyAppErrorDomain;

enum {
    FSUserNotLoggedInError = 1000,


#import "FSError.h" 

NSString *const FSMyAppErrorDomain = @"com.felis.myapp";

Now when using the above values for errors, Apple will create some basic standard error message for your app. An error could be created like the following:

+ (FSProfileInfo *)profileInfoWithData:(NSData *)data error:(NSError **)error
    FSProfileInfo *profileInfo = [[FSProfileInfo alloc] init];
    if (profileInfo)
        /* ... lots of parsing code here ... */

        if (profileInfo.username == nil)
            *error = [NSError errorWithDomain:FSMyAppErrorDomain code:FSProfileParsingFailedError userInfo:nil];            
            return nil;
    return profileInfo;

The standard Apple-generated error message (error.localizedDescription) for the above code will look like the following:

Error Domain=com.felis.myapp Code=1002 "The operation couldn’t be completed. (com.felis.myapp error 1002.)"

The above is already quite helpful for a developer, since the message displays the domain where the error occured and the corresponding error code. End users will have no clue what error code 1002 means though, so now we need to implement some nice messages for each code.

For the error messages we have to keep localisation in mind (even if we don't implement localized messages right away). I've used the following approach in my current project:

1) create a strings file that will contain the errors. Strings files are easily localizable. The file could look like the following:


"1000" = "User not logged in.";
"1001" = "Logout failed.";
"1002" = "Parser failed.";
"1003" = "Incorrect username or password.";
"1004" = "Failed to parse FNID."

2) Add macros to convert integer codes to localized error messages. I've used 2 macros in my Constants+Macros.h file. I always include this file in the prefix header (MyApp-Prefix.pch) for convenience.


// error handling ...

#define FS_ERROR_KEY(code)                    [NSString stringWithFormat:@"%d", code]
#define FS_ERROR_LOCALIZED_DESCRIPTION(code)  NSLocalizedStringFromTable(FS_ERROR_KEY(code), @"FSError", nil)

3) Now it's easy to show a user friendly error message based on an error code. An example:

UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" 
[alert show];

Equivalent of SQL ISNULL in LINQ?

Since aa is the set/object that might be null, can you check aa == null ?

(aa / xx might be interchangeable (a typo in the question); the original question talks about xx but only defines aa)


select new {
    AssetID = x.AssetID,
    Status = aa == null ? (bool?)null : aa.Online; // a Nullable<bool>

or if you want the default to be false (not null):

select new {
    AssetID = x.AssetID,
    Status = aa == null ? false : aa.Online;

Update; in response to the downvote, I've investigated more... the fact is, this is the right approach! Here's an example on Northwind:

        using(var ctx = new DataClasses1DataContext())
            ctx.Log = Console.Out;
            var qry = from boss in ctx.Employees
                      join grunt in ctx.Employees
                          on boss.EmployeeID equals grunt.ReportsTo into tree
                      from tmp in tree.DefaultIfEmpty()
                      select new
                                 ID = boss.EmployeeID,
                                 Name = tmp == null ? "" : tmp.FirstName
            foreach(var row in qry)
                Console.WriteLine("{0}: {1}", row.ID, row.Name);

And here's the TSQL - pretty much what we want (it isn't ISNULL, but it is close enough):

SELECT [t0].[EmployeeID] AS [ID],
        WHEN [t2].[test] IS NULL THEN CONVERT(NVarChar(10),@p0)
        ELSE [t2].[FirstName]
     END) AS [Name]
FROM [dbo].[Employees] AS [t0]
    SELECT 1 AS [test], [t1].[FirstName], [t1].[ReportsTo]
    FROM [dbo].[Employees] AS [t1]
    ) AS [t2] ON ([t0].[EmployeeID]) = [t2].[ReportsTo]
-- @p0: Input NVarChar (Size = 0; Prec = 0; Scale = 0) []
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 3.5.30729.1


Best /Fastest way to read an Excel Sheet into a DataTable?

I have always used OLEDB for this, something like...

    Dim sSheetName As String
    Dim sConnection As String
    Dim dtTablesList As DataTable
    Dim oleExcelCommand As OleDbCommand
    Dim oleExcelReader As OleDbDataReader
    Dim oleExcelConnection As OleDbConnection

    sConnection = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Test.xls;Extended Properties=""Excel 12.0;HDR=No;IMEX=1"""

    oleExcelConnection = New OleDbConnection(sConnection)

    dtTablesList = oleExcelConnection.GetSchema("Tables")

    If dtTablesList.Rows.Count > 0 Then
        sSheetName = dtTablesList.Rows(0)("TABLE_NAME").ToString
    End If


    If sSheetName <> "" Then

        oleExcelCommand = oleExcelConnection.CreateCommand()
        oleExcelCommand.CommandText = "Select * From [" & sSheetName & "]"
        oleExcelCommand.CommandType = CommandType.Text

        oleExcelReader = oleExcelCommand.ExecuteReader

        nOutputRow = 0

        While oleExcelReader.Read

        End While


    End If


The ACE.OLEDB provider will read both .xls and .xlsx files and I have always found the speed quite good.

How can I concatenate two arrays in Java?

In Haskell you can do something like that [a, b, c] ++ [d, e] to get [a, b, c, d, e]. These are Haskell lists concatenated but that'd very nice to see a similar operator in Java for arrays. Don't you think so ? That's elegant, simple, generic and it's not that difficult to implement.

If you want to, I suggest you to have a look at Alexander Hristov's work in his Hacking the OpenJDK compiler. He explains how to modify javac source to create a new operator. His example consists in defining a '**' operator where i ** j = Math.pow(i, j). One could take that example to implement an operator that concatenates two arrays of same type.

Once you do that, you are bound to your customized javac to compile your code but the generated bytecode will be understood by any JVM.

Of course, you can implement your own array concatenatation method at your source level, there are many examples on how to do it in the other answers !

There are so many useful operators that could be added, this one would be one of them.

How do I put the image on the right side of the text in a UIButton?

Swift 4 & 5

Change the direction of UIButton image (RTL and LTR)

extension UIButton {
    func changeDirection(){
       isArabic ? (self.contentHorizontalAlignment = .right) : (self.contentHorizontalAlignment = .left)
        // left-right margin 
        self.imageEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
        self.titleEdgeInsets = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)

Class type check in TypeScript

You can use the instanceof operator for this. From MDN:

The instanceof operator tests whether the prototype property of a constructor appears anywhere in the prototype chain of an object.

If you don't know what prototypes and prototype chains are I highly recommend looking it up. Also here is a JS (TS works similar in this respect) example which might clarify the concept:

    class Animal {_x000D_
        constructor(name) {_x000D_
   = name;_x000D_
    const animal = new Animal('fluffy');_x000D_
    // true because Animal in on the prototype chain of animal_x000D_
    console.log(animal instanceof Animal); // true_x000D_
    // Proof that Animal is on the prototype chain_x000D_
    console.log(Object.getPrototypeOf(animal) === Animal.prototype); // true_x000D_
    // true because Object in on the prototype chain of animal_x000D_
    console.log(animal instanceof Object); _x000D_
    // Proof that Object is on the prototype chain_x000D_
    console.log(Object.getPrototypeOf(Animal.prototype) === Object.prototype); // true_x000D_
    console.log(animal instanceof Function); // false, Function not on prototype chain_x000D_

The prototype chain in this example is:

animal > Animal.prototype > Object.prototype

Normalize columns of pandas data frame

Based on this post:

You can do the following:

def normalize(df):
    result = df.copy()
    for feature_name in df.columns:
        max_value = df[feature_name].max()
        min_value = df[feature_name].min()
        result[feature_name] = (df[feature_name] - min_value) / (max_value - min_value)
    return result

You don't need to stay worrying about whether your values are negative or positive. And the values should be nicely spread out between 0 and 1.

System.Runtime.InteropServices.COMException (0x800A03EC)

I was seeing this same error when trying to save an excel file. The code worked fine when I was using MS Office 2003, but after upgrading to MS Office 2007 I started seeing this. It would happen anytime I tried to save an Excel file to a server or remote fie share.

My solution, though rudimentary, worked well. I just had the program save the file locally, like to the user's C:\ drive. Then use the "System.IO.File.Copy(File, Destination, Overwrite)" method to move the file to the server. Then you can delete the file on the C:\ drive.

Works great, and simple. But admittedly not the most elegant approach.

Hope this helps! I was having a ton of trouble finding any solutions on the web till this idea popped into my head.

Asp.Net WebApi2 Enable CORS not working with AspNet.WebApi.Cors 5.2.3

In case of CORS request all modern browsers respond with an OPTION verb, and then the actual request follows through. This is supposed to be used to prompt the user for confirmation in case of a CORS request. But in case of an API if you would want to skip this verification process add the following snippet to Global.asax

        protected void Application_BeginRequest(object sender, EventArgs e)
            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "*");
            if (HttpContext.Current.Request.HttpMethod == "OPTIONS")
                HttpContext.Current.Response.AddHeader("Access-Control-Allow-Methods", "POST, PUT, DELETE");

                HttpContext.Current.Response.AddHeader("Access-Control-Allow-Headers", "Content-Type, Accept");
                HttpContext.Current.Response.AddHeader("Access-Control-Max-Age", "1728000");

Here we are just by passing the check by checking for OPTIONS verb.

Truncate a SQLite table if it exists?

SELECT name FROM sqlite_master where name = '<TABLE_NAME_HERE>'

If the table name does not exist then there would not be any records returned!

You can as well use

SELECT count(name) FROM sqlite_master where name = '<TABLE_NAME_HERE>' 

if the count is 1, means table exists, otherwise, it would return 0

Iterate over a Javascript associative array in sorted order

You cannot iterate over them directly, but you can find all the keys and then just sort them.

var a = new Array();
a['b'] = 1;
a['z'] = 1;
a['a'] = 1;    

function keys(obj)
    var keys = [];

    for(var key in obj)

    return keys;

keys(a).sort(); // ["a", "b", "z"]

However there is no need to make the variable 'a' an array. You are really just using it as an object and should create it like this:

var a = {};
a["key"] = "value";

How to build a 2 Column (Fixed - Fluid) Layout with Twitter Bootstrap?

Update 2018

Bootstrap 4

Now that BS4 is flexbox, the fixed-fluid is simple. Just set the width of the fixed column, and use the .col class on the fluid column.

.sidebar {
    width: 180px;
    min-height: 100vh;

<div class="row">
    <div class="sidebar p-2">Fixed width</div>
    <div class="col bg-dark text-white pt-2">

Bootstrap 3..

One approach to a fixed-fluid layout is using media queries that align with Bootstrap's breakpoints so that you only use the fixed width columns are larger screens and then let the layout stack responsively on smaller screens...

@media (min-width:768px) {
  #sidebar {
      min-width: 300px;
      max-width: 300px;
  #main {
      width:calc(100% - 300px);

Working Bootstrap 3 Fixed-Fluid Demo

Related Q&A:
Fixed width column with a container-fluid in bootstrap
How to left column fixed and right scrollable in Bootstrap 4, responsive?

Filtering a list based on a list of booleans

With python 3 you can use list_a[filter] to get True values. To get False values use list_a[~filter]

set height of imageview as matchparent programmatically

You can use the MATCH_PARENT constant or its numeric value -1.

How to programmatically click a button in WPF?

if you want to call click event:

SomeButton.RaiseEvent(new RoutedEventArgs(Button.ClickEvent));

And if you want the button looks like it is pressed:

typeof(Button).GetMethod("set_IsPressed", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(SomeButton, new object[] { true });

and unpressed after that:

typeof(Button).GetMethod("set_IsPressed", BindingFlags.Instance | BindingFlags.NonPublic).Invoke(SomeButton, new object[] { false });

or use the ToggleButton

What is the purpose of the "final" keyword in C++11 for functions?

Final cannot be applied to non-virtual functions.

error: only virtual member functions can be marked 'final'

It wouldn't be very meaningful to be able to mark a non-virtual method as 'final'. Given

struct A { void foo(); };
struct B : public A { void foo(); };
A * a = new B;
a -> foo(); // this will call A :: foo anyway, regardless of whether there is a B::foo

a->foo() will always call A::foo.

But, if A::foo was virtual, then B::foo would override it. This might be undesirable, and hence it would make sense to make the virtual function final.

The question is though, why allow final on virtual functions. If you have a deep hierarchy:

struct A            { virtual void foo(); };
struct B : public A { virtual void foo(); };
struct C : public B { virtual void foo() final; };
struct D : public C { /* cannot override foo */ };

Then the final puts a 'floor' on how much overriding can be done. Other classes can extend A and B and override their foo, but it a class extends C then it is not allowed.

So it probably doesn't make sense to make the 'top-level' foo final, but it might make sense lower down.

(I think though, there is room to extend the words final and override to non-virtual members. They would have a different meaning though.)

send mail to multiple receiver with HTML mailto

"There are no safe means of assigning multiple recipients to a single mailto: link via HTML. There are safe, non-HTML, ways of assigning multiple recipients from a mailto: link."

For a quick fix to your problem, change your ; to a comma , and eliminate the spaces between email addresses

<a href='mailto:[email protected],[email protected]'>Email Us</a>

"git rebase origin" vs."git rebase origin/master"

You can make a new file under [.git\refs\remotes\origin] with name "HEAD" and put content "ref: refs/remotes/origin/master" to it. This should solve your problem.

It seems that clone from an empty repos will lead to this. Maybe the empty repos do not have HEAD because no commit object exist.

You can use the

git log --remotes --branches --oneline --decorate

to see the difference between each repository, while the "problem" one do not have "origin/HEAD"

Edit: Give a way using command line
You can also use git command line to do this, they have the same result

git symbolic-ref refs/remotes/origin/HEAD refs/remotes/origin/master

Why is list initialization (using curly braces) better than the alternatives?

Basically copying and pasting from Bjarne Stroustrup's "The C++ Programming Language 4th Edition":

List initialization does not allow narrowing (§iso.8.5.4). That is:

  • An integer cannot be converted to another integer that cannot hold its value. For example, char to int is allowed, but not int to char.
  • A floating-point value cannot be converted to another floating-point type that cannot hold its value. For example, float to double is allowed, but not double to float.
  • A floating-point value cannot be converted to an integer type.
  • An integer value cannot be converted to a floating-point type.


void fun(double val, int val2) {

    int x2 = val;    // if val == 7.9, x2 becomes 7 (bad)

    char c2 = val2;  // if val2 == 1025, c2 becomes 1 (bad)

    int x3 {val};    // error: possible truncation (good)

    char c3 {val2};  // error: possible narrowing (good)

    char c4 {24};    // OK: 24 can be represented exactly as a char (good)

    char c5 {264};   // error (assuming 8-bit chars): 264 cannot be 
                     // represented as a char (good)

    int x4 {2.0};    // error: no double to int value conversion (good)


The only situation where = is preferred over {} is when using auto keyword to get the type determined by the initializer.


auto z1 {99};   // z1 is an int
auto z2 = {99}; // z2 is std::initializer_list<int>
auto z3 = 99;   // z3 is an int


Prefer {} initialization over alternatives unless you have a strong reason not to.

Flattening a shallow list in Python

The easiest way to achieve this in either Python 2 or 3 is to use the morph library using pip install morph.

The code is:

import morph

list = [[1,2],[3],[5,89],[],[6]]
flattened_list = morph.flatten(list)  # returns [1, 2, 3, 5, 89, 6]

Format a datetime into a string with milliseconds

from datetime import datetime
from time import clock

t = datetime.utcnow()
print 't == %s    %s\n\n' % (t,type(t))

n = 100000

te = clock()
for i in xrange(1):
    t_stripped = t.strftime('%Y%m%d%H%M%S%f')
print clock()-te
print t_stripped," t.strftime('%Y%m%d%H%M%S%f')"


te = clock()
for i in xrange(1):
    t_stripped = str(t).replace('-','').replace(':','').replace('.','').replace(' ','')
print clock()-te
print t_stripped," str(t).replace('-','').replace(':','').replace('.','').replace(' ','')"


te = clock()
for i in xrange(n):
    t_stripped = str(t).translate(None,' -:.')
print clock()-te
print t_stripped," str(t).translate(None,' -:.')"


te = clock()
for i in xrange(n):
    s = str(t)
    t_stripped = s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:] 
print clock()-te
print t_stripped," s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:] "


t == 2011-09-28 21:31:45.562000    <type 'datetime.datetime'>

20110928212155046000  t.strftime('%Y%m%d%H%M%S%f')

20110928212130453000 str(t).replace('-','').replace(':','').replace('.','').replace(' ','')

20110928212130453000 str(t).translate(None,' -:.')

20110928212130453000 s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]

Use of translate() and slicing method run in same time
translate() presents the advantage to be usable in one line

Comparing the times on the basis of the first one:

1.000 * t.strftime('%Y%m%d%H%M%S%f')

0.351 * str(t).replace('-','').replace(':','').replace('.','').replace(' ','')

0.198 * str(t).translate(None,' -:.')

0.194 * s[:4] + s[5:7] + s[8:10] + s[11:13] + s[14:16] + s[17:19] + s[20:]

TensorFlow not found using pip

  1. Install python by checking Add Python to Path
  2. pip3 install --upgrade

This works for windows 10.0

What is the difference between the dot (.) operator and -> in C++?

The target. dot works on objects; arrow works on pointers to objects.

std::string str("foo");
std::string * pstr = new std::string("foo");

str.size ();
pstr->size ();

How can I get the count of milliseconds since midnight for the current?


You ask for the fraction of a second of the current time as a number of milliseconds (not count from epoch).                               // Get current moment in UTC, then…
       .get( ChronoField.MILLI_OF_SECOND )  // interrogate a `TemporalField`.

2017-04-25T03:01:14.113Z ? 113

  1. Get the fractional second in nanoseconds (billions).
  2. Divide by a thousand to truncate to milliseconds (thousands).

See this code run live at

Using java.time

The modern way is with the java.time classes.

Capture the current moment in UTC.

Use the Instant.get method to interrogate for the value of a TemporalField. In our case, the TemporalField we want is ChronoField.MILLI_OF_SECOND.

int millis = ChronoField.MILLI_OF_SECOND ) ;  // Get current moment in UTC, then interrogate a `TemporalField`.

Or do the math yourself.

More likely you are asking this for a specific time zone. The fraction of a second is likely to be the same as with Instant but there are so many anomalies with time zones, I hesitate to make that assumption.

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

Interrogate for the fractional second. The Question asked for milliseconds, but java.time classes use a finer resolution of nanoseconds. That means the number of nanoseconds will range from from 0 to 999,999,999.

long nanosFractionOfSecond = zdt.getNano();

If you truly want milliseconds, truncate the finer data by dividing by one million. For example, a half second is 500,000,000 nanoseconds and also is 500 milliseconds.

long millis = ( nanosFractionOfSecond / 1_000_000L ) ;  // Truncate nanoseconds to milliseconds, by a factor of one million.

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.

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.

HREF="" automatically adds to current page URL (in PHP). Can't figure it out

if you want to redirect it to some other url lets then make your like as happy to help other says rikin <a href="//">happy to help other says rikin</a> this will remove self site url form the href.

Eclipse error "ADB server didn't ACK, failed to start daemon"

ADB will often fail if there is a newline in adb_usb.ini. Remove it, restart it, and that will often solve the problem (at least for me anyway).

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

I've got another simple solution:


<a href="#alert" class="span3" tabindex="0">Hide Me</a>
<a href="#" class="span2" tabindex="0">Show Me</a>
<p id="alert" class="alert" >Some alarming information here</p>


body { display: block; }
p.alert:target { display: none; }


Pandas: sum DataFrame rows for given columns

You can simply pass your dataframe into the following function:

def sum_frame_by_column(frame, new_col_name, list_of_cols_to_sum):
    frame[new_col_name] = frame[list_of_cols_to_sum].astype(float).sum(axis=1)


I have a dataframe (awards_frame) as follows:

enter image description here

...and I want to create a new column that shows the sum of awards for each row:


I simply pass my awards_frame into the function, also specifying the name of the new column, and a list of column names that are to be summed:

sum_frame_by_column(awards_frame, 'award_sum', ['award_1','award_2','award_3'])


enter image description here

Zoom to fit: PDF Embedded in HTML

Bit late response to this question, however I do have something to add that might be useful for others.

If you make use of an iFrame and set the pdf file path to the src, it will load zoomed out to 100%, which the equivalence of FitH

how to make a html iframe 100% width and height?

this code probable help you .

<iframe src="" onload="this.width=screen.width;this.height=screen.height;">

Calculating frames per second in a game

store a start time and increment your framecounter once per loop? every few seconds you could just print framecount/(Now - starttime) and then reinitialize them.

edit: oops. double-ninja'ed

How to Import .bson file format on mongodb

Run the following from command line and you should be in the Mongo bin directory.

mongorestore -d db_name -c collection_name path/file.bson

How do I check if an integer is even or odd?

Use bit arithmetic:

if((x & 1) == 0)

This is faster than using division or modulus.

Creating composite primary key in SQL Server

If you use management studio, simply select the wardNo, BHTNo, testID columns and click on the key mark in the toolbar.

enter image description here

Command for this is,

ALTER TABLE dbo.testRequest

Comparing boxed Long values 127 and 128

Comparing non-primitives (aka Objects) in Java with == compares their reference instead of their values. Long is a class and thus Long values are Objects.

The problem is that the Java Developers wanted people to use Long like they used long to provide compatibility, which led to the concept of autoboxing, which is essentially the feature, that long-values will be changed to Long-Objects and vice versa as needed. The behaviour of autoboxing is not exactly predictable all the time though, as it is not completely specified.

So to be safe and to have predictable results always use .equals() to compare objects and do not rely on autoboxing in this case:

Long num1 = 127, num2 = 127;
if(num1.equals(num2)) { iWillBeExecutedAlways(); }

Python Dictionary Comprehension

I really like the @mgilson comment, since if you have a two iterables, one that corresponds to the keys and the other the values, you can also do the following.

keys = ['a', 'b', 'c']
values = [1, 2, 3]
d = dict(zip(keys, values))


d = {'a': 1, 'b': 2, 'c': 3}

Open directory dialog

You could use smth like this in WPF. I've created example method. Check below.

public string getFolderPath()
           // Create OpenFileDialog 
           Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();

           OpenFileDialog openFileDialog = new OpenFileDialog();
           openFileDialog.Multiselect = false;

           openFileDialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
           if (openFileDialog.ShowDialog() == true)
               System.IO.FileInfo fInfo = new System.IO.FileInfo(openFileDialog.FileName);
               return fInfo.DirectoryName;
           return null;           

How can I add items to an empty set in python

D = {} is a dictionary not set.

>>> d = {}
>>> type(d)
<type 'dict'>

Use D = set():

>>> d = set()
>>> type(d)
<type 'set'>
>>> d.update({1})
>>> d.add(2)
>>> d.update([3,3,3])
>>> d
set([1, 2, 3])

Is there an arraylist in Javascript?

just use array.push();

var array = [];


This will add another item to it.

To take one off, use array.pop();

Link to JavaScript arrays:

Loop code for each file in a directory

Check out the DirectoryIterator class.

From one of the comments on that page:

// output all files and directories except for '.' and '..'
foreach (new DirectoryIterator('../moodle') as $fileInfo) {
    if($fileInfo->isDot()) continue;
    echo $fileInfo->getFilename() . "<br>\n";

The recursive version is RecursiveDirectoryIterator.

get dictionary key by value

I have very simple way to do this. It worked out perfect for me.

Dictionary<string, string> types = new Dictionary<string, string>();

types.Add("1", "one");
types.Add("2", "two");
types.Add("3", "three");

Console.WriteLine("Please type a key to show its value: ");
string rLine = Console.ReadLine();

    string value_For_Key = types[rLine];
    Console.WriteLine("Value for " + rLine + " is" + value_For_Key);

Can an html element have multiple ids?

No. Every DOM element, if it has an id, has a single, unique id. You could approximate it using something like:

<div id='enclosing_id_123'><span id='enclosed_id_123'></span></div>

and then use navigation to get what you really want.

If you are just looking to apply styles, class names are better.

What's the difference between align-content and align-items?

What I have learned from every answer and visiting the blog is

what is the cross axis and main axis

  • main axis is horizontal row and cross axis is vertical column - for flex-direction: row
  • main axis is vertical column and cross axis is horizontal row - for flex-direction: column

Now align-content and align-items

align-content is for the row, it works if the container has (more than one row) Properties of align-content

.container {
  align-content: flex-start | flex-end | center | space-between | space-around | space-evenly | stretch | start | end | baseline | first baseline | last baseline + ... safe | unsafe;

align-items is for the items in row Properties of align-items

.container {
  align-items: stretch | flex-start | flex-end | center | baseline | first baseline | last baseline | start | end | self-start | self-end + ... safe | unsafe;

For more reference visit to flex

Default value in Go's method

No, there is no way to specify defaults. I believer this is done on purpose to enhance readability, at the cost of a little more time (and, hopefully, thought) on the writer's end.

I think the proper approach to having a "default" is to have a new function which supplies that default to the more generic function. Having this, your code becomes clearer on your intent. For example:

func SaySomething(say string) {
    // All the complicated bits involved in saying something

func SayHello() {

With very little effort, I made a function that does a common thing and reused the generic function. You can see this in many libraries, fmt.Println for example just adds a newline to what fmt.Print would otherwise do. When reading someone's code, however, it is clear what they intend to do by the function they call. With default values, I won't know what is supposed to be happening without also going to the function to reference what the default value actually is.

Setting CSS pseudo-class rules from JavaScript

Instead of directly setting pseudo-class rules with javascript, you can set the rules differently in different CSS files, and then use Javascript to switch one stylesheet off and to switch another on. A method is described at A List Apart (qv. for more detail).

Set up the CSS files as,

<link rel="stylesheet" href="always_on.css">
<link rel="stylesheet" title="usual" href="preferred.css"> <!-- on by default -->
<link rel="alternate stylesheet" title="strange" href="alternate.css"> <!-- off by default -->

And then switch between them using javascript:

function setActiveStyleSheet(title) {
   var i, a, main;
   for(i=0; (a = document.getElementsByTagName("link")<i>); i++) {
     if(a.getAttribute("rel").indexOf("style") != -1
        && a.getAttribute("title")) {
       a.disabled = true;
       if(a.getAttribute("title") == title) a.disabled = false;

Use Font Awesome icon as CSS content

a:before {
     content: "\f055";
     font-family: FontAwesome;

Example Link:

Get Icon code from:

Returning http status code from Web Api controller

I hate bumping old articles but this is the first result for this in google search and I had a heck of a time with this problem (even with the support of you guys). So here goes nothing...

Hopefully my solution will help those that also was confused.

namespace MyApplication.WebAPI.Controllers
    public class BaseController : ApiController
        public T SendResponse<T>(T response, HttpStatusCode statusCode = HttpStatusCode.OK)
            if (statusCode != HttpStatusCode.OK)
                // leave it up to microsoft to make this way more complicated than it needs to be
                // seriously i used to be able to just set the status and leave it at that but nooo... now 
                // i need to throw an exception 
                var badResponse =
                    new HttpResponseMessage(statusCode)
                        Content =  new StringContent(JsonConvert.SerializeObject(response), Encoding.UTF8, "application/json")

                throw new HttpResponseException(badResponse);
            return response;

and then just inherit from the BaseController

public class DeviceManagementController : BaseController

and then using it

public SearchForDeviceResponse SearchForDevice(string property, string value)
    //todo: limit search property here?
    var response = new SearchForDeviceResponse();

    var results = _deviceManagementBusiness.SearchForDevices(property, value);

    response.Success = true;
    response.Data = results;

    var statusCode = results == null || !results.Any() ? HttpStatusCode.NoContent : HttpStatusCode.OK;

    return SendResponse(response, statusCode);

How do I check if a list is empty?

len() is an O(1) operation for Python lists, strings, dicts, and sets. Python internally keeps track of the number of elements in these containers.

JavaScript has a similar notion of truthy/falsy.

PHP check if file is an image

The getimagesize() should be the most definite way of working out whether the file is an image:

    $image = true;
} else {
    $image = false;

because this is a sample getimagesize() output:

Array (
[0] => 800
[1] => 450
[2] => 2
[3] => width="800" height="450"
[bits] => 8
[channels] => 3
[mime] => image/jpeg)

Unable to set data attribute using jQuery Data() API

Happened the same to me. It turns out that

var data = $("#myObject").data();

gives you a non-writable object. I solved it using:

var data = $.extend({}, $("#myObject").data());

And from then on, data was a standard, writable JS object.

The type or namespace name 'DbContext' could not be found

Just a quick note. It is DbContext, not DBContext. i.e. with a lowercase 'B'. I discovered this because I had the same problem while intelesense was not working until I tried typing the full name space System.Data.Entity... and name and finally it suggested the lowercase 'b' option:-


Loop through the rows of a particular DataTable

You want to loop on the .Rows, and access the column for the row like q("column")


        For Each q In dtDataTable.Rows
            strDetail = q("Detail")

Also make sure to check msdn doc for any class you are using + use intellisense

Unable to resolve dependency for ':app@debug/compileClasspath': Could not resolve

I'm just sharing this answer because I had similar problem.

In the end, error was caused because I inadvertently changed the fileTree. In my case, I fixed by changing:

// implementation or compile
implementation fileTree(include: ['*.jar'])


// implementation or compile
implementation fileTree(include: ['*.jar'], dir: 'libs')

How to get the name of the current Windows user in JavaScript

JavaScript runs in the context of the current HTML document, so it won't be able to determine anything about a current user unless it's in the current page or you do AJAX calls to a server-side script to get more information.

JavaScript will not be able to determine your Windows user name.

How to check for valid email address?

Email addresses are incredibly complicated. Here's a sample regex that will match every RFC822-valid address:

You'll notice that it's probably longer than the rest of your program. There are even whole modules for Perl with the purpose of validating email addresses. So you probably won't get anything that's 100% perfect as a regex while also being readable. Here's a sample recursive descent parser:

but you'll need to decide whether you need perfect parsing or simple code.

Django - limiting query results

Yes. If you want to fetch a limited subset of objects, you can with the below code:



The beginning 0 is optional, so


The above code returns the first 10 instances.

laravel 5 : Class 'input' not found

'Input' => Illuminate\Support\Facades\Input::class, add it to App.php.

adb shell command to make Android package uninstall dialog appear

I assume that you enable developer mode on your android device and you are connected to your device and you have shell access (adb shell).

Once this is done you can uninstall application with this command pm uninstall --user 0 <>. 0 is root id -this way you don't need too root your device.

Here is an example how I did on my Huawei P110 lite

# gain shell access
$ adb shell

# check who you are
$ whoami

# obtain user id
$ id
uid=2000(shell) gid=2000(shell)

# list packages
$ pm list packages | grep google                                                                                                                                                

# uninstall gmail app
pm uninstall --user 0

What does "all" stand for in a makefile?

The manual for GNU Make gives a clear definition for all in its list of standard targets.

If the author of the Makefile is following that convention then the target all should:

  1. Compile the entire program, but not build documentation.
  2. Be the the default target. As in running just make should do the same as make all.

To achieve 1 all is typically defined as a .PHONY target that depends on the executable(s) that form the entire program:

.PHONY : all
all : executable

To achieve 2 all should either be the first target defined in the make file or be assigned as the default goal:


Remove spacing between table cells and rows

It looks like the DOCTYPE is causing the image to display as an inline element. If I add display: block to the image, problem solved.

Execute another jar in a Java program

.jar isn't executable. Instantiate classes or make call to any static method.

EDIT: Add Main-Class entry while creating a JAR.

> (content of

Main-Class: pk.Test


package pk;
public class Test{
  public static void main(String []args){
    System.out.println("Hello from Test");

Use Process class and it's methods,

public class Exec
   public static void main(String []args) throws Exception
        Process ps=Runtime.getRuntime().exec(new String[]{"java","-jar","A.jar"});
        ps.waitFor(); is=ps.getInputStream();
        byte b[]=new byte[is.available()];,0,b.length);
        System.out.println(new String(b));

Need to list all triggers in SQL Server database with table name and table's schema

Just posting because all solutions so far fall a bit short of completeness.

SELECT AS trigger_table_schema 
    , AS trigger_table_name 
    , AS trigger_name 
    ,sysm.definition AS trigger_definition 

    -- Difference between a FOR and AFTER triggers?
    -- Is the same as
    -- An INSTEAD OF trigger is different, and fires before and instead of the insert 
    -- and can be used on views, in order to insert the appropriate values into the underlying tables.
    -- AFTER specifies that the DML trigger is fired only when all operations 
    -- specified in the triggering SQL statement have executed successfully. 
    -- All referential cascade actions and constraint checks also must succeed before this trigger fires. 
    -- AFTER is the default when FOR is the only keyword specified.
    ,CASE WHEN systrg.is_instead_of_trigger = 1 THEN 0 ELSE 1 END AS is_after_trigger 


    ,CASE WHEN systrg.parent_class = 1 THEN 'TABLE' WHEN systrg.parent_class = 0 THEN 'DATABASE' END trigger_class 

        WHEN systrg.[type] = 'TA' then 'Assembly (CLR) trigger'
        WHEN systrg.[type] = 'TR' then 'SQL trigger' 
        ELSE '' 
    END AS trigger_type 

    -- ,(CASE WHEN objectproperty(systrg.object_id, 'ExecIsUpdateTrigger') = 1
    --      THEN 'UPDATE ' ELSE '' END 
    -- + CASE WHEN objectproperty(systrg.object_id, 'ExecIsDeleteTrigger') = 1
    --      THEN 'DELETE ' ELSE '' END
    -- + CASE WHEN objectproperty(systrg.object_id, 'ExecIsInsertTrigger') = 1
    --      THEN 'INSERT' ELSE '' END
    -- ) AS trigger_event 

                    ', ' + type_desc AS [text()]
                    -- STRING_AGG(type_desc, ', ') AS foo 
                FROM AS syse 
                WHERE syse.object_id = systrg.object_id
                FOR XML PATH(''), TYPE 
                -- GROUP BY syse.object_id 
            ).value('.[1]', 'nvarchar(MAX)') 
            , 1, 2, '' 
    ) AS trigger_event_groups 

    -- ,CASE WHEN systrg.parent_class = 1 THEN 'TABLE' WHEN systrg.parent_class = 0 THEN 'DATABASE' END trigger_class  

    ,'DROP TRIGGER "' + + '"."' + + '"; ' AS sql 
    -- ,systrg.*
FROM sys.triggers AS systrg 

LEFT JOIN sys.sql_modules AS sysm 
    ON sysm.object_id = systrg.object_id 

-- sys.objects for view triggers 
-- LEFT JOIN sys.objects AS systbl ON systbl.object_id = systrg.object_id 

-- inner join if you only want table-triggers 
LEFT JOIN sys.tables AS systbl ON systbl.object_id = systrg.parent_id 

LEFT JOIN sys.schemas AS sch 
    ON sch.schema_id = systbl.schema_id 

WHERE (1=1) 

-- AND = 'dbo' 
-- And here, exclude some triggers with a certain naming schema 
    -- IS NULL 
    -- OR 
    ( = 'TRG_' +  + '_INSERT_History'
        OR = 'TRG_' +  + '_UPDATE_History'
        OR = 'TRG_' +  + '_DELETE_History'


Show "loading" animation on button click

            //do processing
            $(this).attr("label", $(this).text()).text("loading ....").animate({ disabled: true }, 1000, function () {
                //original event call
                $.when($(elm).delay(1000).one("click")).done(function () {//processing finalized
                    $(this).text($(this).attr("label")).animate({ disabled: false }, 1000, function () {

Why does python use 'else' after for and while loops?

The else keyword can be confusing here, and as many people have pointed out, something like nobreak, notbreak is more appropriate.

In order to understand for ... else ... logically, compare it with try...except...else, not if...else..., most of python programmers are familiar with the following code:

    print("Error happened.") # The try block threw an exception
    print("Everything is find.") # The try block does things just find.

Similarly, think of break as a special kind of Exception:

for x in iterable:
except break:
    pass # Implied by Python's loop semantics
    print('no break encountered')  # No break statement was encountered

The difference is python implies except break and you can not write it out, so it becomes:

for x in iterable:
    print('no break encountered')  # No break statement was encountered

Yes, I know this comparison can be difficult and tiresome, but it does clarify the confusion.

angularjs to output plain text instead of html

jQuery is about 40 times SLOWER, please do not use jQuery for that simple task.

function htmlToPlaintext(text) {
  return text ? String(text).replace(/<[^>]+>/gm, '') : '';

usage :

var plain_text = htmlToPlaintext( your_html );

With angular.js :

angular.module('myApp.filters', []).
  filter('htmlToPlaintext', function() {
    return function(text) {
      return  text ? String(text).replace(/<[^>]+>/gm, '') : '';

use :

<div>{{myText | htmlToPlaintext}}</div>  

How do I get the path of the assembly the code is in?

I've been using Assembly.CodeBase instead of Location:

Assembly a;
a = Assembly.GetAssembly(typeof(DaoTests));
string s = a.CodeBase.ToUpper(); // file:///c:/path/name.dll
Assert.AreEqual(true, s.StartsWith("FILE://"), "CodeBase is " + s);
s = s.Substring(7, s.LastIndexOf('/') - 7); // 7 = "file://"
while (s.StartsWith("/")) {
    s = s.Substring(1, s.Length - 1);
s = s.Replace("/", "\\");

It's been working, but I'm no longer sure it is 100% correct. The page at says:

"The CodeBase is a URL to the place where the file was found, while the Location is the path where it was actually loaded. For example, if the assembly was downloaded from the internet, its CodeBase may start with "http://", but its Location may start with "C:\". If the file was shadow-copied, the Location would be the path to the copy of the file in the shadow copy dir. It’s also good to know that the CodeBase is not guaranteed to be set for assemblies in the GAC. Location will always be set for assemblies loaded from disk, however."

You may want to use CodeBase instead of Location.

sys.path different in Jupyter and Python - how to import own modules in Jupyter?

Jupyter has its own PATH variable, JUPYTER_PATH.

Adding this line to the .bashrc file worked for me:

export JUPYTER_PATH=<directory_for_your_module>:$JUPYTER_PATH

How to get correct timestamp in C#

internal static string UnixToDate(int Timestamp, string ConvertFormat)
    DateTime ConvertedUnixTime = DateTimeOffset.FromUnixTimeSeconds(Timestamp).DateTime;
    return ConvertedUnixTime.ToString(ConvertFormat);

int Timestamp = (int)DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1)).TotalSeconds;


UnixToDate(1607013172, "HH:mm:ss"); // Output 16:32:52
Timestamp; // Output 1607013172

Remove element by id


The DOM is organized in a tree of nodes, where each node has a value, along with a list of references to its child nodes. So element.parentNode.removeChild(element) mimics exactly what is happening internally: First you go the parent node, then remove the reference to the child node.

As of DOM4, a helper function is provided to do the same thing: element.remove(). This works in 96% of browsers (as of 2020), but not IE 11. If you need to support older browsers, you can:

How to read Data from Excel sheet in selenium webdriver

import jxl.Sheet;
import jxl.Workbook;

String FilePath = "/home/lahiru/Desktop/Sample.xls";
FileInputStream fs = new FileInputStream(FilePath);
Workbook wb = Workbook.getWorkbook(fs);

String <variable> = sh.getCell("A2").getContents();

List an Array of Strings in alphabetical order

You can just use Arrays#sort(), it's working perfectly. See this example :

String [] a = {"English","German","Italian","Korean","Blablablabla.."};
//before sort
for(int i = 0;i<a.length;i++)
System.out.println("After sort :");
for(int i = 0;i<a.length;i++)

OpenJDK availability for Windows OS

Only OpenJDK 7. OpenJDK6 is basically the same code base as SUN's version, that's why it redirects you to the official Oracle site.

How to count digits, letters, spaces for a string in Python?

Following code replaces any nun-numeric character with '', allowing you to count number of such characters with function len.

import re
len(re.sub("[^0-9]", "", my_string))


import re
len(re.sub("[^a-zA-Z]", "", my_string))

More info -

ReflectionException: Class ClassName does not exist - Laravel

composer update 

Above command worked for me.

Whenever you make new migration in la-ravel you need to refresh classmap in composer.json file .

How to display PDF file in HTML?

In html page for pc is easy to implement

<embed src="study/sample.pdf" type="application/pdf"   height="300px" width="100%">

but pdf show in mobile by this code is not possible you must need a plugin

if you have not responsive your site. Then above code pdf not show in mobile but you can put download option after the code

<embed src="study/sample.pdf" type="application/pdf"   height="300px" width="100%" class="responsive">
<a href="study/sample.pdf">download</a>

PHP "php://input" vs $_POST

So I wrote a function that would get the POST data from the php://input stream.

So the challenge here was switching to PUT, DELETE OR PATCH request method, and still obtain the post data that was sent with that request.

I'm sharing this maybe for someone with a similar challenge. The function below is what I came up with and it works. I hope it helps!

     * @method Post getPostData
     * @return array
     * Convert Content-Disposition to a post data
    function getPostData() : array
        // @var string $input
        $input = file_get_contents('php://input');

        // continue if $_POST is empty
        if (strlen($input) > 0 && count($_POST) == 0 || count($_POST) > 0) :

            $postsize = "---".sha1(strlen($input))."---";

            preg_match_all('/([-]{2,})([^\s]+)[\n|\s]{0,}/', $input, $match);

            // update input
            if (count($match) > 0) $input = preg_replace('/([-]{2,})([^\s]+)[\n|\s]{0,}/', '', $input);

            // extract the content-disposition
            preg_match_all("/(Content-Disposition: form-data; name=)+(.*)/m", $input, $matches);

            // let's get the keys
            if (count($matches) > 0 && count($matches[0]) > 0)
                $keys = $matches[2];

                foreach ($keys as $index => $key) :
                    $key = trim($key);
                    $key = preg_replace('/^["]/','',$key);
                    $key = preg_replace('/["]$/','',$key);
                    $key = preg_replace('/[\s]/','',$key);
                    $keys[$index] = $key;

                $input = preg_replace("/(Content-Disposition: form-data; name=)+(.*)/m", $postsize, $input);

                $input = preg_replace("/(Content-Length: )+([^\n]+)/im", '', $input);

                // now let's get key value
                $inputArr = explode($postsize, $input);

                // @var array $values
                $values = [];

                foreach ($inputArr as $index => $val) :
                    $val = preg_replace('/[\n]/','',$val);

                    if (preg_match('/[\S]/', $val)) $values[$index] = trim($val);


                // now combine the key to the values
                $post = [];

                // @var array $value
                $value = [];

                // update value
                foreach ($values as $i => $val) $value[] = $val;

                // push to post
                foreach ($keys as $x => $key) $post[$key] = isset($value[$x]) ? $value[$x] : '';

                if (is_array($post)) :

                    $newPost = [];

                    foreach ($post as $key => $val) :

                        if (preg_match('/[\[]/', $key)) :

                            $k = substr($key, 0, strpos($key, '['));
                            $child = substr($key, strpos($key, '['));
                            $child = preg_replace('/[\[|\]]/','', $child);
                            $newPost[$k][$child] = $val;


                            $newPost[$key] = $val;



                    $_POST = count($newPost) > 0 ? $newPost : $post;



        // return post array
        return $_POST;

How to set null to a GUID property

Guid? myGuidVar = (Guid?)null;

It could be. Unnecessary casting not required.

Guid? myGuidVar = null;

Winforms TableLayoutPanel adding rows programmatically

Here's my code for adding a new row to a two-column TableLayoutColumn:

private void AddRow(Control label, Control value)
    int rowIndex = AddTableRow();
    detailTable.Controls.Add(label, LabelColumnIndex, rowIndex);
    if (value != null)
        detailTable.Controls.Add(value, ValueColumnIndex, rowIndex);

private int AddTableRow()
    int index = detailTable.RowCount++;
    RowStyle style = new RowStyle(SizeType.AutoSize);
    return index;

The label control goes in the left column and the value control goes in the right column. The controls are generally of type Label and have their AutoSize property set to true.

I don't think it matters too much, but for reference, here is the designer code that sets up detailTable:

this.detailTable.ColumnCount = 2;
this.detailTable.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle());
this.detailTable.ColumnStyles.Add(new System.Windows.Forms.ColumnStyle());
this.detailTable.Dock = System.Windows.Forms.DockStyle.Fill;
this.detailTable.Location = new System.Drawing.Point(0, 0);
this.detailTable.Name = "detailTable";
this.detailTable.RowCount = 1;
this.detailTable.RowStyles.Add(new System.Windows.Forms.RowStyle());
this.detailTable.Size = new System.Drawing.Size(266, 436);
this.detailTable.TabIndex = 0;

This all works just fine. You should be aware that there appear to be some problems with disposing controls from a TableLayoutPanel dynamically using the Controls property (at least in some versions of the framework). If you need to remove controls, I suggest disposing the entire TableLayoutPanel and creating a new one.

How can I pass a parameter to a Java Thread?

In Java 8 you can use lambda expressions with the Concurrency API & the ExecutorService as a higher level replacement for working with threads directly:

newCachedThreadPool() Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available. These pools will typically improve the performance of programs that execute many short-lived asynchronous tasks.

    private static final ExecutorService executor = Executors.newCachedThreadPool();

    executor.submit(() -> {
        myFunction(myParam1, myParam2);

See also executors javadocs.

Superscript in CSS only?

The following is taken from Mozilla Firefox's internal html.css:

sup {
  vertical-align: super;
  font-size: smaller;
  line-height: normal;

So, in your case it would be something, like:

.superscript {
  vertical-align: super;
  font-size: smaller;
  line-height: normal;

how to check if string contains '+' character

Why not just:

int plusIndex = s.indexOf("+");
if (plusIndex != -1) {
    String before = s.substring(0, plusIndex);
    // Use before

It's not really clear why your original version didn't work, but then you didn't say what actually happened. If you want to split not using regular expressions, I'd personally use Guava:

Iterable<String> bits = Splitter.on('+').split(s);
String firstPart = Iterables.getFirst(bits, "");

If you're going to use split (either the built-in version or Guava) you don't need to check whether it contains + first - if it doesn't there'll only be one result anyway. Obviously there's a question of efficiency, but it's simpler code:

// Calling split unconditionally
String[] parts = s.split("\\+");
s = parts[0];

Note that writing String[] parts is preferred over String parts[] - it's much more idiomatic Java code.

Oracle SQL Query for listing all Schemas in a DB

Either of the following SQL will return all schema in Oracle DB.

  1. select owner FROM all_tables group by owner;
  2. select distinct owner FROM all_tables;

Detach (move) subdirectory into separate Git repository

I had exactly this problem but all the standard solutions based on git filter-branch were extremely slow. If you have a small repository then this may not be a problem, it was for me. I wrote another git filtering program based on libgit2 which as a first step creates branches for each filtering of the primary repository and then pushes these to clean repositories as the next step. On my repository (500Mb 100000 commits) the standard git filter-branch methods took days. My program takes minutes to do the same filtering.

It has the fabulous name of git_filter and lives here:

on GitHub.

I hope it is useful to someone.

Eclipse says: “Workspace in use or cannot be created, chose a different one.” How do I unlock a workspace?

I have observed one case when eclipse when in forced quit, or Alt-f2 xkilled in linux, an attempt to immediately open eclipse shows that error. Even the metadat/.lock file is not present in that case. However it starts working after a span of about two minutes

Efficient iteration with index in Scala

Some more ways to iterate:

scala>  xs.foreach (println) 

foreach, and similar, map, which would return something (the results of the function, which is, for println, Unit, so a List of Units)

scala> val lens = for (x <- xs) yield (x.length) 
lens: Array[Int] = Array(5, 6, 5)

work with the elements, not the index

scala> ("" /: xs) (_ + _) 
res21: java.lang.String = firstsecondthird


for(int i=0, j=0; i+j<100; i+=j*2, j+=i+2) {...}

can be done with recursion:

def ijIter (i: Int = 0, j: Int = 0, carry: Int = 0) : Int =
  if (i + j >= 100) carry else 
    ijIter (i+2*j, j+i+2, carry / 3 + 2 * i - 4 * j + 10) 

The carry-part is just some example, to do something with i and j. It needn't be an Int.

for simpler stuff, closer to usual for-loops:

scala> (1 until 4)
res43: scala.collection.immutable.Range with scala.collection.immutable.Range.ByOne = Range(1, 2, 3)

scala> (0 to 8 by 2)   
res44: scala.collection.immutable.Range = Range(0, 2, 4, 6, 8)

scala> (26 to 13 by -3)
res45: scala.collection.immutable.Range = Range(26, 23, 20, 17, 14)

or without order:

List (1, 3, 2, 5, 9, 7).foreach (print) 

How do write IF ELSE statement in a MySQL query

you must write it in SQL not it C/PHP style

IF( action = 2 AND state = 0, 1, 0 ) AS state

for use in query

IF ( action = 2 AND state = 0 ) THEN SET state = 1

for use in stored procedures or functions

How to make UIButton's text alignment center? Using IB

For those of you who are now using iOS 6 or higher, UITextAlignmentCenter has been deprecated. It is now NSTextAlignmentCenter

EXAMPLE: mylabel.textAlignment = NSTextAlignmentCenter; Works perfectly.

Converting ArrayList to HashMap


using your comment about productCode (and assuming product code is a String) as reference...

 for(Product p : productList){
        s.put(p.getProductCode() , p);

python filter list of dictionaries based on key value

Use filter, or if the number of dictionaries in exampleSet is too high, use ifilter of the itertools module. It would return an iterator, instead of filling up your system's memory with the entire list at once:

from itertools import ifilter
for elem in ifilter(lambda x: x['type'] in keyValList, exampleSet):
    print elem

EditText, clear focus on touch outside

Ken's answer works, but it is hacky. As pcans alludes to in the answer's comment, the same thing could be done with dispatchTouchEvent. This solution is cleaner as it avoids having to hack the XML with a transparent, dummy FrameLayout. Here is what that looks like:

public boolean dispatchTouchEvent(MotionEvent event) {
    EditText mEditText = findViewById(;
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        View v = getCurrentFocus();
        if (mEditText.isFocused()) {
            Rect outRect = new Rect();
            if (!outRect.contains((int)event.getRawX(), (int)event.getRawY())) {
                // Hide keyboard
                InputMethodManager imm = (InputMethodManager) v.getContext().getSystemService(Context.INPUT_METHOD_SERVICE); 
                imm.hideSoftInputFromWindow(v.getWindowToken(), 0);
    return super.dispatchTouchEvent(event);

Make docker use IPv4 for port binding

If you want your container ports to bind on your ipv4 address, just :

  • find the settings file
    • /etc/sysconfig/docker-network on RedHat alike
    • /etc/default/docker-network on Debian ans alike
  • edit the network settings
    • add DOCKER_NETWORK_OPTIONS=-ip=xx.xx.xx.xx
    • xx.xx.xx.xx being your real ipv4 (and not
  • restart docker deamon

works for me on docker 1.9.1

Background color on input type=button :hover state sticks in IE

Try using the type attribute selector to find buttons (maybe this'll fix it too):

  background-color: #E3E1B8; 

  background-color: #46000D

Why std::cout instead of simply cout?

It seems possible your class may have been using pre-standard C++. An easy way to tell, is to look at your old programs and check, do you see:

#include <iostream.h>


#include <iostream>

The former is pre-standard, and you'll be able to just say cout as opposed to std::cout without anything additional. You can get the same behavior in standard C++ by adding

using std::cout;


using namespace std;

Just one idea, anyway.

Difference between <input type='button' /> and <input type='submit' />

type='Submit' is set to forward & get the values on BACK-END (PHP, .NET etc). type='button' will reflect normal button behavior.

PostgreSQL - query from bash script as database user 'postgres'

Once you're logged in as postgres, you should be able to write:

psql -t -d database_name -c $'SELECT c_defaults FROM user_info WHERE c_uid = \'testuser\';'

to print out just the value of that field, which means that you can capture it to (for example) save in a Bash variable:

testuser_defaults="$(psql -t -d database_name -c $'SELECT c_defaults FROM user_info WHERE c_uid = \'testuser\';')"

To handle the logging in as postgres, I recommend using sudo. You can give a specific user the permission to run

sudo -u postgres /path/to/this/

so that they can run just the one script as postgres.

Limiting Powershell Get-ChildItem by File Creation Date Range

Use Where-Object, like:

Get-ChildItem 'PATH' -recurse -include @("*.tif*","*.jp2","*.pdf") | 
Where-Object { $_.CreationTime -gt "03/01/2013" -and $_.CreationTime -lt "03/31/2013" }
Select-Object FullName, CreationTime, @{Name="Mbytes";Expression={$_.Length/1Kb}}, @{Name="Age";Expression={(((Get-Date) - $_.CreationTime).Days)}} | 
Export-Csv 'PATH\scans.csv'

.attr('checked','checked') does not work


will not work with from jQuery 1.6.

Instead use


Full explanation / examples and demo can be found in the jQuery API Documentation

Symfony2 and date_default_timezone_get() - It is not safe to rely on the system's timezone settings

Found a similar way to fix this issue (at least it did for me).

  1. First check where the CLI php.ini is located:

    php -i | grep "php.ini"

  2. In my case I ended up with : Configuration File (php.ini) Path => /etc

  3. Then cd .. all the way back and cd into /etc, do ls in my case php.ini didn't show up, only a php.ini.default

  4. Now, copy the php.ini.default file named as php.ini:

    sudo cp php.ini.default php.ini

  5. In order to edit, change the permissions of the file:

    sudo chmod ug+w php.ini

    sudo chgrp staff php.ini

  6. Open directory and edit the php.ini file:

    open .

    Tip: If you are not able to edit the php.ini due to some permissions issue then copy 'php.ini.default' and paste it on your desktop and rename it to 'php.ini' then open it and edit it following step 7. Then move (copy+paste) it in /etc folder. Issue will be resolved.

  7. Search for [Date] and make sure the following line is in the correct format:

    date.timezone = "Europe/Amsterdam"

I hope this could help you out.

Excel: replace part of cell's string value

what you're looking for is SUBSTITUTE:


Will substitute Author for Authoring without messing with everything else

How to remove a variable from a PHP session array

Currently you are clearing the name array, you need to call the array then the index you want to unset within the array:


unset ($ar[2])

Two ways of unsetting values within an array:

# remove by key:
function array_remove_key ()
  $args  = func_get_args();
  return array_diff_key($args[0],array_flip(array_slice($args,1)));
# remove by value:
function array_remove_value ()
  $args = func_get_args();
  return array_diff($args[0],array_slice($args,1));

$fruit_inventory = array(
  'apples' => 52,
  'bananas' => 78,
  'peaches' => 'out of season',
  'pears' => 'out of season',
  'oranges' => 'no longer sold',
  'carrots' => 15,
  'beets' => 15,

echo "<pre>Original Array:\n",

# For example, beets and carrots are not fruits...
$fruit_inventory = array_remove_key($fruit_inventory,
echo "<pre>Array after key removal:\n",

# Let's also remove 'out of season' and 'no longer sold' fruit...
$fruit_inventory = array_remove_value($fruit_inventory,
                                      "out of season",
                                      "no longer sold");
echo "<pre>Array after value removal:\n",

So, unset has no effect to internal array counter!!!

How Should I Set Default Python Version In Windows?

This worked for me:

Go to

Control Panel\System and Security\System


Advanced system settings from the left panel
from Advanced tab click on Environment Variables

In the System variables section search for (create if doesn't exist)


and set


or your desired version

You need to restart CMD.

In case it still doesn't work you might want to leave in the PATH variable only your desired version.

The remote certificate is invalid according to the validation procedure

I had the same problem while I was testing a project and it turned that running Fiddler was the cause for this error..!!

If you are using Fiddler to intercept the http request, shut it down ...

This is one of the many causes for such error.

To fix Fiddler you may need to Reset Fiddler Https Certificates.

How to Migrate to WKWebView?

UIWebView will still continue to work with existing apps. WKWebView is available starting from iOS8, only WKWebView has a Nitro JavaScript engine.

To take advantage of this faster JavaScript engine in older apps you have to make code changes to use WKWebView instead of UIWebView. For iOS7 and older, you have to continue to use UIWebView, so you may have to check for iOS8 and then apply WKWebView methods / delegate methods and fallback to UIWebView methods for iOS7 and older. Also there is no Interface Builder component for WKWebView (yet), so you have to programmatically implement WKWebView.

You can implement WKWebView in Objective-C, here is simple example to initiate a WKWebView:

WKWebViewConfiguration *theConfiguration = [[WKWebViewConfiguration alloc] init];
WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.frame configuration:theConfiguration];
webView.navigationDelegate = self;
NSURL *nsurl=[NSURL URLWithString:@""];
NSURLRequest *nsrequest=[NSURLRequest requestWithURL:nsurl];
[webView loadRequest:nsrequest];
[self.view addSubview:webView];

WKWebView rendering performance is noticeable in WebGL games and something that runs complex JavaScript algorithms, if you are using webview to load a simple html or website, you can continue to use UIWebView.

Here is a test app that can used to open any website using either UIWebView or WKWebView and you can compare performance, and then decide on upgrading your app to use WKWebView:

enter image description here

How do I pass the this context to a function?

jQuery uses a .call(...) method to assign the current node to this inside the function you pass as the parameter.


Don't be afraid to look inside jQuery's code when you have a doubt, it's all in clear and well documented Javascript.

ie: the answer to this question is around line 574, object[ name ], name, object[ name ] ) === false

How to get the previous URL in JavaScript?

Those of you using Node.js and Express can set a session cookie that will remember the current page URL, thus allowing you to check the referrer on the next page load. Here's an example that uses the express-session middleware:

//Add me after the express-session middleware    
app.use((req, res, next) => {
    req.session.referrer = req.protocol + '://' + req.get('host') + req.originalUrl;

You can then check for the existance of a referrer cookie like so:

if ( req.session.referrer ) console.log(req.session.referrer);

Do not assume that a referrer cookie always exists with this method as it will not be available on instances where the previous URL was another website, the session was cleaned or was just created (first-time website load).

Changing background color of selected item in recyclerview

In your adapter class make Integer variable as index and assign it to "0" (if you want to select 1st item by default, if not assign "-1").Then on your onBindViewHolder method,

public void onBindViewHolder(@NonNull final ViewHolder holder, final int position) {
    holder.texttitle.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            index = position;
    if (index == position)

Thats it and you are good to If condition true section place your selected color or what ever you need, and else section place unselected color or what ever.

How do I convert a C# List<string[]> to a Javascript array?

Here's how you accomplish that:

<script type="text/javascript">
    var arrayOfArrays = JSON.parse('@Html.Raw(Json.Encode(Model.Addresses))');

How can I set NODE_ENV=production on Windows?

Current versions of Windows use Powershell as the default shell, so use:


Per @jsalonen's answer below. If you're in CMD (which is no longer maintained), use

set NODE_ENV=production

This should be executed in the command prompt where you intend to run your Node.js application.

The above line would set the environment variable NODE_ENV for the command prompt where you execute the command.

To set environment variables globally so they persist beyond just the single command prompt, you can find the tool from System in Control Panel (or by typing 'environment' into the search box in the start menu).

Best way to handle list.index(might-not-exist) in python?

If you are doing this often then it is better to stove it away in a helper function:

def index_of(val, in_list):
        return in_list.index(val)
    except ValueError:
        return -1 

How to remove the default arrow icon from a dropdown list (select element)?

Works for all browsers and all versions:


jQuery(document).ready(function () {    
    var widthOfSelect = $("#first").width();
    widthOfSelect = widthOfSelect - 13;
    jQuery('#first').wrap("<div id='sss' style='width: "+widthOfSelect+"px; overflow: hidden; border-right: #000 1px solid;' width=20></div>");


<select class="first" id="first">

Array and string offset access syntax with curly braces is deprecated

It's really simple to fix the issue, however keep in mind that you should fork and commit your changes for each library you are using in their repositories to help others as well.

Let's say you have something like this in your code:

$str = "test";

since PHP 7.4 curly braces method to get individual characters inside a string has been deprecated, so change the above syntax into this:

$str = "test";

Fixing the code in the question will look something like this:

public function getRecordID(string $zoneID, string $type = '', string $name = ''): string
    $records = $this->listRecords($zoneID, $type, $name);
    if (isset($records->result[0]->id)) {
        return $records->result[0]->id;
    return false;

I don't have "Dynamic Web Project" option in Eclipse new Project wizard

I had a similar problem, you may find that going to the top right corner of your page in Eclipse and click "Java EE" instead of "Java" will solve your problem. I had EE installed correctly like you, and this solved the issue for me. Hope I helped :)

How to include js file in another js file?

I disagree with the document.write technique (see suggestion of Vahan Margaryan). I like document.getElementsByTagName('head')[0].appendChild(...) (see suggestion of Matt Ball), but there is one important issue: the script execution order.

Recently, I have spent a lot of time reproducing one similar issue, and even the well-known jQuery plugin uses the same technique (see src here) to load the files, but others have also reported the issue. Imagine you have JavaScript library which consists of many scripts, and one loader.js loads all the parts. Some parts are dependent on one another. Imagine you include another main.js script per <script> which uses the objects from loader.js immediately after the loader.js. The issue was that sometimes main.js is executed before all the scripts are loaded by loader.js. The usage of $(document).ready(function () {/*code here*/}); inside of main.js script does not help. The usage of cascading onload event handler in the loader.js will make the script loading sequential instead of parallel, and will make it difficult to use main.js script, which should just be an include somewhere after loader.js.

By reproducing the issue in my environment, I can see that **the order of execution of the scripts in Internet Explorer 8 can differ in the inclusion of the JavaScript*. It is a very difficult issue if you need include scripts that are dependent on one another. The issue is described in Loading Javascript files in parallel, and the suggested workaround is to use document.writeln:

document.writeln("<script type='text/javascript' src='Script1.js'></script>");
document.writeln("<script type='text/javascript' src='Script2.js'></script>");

So in the case of "the scripts are downloaded in parallel but executed in the order they're written to the page", after changing from document.getElementsByTagName('head')[0].appendChild(...) technique to document.writeln, I had not seen the issue anymore.

So I recommend that you use document.writeln.

UPDATED: If somebody is interested, they can try to load (and reload) the page in Internet Explorer (the page uses the document.getElementsByTagName('head')[0].appendChild(...) technique), and then compare with the fixed version used document.writeln. (The code of the page is relatively dirty and is not from me, but it can be used to reproduce the issue).

Delete rows with foreign key in PostgreSQL

You can't delete a foreign key if it still references another table. First delete the reference

delete from kontakty
where id_osoby = 1;

WHERE id_osoby = 1;

Why doesn't wireshark detect my interface?

By Restarting NPF, I can see the interfaces with wireshark 1.6.5

Open a Command Prompt with administrative privileges.

  1. Execute the command "sc stop npf".
  2. Then start npf by command "sc start npf".
  3. Open WireShark.

That's it.

Full width image with fixed height

#image {
  width: 100%;
  height: 100px; //static
  object-fit: cover;

Hive: how to show all partitions of a table?

You can see Hive MetaStore tables,Partitions information in table of "PARTITIONS". You could use "TBLS" join "Partition" to query special table partitions.

Choosing line type and color in Gnuplot 4.0

Here is the syntax:

  set terminal pdf {monochrome|color|colour}
                   {fname "<font>"} {fsize <fontsize>}
                   {font "<fontname>{,<fontsize>}"}
                   {linewidth <lw>} {rounded|butt}
                   {solid|dashed} {dl <dashlength>}}
                   {size <XX>{unit},<YY>{unit}}

and an example:

set terminal pdfcairo monochrome enhanced font "Times-New-Roman,12" dashed

Undefined reference to main - collect2: ld returned 1 exit status

I my case I found out the void for the main function declaration was missing.

I was previously using Visual Studio in Windows and this was never a problem, so I thought I might leave it out now too.

Get Element value with minidom with Python

I know this question is pretty old now, but I thought you might have an easier time with ElementTree

from xml.etree import ElementTree as ET
import datetime

f = ET.XML(data)

for element in f:
    if element.tag == "currentTime":
        # Handle time data was pulled
        currentTime = datetime.datetime.strptime(element.text, "%Y-%m-%d %H:%M:%S")
    if element.tag == "cachedUntil":
        # Handle time until next allowed update
        cachedUntil = datetime.datetime.strptime(element.text, "%Y-%m-%d %H:%M:%S")
    if element.tag == "result":
        # Process list of skills

I know that's not super specific, but I just discovered it, and so far it's a lot easier to get my head around than the minidom (since so many nodes are essentially white space).

For instance, you have the tag name and the actual text together, just as you'd probably expect:

>>> element[0]
<Element currentTime at 40984d0>
>>> element[0].tag
>>> element[0].text
'2010-04-12 02:45:45'e

How do you Hover in ReactJS? - onMouseLeave not registered during fast hover over

Have you tried any of these?

onMouseDown onMouseEnter onMouseLeave onMouseMove onMouseOut onMouseOver onMouseUp


it also mentions the following:

React normalizes events so that they have consistent properties across different browsers.

The event handlers below are triggered by an event in the bubbling phase. To register an event handler for the capture phase, append Capture to the event name; for example, instead of using onClick, you would use onClickCapture to handle the click event in the capture phase.

Automatically open Chrome developer tools when new tab/new window is opened

You can open Dev Tools (F12 in Chrome) in new window by clicking three, vertical dots on the right bottom corner, and choose Open as Separate Window.

How to add custom validation to an AngularJS form?

In AngularJS the best place to define Custom Validation is Cutsom directive. AngularJS provide a ngMessages module.

ngMessages is a directive that is designed to show and hide messages based on the state of a key/value object that it listens on. The directive itself complements error message reporting with the ngModel $error object (which stores a key/value state of validation errors).

For custom form validation One should use ngMessages Modules with custom directive.Here i have a simple validation which will check if number length is less then 6 display an error on screen

 <form name="myform" novalidate>
                        <td><input name='test' type='text' required  ng-model='test' custom-validation></td>
                        <td ng-messages="myform.test.$error"><span ng-message="invalidshrt">Too Short</span></td>

Here is how to create custom validation directive

            require: 'ngModel',
            link:function (scope, element, attr, ctrl) {// 4th argument contain model information 

            function validationError(value) // you can use any function and parameter name 
                 if (value.length > 6) // if model length is greater then 6 it is valide state
                 ctrl.$setValidity('invalidshrt',false) //if less then 6 is invalide

                 return value; //return to display  error 
                ctrl.$parsers.push(validationError); //parsers change how view values will be saved in the model

$setValidity is inbuilt function to set model state to valid/invalid

How to enable zoom controls and pinch zoom in a WebView?

Use these:


How to extract multiple JSON objects from one file?

Added streaming support based on the answer of @dunes:

import re
from json import JSONDecoder, JSONDecodeError

NOT_WHITESPACE = re.compile(r"[^\s]")

def stream_json(file_obj, buf_size=1024, decoder=JSONDecoder()):
    buf = ""
    ex = None
    while True:
        block =
        if not block:
        buf += block
        pos = 0
        while True:
            match =, pos)
            if not match:
            pos = match.start()
                obj, pos = decoder.raw_decode(buf, pos)
            except JSONDecodeError as e:
                ex = e
                ex = None
                yield obj
        buf = buf[pos:]
    if ex is not None:
        raise ex

Meaning of - <?xml version="1.0" encoding="utf-8"?>

Can someone point me to a book or website which explains these basics clearly ?

You can check this XML Tutorial with examples.

But what about the encoding part ? Why is that necessary ?

W3C provides explanation about encoding :

"The document character set for XML and HTML 4.0 is Unicode (aka ISO 10646). This means that HTML browsers and XML processors should behave as if they used Unicode internally. But it doesn't mean that documents have to be transmitted in Unicode. As long as client and server agree on the encoding, they can use any encoding that can be converted to Unicode..."

python 2 instead of python 3 as the (temporary) default python?

mkdir ~/bin
ln -s /usr/bin/python2 ~/bin/python

To stop using python2, exit or rm ~/bin/python.

Is there a way to automatically build the package.json file for Node.js projects

npm add <package-name>

The above command will add the package to the node modules and update the package.json file

Make scrollbars only visible when a Div is hovered over?

The answer with changing overflow have a bunch of issues, like inconsistent width of the inner block and triggering of reflow.

There is an easier way to have the same effect that would not trigger reflow ever: using visibility property and nested blocks:

.scrollbox {_x000D_
  width: 10em;_x000D_
  height: 10em;_x000D_
  overflow: auto;_x000D_
  visibility: hidden;_x000D_
.scrollbox:focus {_x000D_
  visibility: visible;_x000D_
.scrollbox_delayed {_x000D_
  transition: visibility 0.2s;_x000D_
.scrollbox_delayed:hover {_x000D_
  transition: visibility 0s 0.2s;_x000D_
<h2>Hover it</h2>_x000D_
<div class="scrollbox" tabindex="0">_x000D_
  <div class="scrollbox-content">Hover me! Lorem ipsum dolor sit amet, consectetur adipisicing elit. Facere velit, repellat voluptas ipsa impedit fugiat voluptatibus. Facilis deleniti, nihil voluptate perspiciatis iure adipisci magni, nisi suscipit aliquam, quam, et excepturi! Lorem_x000D_
    ipsum dolor sit amet, consectetur adipisicing elit. Facere velit, repellat voluptas ipsa impedit fugiat voluptatibus. Facilis deleniti, nihil voluptate perspiciatis iure adipisci magni, nisi suscipit aliquam, quam, et excepturi!</div>_x000D_
<h2>With delay</h2>_x000D_
<div class="scrollbox scrollbox_delayed" tabindex="0">_x000D_
  <div class="scrollbox-content">Hover me! Lorem ipsum dolor sit amet, consectetur adipisicing elit. Facere velit, repellat voluptas ipsa impedit fugiat voluptatibus. Facilis deleniti, nihil voluptate perspiciatis iure adipisci magni, nisi suscipit aliquam, quam, et excepturi! Lorem_x000D_
    ipsum dolor sit amet, consectetur adipisicing elit. Facere velit, repellat voluptas ipsa impedit fugiat voluptatibus. Facilis deleniti, nihil voluptate perspiciatis iure adipisci magni, nisi suscipit aliquam, quam, et excepturi!</div>_x000D_

Another feature of this method is that visibility is animatable, so we can add a transition to it (see the second example in the pen above). Adding a transition would be better for UX: the scrollbar won't appear immediately when hovered just while moving along to another element, and it would be harder to miss the scrollbar when targeting it with mouse cursor, as it won't hide immediately as well.

Convert Existing Eclipse Project to Maven Project

I was having the same issue and wanted to Mavenise entire eclipse workspace containing around 60 Eclipse projects. Doing so manually required a lot of time and alternate options were not that viable. To solve the issue I finally created a project called eclipse-to-maven on github. As eclipse doesn't have all necessary information about the dependencies, it does the following:

  • Based on <classpathentry/> XML elements in .classpath file, it creates the dependencies on another project, identifies the library jar file and based on its name (for instance jakarta-oro-2.0.8.jar) identifies its version. Currently artifactId and groupId are same as I couldn't find something which could return me the Maven groupId of the dependency based on artifactId. Though this is not a perfect solution it provides a good ground to speed up Mavenisation.

  • It moves all source folders according to Maven convention (like src/main/java)

  • As Eclipse projects having names with spaces are difficult to deal on Linux/Unix environment, it renames them as well with names without spaces.

  • Resultant pom.xml files contain the dependencies and basic pom structure. You have to add required Maven plugins manually.

How to make <input type="file"/> accept only these types?

Use Like below

<input type="file" accept=".xlsx,.xls,image/*,.doc, .docx,.ppt, .pptx,.txt,.pdf" />

How to recover MySQL database from .myd, .myi, .frm files

I found a solution for converting the files to a .sql file (you can then import the .sql file to a server and recover the database), without needing to access the /var directory, therefore you do not need to be a server admin to do this either.

It does require XAMPP or MAMP installed on your computer.

  • After you have installed XAMPP, navigate to the install directory (Usually C:\XAMPP), and the the sub-directory mysql\data. The full path should be C:\XAMPP\mysql\data
  • Inside you will see folders of any other databases you have created. Copy & Paste the folder full of .myd, .myi and .frm files into there. The path to that folder should be


  • Then visit localhost/phpmyadmin in a browser. Select the database you have just pasted into the mysql\data folder, and click on Export in the navigation bar. Chooses the export it as a .sql file. It will then pop up asking where the save the file

And that is it! You (should) now have a .sql file containing the database that was originally .myd, .myi and .frm files. You can then import it to another server through phpMyAdmin by creating a new database and pressing 'Import' in the navigation bar, then following the steps to import it

How to sort List of objects by some property

You can call Collections.sort() and pass in a Comparator which you need to write to compare different properties of the object.

Preventing HTML and Script injections in Javascript

A one-liner:

var encodedMsg = $('<div />').text(message).html();

See it work:

How to convert a set to a list in python?

Python is a dynamically typed language, which means that you cannot define the type of the variable as you do in C or C++:

type variable = value


type variable(value)

In Python, you use coercing if you change types, or the init functions (constructors) of the types to declare a variable of a type:

my_set = set([1,2,3])
type my_set

will give you <type 'set'> for an answer.

If you have a list, do this:

my_list = [1,2,3]
my_set = set(my_list)

Get the time of a datetime using T-SQL?

Assuming the title of your question is correct and you want the time:


Edited to include millisecond.

Bootstrap 3, 4 and 5 .container-fluid with grid adding unwanted padding

In the new alpha versions they've introduced utility spacing classes. The structure can then be tweaked if you use them in a clever way.

Spacing utility classes

<div class="container-fluid">
    <div class="row">
        <div class="col-sm-4 col-md-3 pl-0">…</div>
        <div class="col-sm-4 col-md-3">…</div>
        <div class="col-sm-4 col-md-3">…</div>
        <div class="col-sm-4 col-md-3 pr-0">…</div>

pl-0 and pr-0 will remove leading and trailing padding from the columns. One issue left is the embedded rows of a column, as they still have negative margin. In this case:

<div class="col-sm-12 col-md-6 pl-0">
    <div class="row ml-0">

Version differences

Also note the utility spacing classes were changed since version 4.0.0-alpha.4. Before they were separated by 2 dashes e.g. => p-x-0 and p-l-0 and so on ...

To stay on topic for the version 3: This is what I use on Bootstrap 3 projects and include the compass setup, for this particular spacing utility, into bootstrap-sass (version 3) or bootstrap (version 4.0.0-alpha.3) with double dashes or bootstrap (version 4.0.0-alpha.4 and up) with single dashes.

Also, latest version(s) go up 'till 5 times a ratio (ex: pt-5 padding-top 5) instead of only 3.


$grid-breakpoints: (xs: 0, sm: 576px, md: 768px, lg: 992px, xl: 1200px) !default;

@import "../scss/mixins/breakpoints"; // media-breakpoint-up, breakpoint-infix
@import "../scss/utilities/_spacing.scss";

CSS output

You can ofcourse always copy/paste the padding spacing classes only from a generated css file.

.p-0 { padding: 0 !important; }
.pt-0 { padding-top: 0 !important; }
.pr-0 { padding-right: 0 !important; }
.pb-0 { padding-bottom: 0 !important; }
.pl-0 { padding-left: 0 !important; }
.px-0 { padding-right: 0 !important; padding-left: 0 !important; }
.py-0 { padding-top: 0 !important; padding-bottom: 0 !important; }
.p-1 { padding: 0.25rem !important; }
.pt-1 { padding-top: 0.25rem !important; }
.pr-1 { padding-right: 0.25rem !important; }
.pb-1 { padding-bottom: 0.25rem !important; }
.pl-1 { padding-left: 0.25rem !important; }
.px-1 { padding-right: 0.25rem !important; padding-left: 0.25rem !important; }
.py-1 { padding-top: 0.25rem !important; padding-bottom: 0.25rem !important; }
.p-2 { padding: 0.5rem !important; }
.pt-2 { padding-top: 0.5rem !important; }
.pr-2 { padding-right: 0.5rem !important; }
.pb-2 { padding-bottom: 0.5rem !important; }
.pl-2 { padding-left: 0.5rem !important; }
.px-2 { padding-right: 0.5rem !important; padding-left: 0.5rem !important; }
.py-2 { padding-top: 0.5rem !important; padding-bottom: 0.5rem !important; }
.p-3 { padding: 1rem !important; }
.pt-3 { padding-top: 1rem !important; }
.pr-3 { padding-right: 1rem !important; }
.pb-3 { padding-bottom: 1rem !important; }
.pl-3 { padding-left: 1rem !important; }
.px-3 { padding-right: 1rem !important; padding-left: 1rem !important; }
.py-3 { padding-top: 1rem !important; padding-bottom: 1rem !important; }
.p-4 { padding: 1.5rem !important; }
.pt-4 { padding-top: 1.5rem !important; }
.pr-4 { padding-right: 1.5rem !important; }
.pb-4 { padding-bottom: 1.5rem !important; }
.pl-4 { padding-left: 1.5rem !important; }
.px-4 { padding-right: 1.5rem !important; padding-left: 1.5rem !important; }
.py-4 { padding-top: 1.5rem !important; padding-bottom: 1.5rem !important; }
.p-5 { padding: 3rem !important; }
.pt-5 { padding-top: 3rem !important; }
.pr-5 { padding-right: 3rem !important; }
.pb-5 { padding-bottom: 3rem !important; }
.pl-5 { padding-left: 3rem !important; }
.px-5 { padding-right: 3rem !important; padding-left: 3rem !important; }
.py-5 { padding-top: 3rem !important; padding-bottom: 3rem !important; }

Error in launching AVD with AMD processor

First, you must enable Intel virtualization technology from the BIOS:

Enter image description here

Second, navigate to your SDK ...\extras\intel\Hardware_Accelerated_Execution_Manager:

Enter image description here

Then install intelhaxm-android.exe.

Note that if you can't find this file in the directory, make sure you install the package from your SDK manager:

Enter image description here

Java regex email

import java.util.Scanner;

public class CheckingTheEmailPassword {

    public static void main(String[] args) {
        String email = null;
        String password = null;
        Boolean password_valid = false;
        Boolean email_valid = false;

        Scanner input = new Scanner(;
        do {
            System.out.println("Enter your email: ");
            email = input.nextLine();

            System.out.println("Enter your passsword: ");
            password = input.nextLine();

            // checks for words,numbers before @symbol and between "@" and ".".
            // Checks only 2 or 3 alphabets after "."
            if (email.matches("[\\w]+@[\\w]+\\.[a-zA-Z]{2,3}"))
                email_valid = true;
                email_valid = false;

            // checks for NOT words,numbers,underscore and whitespace.
            // checks if special characters present
            if ((password.matches(".*[^\\w\\s].*")) &&
            // checks alphabets present
                    (password.matches(".*[a-zA-Z].*")) &&
                    // checks numbers present
                    (password.matches(".*[0-9].*")) &&
                    // checks length
                    (password.length() >= 8))
                password_valid = true;
                password_valid = false;

            if (password_valid && email_valid)
                System.out.println(" Welcome User!!");
            else {
                if (!email_valid)
                    System.out.println(" Re-enter your email: ");
                if (!password_valid)
                    System.out.println(" Re-enter your password: ");

        } while (!email_valid || !password_valid);




Sending emails with Javascript

If this is just going to open up the user's client to send the email, why not let them compose it there as well. You lose the ability to track what they are sending, but if that's not important, then just collect the addresses and subject and pop up the client to let the user fill in the body.

Match linebreaks - \n or \r\n?

In Python:

# as Peter van der Wal's answer
re.split(r'\r\n|\r|\n', text, flags=re.M) 

or more rigorous:


How can I insert vertical blank space into an html document?

Read up some on css, it's fun:

  .bottom-three {
     margin-bottom: 3cm;

<p class="bottom-three">
   This is the first question?
<p class="bottom-three">
   This is the second question?

New Line Issue when copying data from SQL Server 2012 to Excel

Seeing as this isn't already mentioned here and it's how I got around the issue...

Right click the target database and choose Tasks > Export data and follow that through. One of the destinations on the 'Choose a destination' screen is Microsoft Excel and there's a step that will accept your query.

It's the SQL Server Import and Export wizard. It's a lot more long-winded than the simple Copy with headers option that I normally use but, save jumping through a lot more hoops, when you have a lot of data to get into excel it's a worthy option.

jQuery remove options from select

find() takes a selector, not a value. This means you need to use it in the same way you would use the regular jQuery function ($('selector')).

Therefore you need to do something like this:


See the jQuery find docs.

What is an optional value in Swift?

An optional means that Swift is not entirely sure if the value corresponds to the type: for example, Int? means that Swift is not entirely sure whether the number is an Int.

To remove it, there are three methods you could employ.

1) If you are absolutely sure of the type, you can use an exclamation mark to force unwrap it, like this:

// Here is an optional variable:

var age: Int?

// Here is how you would force unwrap it:

var unwrappedAge = age!

If you do force unwrap an optional and it is equal to nil, you may encounter this crash error:

enter image description here

This is not necessarily safe, so here's a method that might prevent crashing in case you are not certain of the type and value:

Methods 2 and three safeguard against this problem.

2) The Implicitly Unwrapped Optional

 if let unwrappedAge = age {

 // continue in here


Note that the unwrapped type is now Int, rather than Int?.

3) The guard statement

 guard let unwrappedAge = age else { 
   // continue in here

From here, you can go ahead and use the unwrapped variable. Make sure only to force unwrap (with an !), if you are sure of the type of the variable.

Good luck with your project!

Why does Math.Round(2.5) return 2 instead of 3?

Here's the way i had to work it around :

Public Function Round(number As Double, dec As Integer) As Double
    Dim decimalPowerOfTen = Math.Pow(10, dec)
    If CInt(number * decimalPowerOfTen) = Math.Round(number * decimalPowerOfTen, 2) Then
        Return Math.Round(number, 2, MidpointRounding.AwayFromZero)
        Return CInt(number * decimalPowerOfTen + 0.5) / 100
    End If
End Function

Trying with 1.905 with 2 decimals will give 1.91 as expected but Math.Round(1.905,2,MidpointRounding.AwayFromZero) gives 1.90! Math.Round method is absolutely inconsistent and unusable for most of the basics problems programmers may encounter. I have to check if (int) 1.905 * decimalPowerOfTen = Math.Round(number * decimalPowerOfTen, 2) cause i don not want to round up what should be round down.

Wait some seconds without blocking UI execution

i really disadvise you against using Thread.Sleep(2000), because of a several reasons (a few are described here), but most of all because its not useful when it comes to debugging/testing.

I recommend to use a C# Timer instead of Thread.Sleep(). Timers let you perform methods frequently (if necessary) AND are much easiert to use in testing! There's a very nice example of how to use a timer right behind the hyperlink - just put your logic "what happens after 2 seconds" right into the Timer.Elapsed += new ElapsedEventHandler(OnTimedEvent); method.

NSPhotoLibraryUsageDescription key must be present in Info.plist to use camera roll


1. Open info.plist

enter image description here

2. Click this button to add a new key

enter image description here

3. Scroll down to find Privacy - Photo Library Usage Description

enter image description here

4. Select it, then add your description on the right

enter image description here

Set focus on <input> element

Easier way is also to do this.

let elementReference = document.querySelector('<your css, #id selector>');
    if (elementReference instanceof HTMLElement) {

JFrame.dispose() vs System.exit()

JFrame.dispose() affects only to this frame (release all of the native screen resources used by this component, its subcomponents, and all children). System.exit() affects to entire JVM.

If you want to close all JFrame or all Window (since Frames extend Windows) to terminate the application in an ordered mode, you can do some like this:

Arrays.asList(Window.getWindows()).forEach(e -> e.dispose()); // or JFrame.getFrames()

How to detect shake event with android?

Do the following:

private float xAccel, yAccel, zAccel;
private float xPreviousAccel, yPreviousAccel, zPreviousAccel;
private boolean firstUpdate = true;
private final float shakeThreshold = 1.5f;
private boolean shakeInitiated = false;
SensorEventListener mySensorEventListener;
SensorManager mySensorManager;

Put this in onCreate method.

mySensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);

And now the main part.

private boolean isAccelerationChanged() {
    float deltaX = Math.abs(xPreviousAccel - xAccel);
    float deltaY = Math.abs(yPreviousAccel - yAccel);
    float deltaZ = Math.abs(zPreviousAccel - zAccel);
    return (deltaX > shakeThreshold && deltaY > shakeThreshold)
            || (deltaX > shakeThreshold && deltaZ > shakeThreshold)
            || (deltaY > shakeThreshold && deltaZ > shakeThreshold);

private void updateAccelParameters(float xNewAccel, float yNewAccel, float zNewAccel) {
    if (firstUpdate) {
        xPreviousAccel = xNewAccel;
        yPreviousAccel = yNewAccel;
        zPreviousAccel = zNewAccel;
        firstUpdate = false;
        xPreviousAccel = xAccel;
        yPreviousAccel = yAccel;
        zPreviousAccel = zAccel;
    xAccel = xNewAccel;
    yAccel = yNewAccel;
    zAccel = zNewAccel;

private void executeShakeAction() {
    //this method is called when devices shakes

public void onSensorChanged(SensorEvent se) {
    updateAccelParameters(se.values[0], se.values[1], se.values[2]);
    if ((!shakeInitiated) && isAccelerationChanged()) {
        shakeInitiated = true;
    }else if ((shakeInitiated) && isAccelerationChanged()){
    }else if((shakeInitiated) && (!isAccelerationChanged())){
        shakeInitiated = false;

public void onAccuracyChanged(Sensor sensor, int accuracy) {
    //setting the accuracy

How to use lifecycle method getDerivedStateFromProps as opposed to componentWillReceiveProps

About the removal of componentWillReceiveProps: you should be able to handle its uses with a combination of getDerivedStateFromProps and componentDidUpdate, see the React blog post for example migrations. And yes, the object returned by getDerivedStateFromProps updates the state similarly to an object passed to setState.

In case you really need the old value of a prop, you can always cache it in your state with something like this:

state = {
  cachedSomeProp: null
  // ... rest of initial state

static getDerivedStateFromProps(nextProps, prevState) {
  // do things with nextProps.someProp and prevState.cachedSomeProp
  return {
    cachedSomeProp: nextProps.someProp,
    // ... other derived state properties

Anything that doesn't affect the state can be put in componentDidUpdate, and there's even a getSnapshotBeforeUpdate for very low-level stuff.

UPDATE: To get a feel for the new (and old) lifecycle methods, the react-lifecycle-visualizer package may be helpful.

Ruby on Rails 3 Can't connect to local MySQL server through socket '/tmp/mysql.sock' on OSX

On my machine mysqld service stopped that's why it was giving me the same problem.

1:- Go to terminal and type

sudo service mysqld restart

This will restart the mysqld service and create a new sock file on the required location.

Parse error: syntax error, unexpected T_ECHO in

Missing ; after var_dump($row)

How can I close a browser window without receiving the "Do you want to close this window" prompt?

Scripts are not allowed to close a window that a user opened. This is considered a security risk. Though it isn't in any standard, all browser vendors follow this (Mozilla docs). If this happens in some browsers, it's a security bug that (ideally) gets patched very quickly.

None of the hacks in the answers on this question work any longer, and if someone would come up with another dirty hack, eventually it will stop working as well.

I suggest you don't waste energy fighting this and embrace the method that the browser so helpfully gives you — ask the user before you seemingly crash their page.

How to install php-curl in Ubuntu 16.04


apt-get update

And then:

apt-get install php5-curl

How do I verify that a string only contains letters, numbers, underscores and dashes?

use a regex and see if it matches!


Delete specific line number(s) from a text file using sed?

This is very often a symptom of an antipattern. The tool which produced the line numbers may well be replaced with one which deletes the lines right away. For example;

grep -nh error logfile | cut -d: -f1 | deletelines logfile

(where deletelines is the utility you are imagining you need) is the same as

grep -v error logfile

Having said that, if you are in a situation where you genuinely need to perform this task, you can generate a simple sed script from the file of line numbers. Humorously (but perhaps slightly confusingly) you can do this with sed.

sed 's%$%d%' linenumbers

This accepts a file of line numbers, one per line, and produces, on standard output, the same line numbers with d appended after each. This is a valid sed script, which we can save to a file, or (on some platforms) pipe to another sed instance:

sed 's%$%d%' linenumbers | sed -f - logfile

On some platforms, sed -f does not understand the option argument - to mean standard input, so you have to redirect the script to a temporary file, and clean it up when you are done, or maybe replace the lone dash with /dev/stdin or /proc/$pid/fd/1 if your OS (or shell) has that.

As always, you can add -i before the -f option to have sed edit the target file in place, instead of producing the result on standard output. On *BSDish platforms (including OSX) you need to supply an explicit argument to -i as well; a common idiom is to supply an empty argument; -i ''.

Bootstrap Modal before form Submit

It is easy to solve, only create an hidden submit:

<button id="submitCadastro" type="button">ENVIAR</button>
<input type="submit" id="submitCadastroHidden" style="display: none;" >

with jQuery you click the submit:

    if($("#checkDocumentos").prop("checked") == false){
        //alert("Aceite os termos e condições primeiro!.");

Angular/RxJs When should I unsubscribe from `Subscription`

In my case I am using a variation of the solution proposed by @seanwright:

It's a file used in the ngx-rocket / starter-kit project. You can access it here until-destroyed.ts

The component would look like so

 * RxJS operator that unsubscribe from observables on destory.
 * Code forked from
 * IMPORTANT: Add the `untilDestroyed` operator as the last one to
 * prevent leaks with intermediate observables in the
 * operator chain.
 * @param instance The parent Angular component or object instance.
 * @param destroyMethodName The method to hook on (default: 'ngOnDestroy').
import { untilDestroyed } from '../../core/until-destroyed';

  selector: 'app-example',
  templateUrl: './example.component.html'
export class ExampleComponent implements OnInit, OnDestroy {

  ngOnInit() {
        .subscribe(val => console.log(val));

    // ...

  // This method must be present, even if empty.
  ngOnDestroy() {
    // To protect you, an error will be thrown if it doesn't exist.

Javascript - How to show escape characters in a string?

JavaScript uses the \ (backslash) as an escape characters for:

  • \' single quote
  • \" double quote
  • \ backslash
  • \n new line
  • \r carriage return
  • \t tab
  • \b backspace
  • \f form feed
  • \v vertical tab (IE < 9 treats '\v' as 'v' instead of a vertical tab ('\x0B'). If cross-browser compatibility is a concern, use \x0B instead of \v.)
  • \0 null character (U+0000 NULL) (only if the next character is not a decimal digit; else it’s an octal escape sequence)

Note that the \v and \0 escapes are not allowed in JSON strings.

What does $(function() {} ); do?

The following is a jQuery function call:


Which is the "jQuery function." $ is a function, and $(...) is you calling that function.

The first parameter you've supplied is the following:

function() {}

The parameter is a function that you specified, and the $ function will call the supplied method when the DOM finishes loading.

Operand type clash: uniqueidentifier is incompatible with int

The reason is that the data doesn't match the datatype. I have come across the same issues that I forgot to make the fields match. Though my case is not same as yours, but it shows the similar error message.

The situation is that I copy a table, but accidently I misspell one field, so I change it using the ALTER after creating the database. And the order of fields in both table is not identical. so when I use the INSERT INTO TableName SELECT * FROM TableName, the result showed the similar errors: Operand type clash: datetime is incompatible with uniqueidentifier

This is a simiple example:

use example
create table Test1 (
    id int primary key,
    item uniqueidentifier,
    inserted_at datetime
create table Test2 (
    id int primary key,
    inserted_at datetime
alter table Test2 add item uniqueidentifier;

--insert into Test1 (id, item, inserted_at) values (1, newid(), getdate()), (2, newid(), getdate());

insert into Test2 select * from Test1;

select * from Test1;
select * from Test2;

The error message is:

Msg 206, Level 16, State 2, Line 24
Operand type clash: uniqueidentifier is incompatible with datetime

What exactly does the "u" do? "git push -u origin master" vs "git push origin master"

All necessary git bash commands to push and pull into Github:

git status 
git pull
git add filefullpath

git commit -m "comments for checkin file" 
git push origin branch/master
git remote -v 
git log -2 

If you want to edit a file then:

edit filename.* 

To see all branches and their commits:

git show-branch

How to Correctly Check if a Process is running and Stop it

@jmp242 - the generic System.Object type does not contain the CloseMainWindow method, but statically casting the System.Diagnostics.Process type when collecting the ProcessList variable works for me. Updated code (from this answer) with this casting (and looping changed to use ForEach-Object) is below.

function Stop-Processes {
        [parameter(Mandatory=$true)] $processName,
                                     $timeout = 5
    [System.Diagnostics.Process[]]$processList = Get-Process $processName -ErrorAction SilentlyContinue

    ForEach ($Process in $processList) {
        # Try gracefully first
        $Process.CloseMainWindow() | Out-Null

    # Check the 'HasExited' property for each process
    for ($i = 0 ; $i -le $timeout; $i++) {
        $AllHaveExited = $True
        $processList | ForEach-Object {
            If (-NOT $_.HasExited) {
                $AllHaveExited = $False
        If ($AllHaveExited -eq $true){
        Start-Sleep 1
    # If graceful close has failed, loop through 'Stop-Process'
    $processList | ForEach-Object {
        If (Get-Process -ID $_.ID -ErrorAction SilentlyContinue) {
            Stop-Process -Id $_.ID -Force -Verbose

What is the difference between UTF-8 and Unicode?

They're not the same thing - UTF-8 is a particular way of encoding Unicode.

There are lots of different encodings you can choose from depending on your application and the data you intend to use. The most common are UTF-8, UTF-16 and UTF-32 s far as I know.

Media Queries: How to target desktop, tablet, and mobile?

The behavior does not change on desktop. But on tablets and mobiles, I expand the navbar to cover the big logo image. Note: Use the margin (top and bottom) as much as you need for your logo height.

For my case, 60px top and bottom worked perfectly!

@media (max-width:768px) { 
  .navbar-toggle {
      margin: 60px 0;

Check the navbar here.

Spring Boot: Unable to start EmbeddedWebApplicationContext due to missing EmbeddedServletContainerFactory bean

Clear repository is one possible solution.

Windows -> delete all subfolders in the maven repository:


Clearing _POST array fully

You can use a combination of both unset() and initialization:

$_POST = array();

Or in a single statement:

unset($_POST) ? $_POST = array() : $_POST = array();

But what is the reason you want to do this?

Angular HttpClient "Http failure during parsing"

I was facing the same issue in my Angular application. I was using RocketChat REST API in my application and I was trying to use the rooms.createDiscussion, but as an error as below.

ERROR Error: Uncaught (in promise): HttpErrorResponse: {"headers":{"normalizedNames":{},"lazyUpdate":null},"status":200,"statusText":"OK","url":"myurl/rocketchat/api/v1/rooms.createDiscussion","ok":false,"name":"HttpErrorResponse","message":"Http failure during parsing for myrul/rocketchat/api/v1/rooms.createDiscussion","error":{"error":{},"text":"

I have tried couple of things like changing the responseType: 'text' but none of them worked. At the end I was able to find the issue was with my RocketChat installation. As mentioned in the RocketChat change log the API rooms.createDiscussion is been introduced in the version 1.0.0 unfortunately I was using a lower version.

My suggestion is to check the REST API is working fine or not before you spend time to fix the error in your Angular code. I used curl command to check that.

curl -H "X-Auth-Token: token" -H "X-User-Id: userid" -H "Content-Type: application/json" myurl/rocketchat/api/v1/rooms.createDiscussion -d '{ "prid": "GENERAL", "t_name": "Discussion Name"}'

There as well I was getting an invalid HTML as a response.

<!DOCTYPE html>
<meta name="referrer" content="origin-when-crossorigin">
<script>/* eslint-disable */

'use strict';
(function() {
        var debounce = function debounce(func, wait, immediate) {

Instead of a valid JSON response as follows.

    "discussion": {
        "rid": "cgk88DHLHexwMaFWh",
        "name": "WJNEAM7W45wRYitHo",
        "fname": "Discussion Name",
        "t": "p",
        "msgs": 0,
        "usersCount": 0,
        "u": {
            "_id": "rocketchat.internal.admin.test",
            "username": "rocketchat.internal.admin.test"
        "topic": "general",
        "prid": "GENERAL",
        "ts": "2019-04-03T01:35:32.271Z",
        "ro": false,
        "sysMes": true,
        "default": false,
        "_updatedAt": "2019-04-03T01:35:32.280Z",
        "_id": "cgk88DHLHexwMaFWh"
    "success": true

So after updating to the latest RocketChat I was able to use the mentioned REST API.

How to search multiple columns in MySQL?


select *
from employee em
where CONCAT(em.firstname, ' ', em.lastname) like '%parth pa%';


select *
from employee em
where CONCAT_ws('-', em.firstname, em.lastname) like '%parth-pa%';

First is usefull when we have data like : 'firstname lastname'.


  • parth patel
  • parth p
  • patel parth

Second is usefull when we have data like : 'firstname-lastname'. In it you can also use special characters.


  • parth-patel
  • parth_p
  • patel#parth

Variable declaration in a header file

You can (should) declare it as extern in a header file, and define it in exactly 1 .c file.

Note that that .c file should also use the header and that the standard pattern looks like:

// file.h
extern int x;  // declaration

// file.c
#include "file.h"
int x = 1;    // definition and re-declaration

.htaccess File Options -Indexes on Subdirectories

htaccess files affect the directory they are placed in and all sub-directories, that is an htaccess file located in your root directory ( would affect,, etc.

Is there a C++ gdb GUI for Linux?

What can be stepped through is going to be limited by the debugging information that g++ produces, to a large extent. Emacs provides an interface to gdb that lets you control it via the toolbars/menus and display data in separate windows, as well as type gdb commands directly. Eclipse's CDT provides similar tools. I've heard of Anjuta and Code::Blocks but never used them.

Add a thousands separator to a total with Javascript or jQuery?

The $(this).html().replace(',', '') shouldn't actually modify the page. Are you sure the commas are being removed in the page?

If it is, this addCommas function should do the trick.

function addCommas(nStr) {
    nStr += '';
    var x = nStr.split('.');
    var x1 = x[0];
    var x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
        x1 = x1.replace(rgx, '$1' + ',' + '$2');
    return x1 + x2;

How to implement a Keyword Search in MySQL?

I will explain the method i usally prefer:

First of all you need to take into consideration that for this method you will sacrifice memory with the aim of gaining computation speed. Second you need to have a the right to edit the table structure.

1) Add a field (i usually call it "digest") where you store all the data from the table.

The field will look like:

"n-n1-n2-n3-n4-n5-n6-n7-n8-n9" etc.. where n is a single word

I achieve this using a regular expression thar replaces " " with "-". This field is the result of all the table data "digested" in one sigle string.

2) Use the LIKE statement %keyword% on the digest field:

SELECT * FROM table WHERE digest LIKE %keyword%

you can even build a qUery with a little loop so you can search for multiple keywords at the same time looking like:

 digest LIKE %keyword1% AND 
 digest LIKE %keyword2% AND 
 digest LIKE %keyword3% ... 

How to center an element horizontally and vertically

The simplest and cleanest solution for me is using the CSS3 property "transform":

.container {_x000D_
  position: relative;_x000D_
.container a {_x000D_
  position: absolute;_x000D_
  top: 50%;_x000D_
  transform: translate(0,-50%);_x000D_
<div class="container">_x000D_
  <a href="#">Hello world!</a>_x000D_

PHP function to generate v4 UUID

Use Symfony Polyfill / Uuid
Then you can just generate uuid as native php function:

$uuid = uuid_create(UUID_TYPE_RANDOM);

More about it, read in official Symfony blop post -

How to find index of all occurrences of element in array?

We can use Stack and push "i" into the stack every time we encounter the condition "arr[i]==value"

Check this:

static void getindex(int arr[], int value)
    Stack<Integer>st= new Stack<Integer>();
    int n= arr.length;
    for(int i=n-1; i>=0 ;i--)
        System.out.println(st.peek()+" ");

Is there a color code for transparent in HTML?

Here, instead of making navigation bar transparent, remove any color attributes from the navigation bar to make the background visible.

Strangely, I came across this thinking that I needed a transparent color, but all I needed is to remove the color attributes.

    background-color: #fafafa; 



Meaning of "n:m" and "1:n" in database design

n:m --> if you dont know both n and m it is simply many to many and it is represented by a bridge table between 2 other tables like

   -- This table will hold our phone calls.
CREATE TABLE dbo.PhoneCalls
   CallerPhoneNumber CHAR(10) NOT NULL

-- This table will hold our "tickets" (or cases).
CREATE TABLE dbo.Tickets
   Subject VARCHAR(250) NOT NULL,
   Notes VARCHAR(8000) NOT NULL,

this is the bridge table for implementing Mapping between 2 tables

CREATE TABLE dbo.PhoneCalls_Tickets
   PhoneCallID INT NOT NULL,

One to Many (1:n) is simply one table which has a column as primary key and another table which has this column as a foreign key relationship

Kind of like Product and Product Category where one product Category can have Many products

What is the most efficient way to concatenate N arrays?

It appears that the correct answer varies in different JS engines. Here are the results I got from the test suite linked in ninjagecko's answer:

  • [].concat.apply is fastest in Chrome 83 on Windows and Android, followed by reduce (~56% slower);
  • looped concat is fastest in Safari 13 on Mac, followed by reduce (~13% slower);
  • reduce is fastest in Safari 12 on iOS, followed by looped concat (~40% slower);
  • elementwise push is fastest in Firefox 70 on Windows, followed by [].concat.apply (~30% slower).

Unresponsive KeyListener for JFrame

You must add your keyListener to every component that you need. Only the component with the focus will send these events. For instance, if you have only one TextBox in your JFrame, that TextBox has the focus. So you must add a KeyListener to this component as well.

The process is the same:

myComponent.addKeyListener(new KeyListener ...);

Note: Some components aren't focusable like JLabel.

For setting them to focusable you need to:


what is the difference between uint16_t and unsigned short int incase of 64 bit processor?

uint16_t is unsigned 16-bit integer.

unsigned short int is unsigned short integer, but the size is implementation dependent. The standard only says it's at least 16-bit (i.e, minimum value of UINT_MAX is 65535). In practice, it usually is 16-bit, but you can't take that as guaranteed.


  1. If you want a portable unsigned 16-bit integer, use uint16_t.
  2. inttypes.h and stdint.h are both introduced in C99. If you are using C89, define your own type.
  3. uint16_t may not be provided in certain implementation(See reference below), but unsigned short int is always available.

Reference: C11(ISO/IEC 9899:201x) §7.20 Integer types

For each type described herein that the implementation provides) shall declare that typedef name and define the associated macros. Conversely, for each type described herein that the implementation does not provide, shall not declare that typedef name nor shall it define the associated macros. An implementation shall provide those types described as ‘‘required’’, but need not provide any of the others (described as ‘optional’’).

How do I solve this "Cannot read property 'appendChild' of null" error?

For all those facing a similar issue, I came across this same issue when i was trying to run a particular code snippet, shown below.

                var div, container = document.getElementById("container")
                for(var i=0;i<5;i++){
                    div = document.createElement("div");
                    div.onclick = function() { 
                        alert("This is a box #"+i);

        <div id="container"></div>

Looking at the error in the console for the above code.

Since the document.getElementById is returning a null and as null does not have a attribute named appendChild, therefore a error is thrown. To solve the issue see the code below.

            height: 200px;
            width: 700px;
            background-color: red;
            margin: 10px;

            height: 100px;
            width: 100px;
            background-color: purple;
            margin: 20px;
            display: inline-block;
        <div id="container"></div>
                var div, container = document.getElementById("container")
                for(let i=0;i<5;i++){
                    div = document.createElement("div");
                    div.onclick = function() { 
                        alert("This is a box #"+i);

I hope this helps. :)

How to create a GUID/UUID in Python

If you're using Python 2.5 or later, the uuid module is already included with the Python standard distribution.


>>> import uuid
>>> uuid.uuid4()

YAML mapping values are not allowed in this context

The elements of a sequence need to be indented at the same level. Assuming you want two jobs (A and B) each with an ordered list of key value pairs, you should use:

 - - name: A
   - schedule: "0 0/5 * 1/1 * ? *"
   - - type: mongodb.cluster
     - config:
       - host: mongodb://localhost:27017/admin?replicaSet=rs
       - minSecondaries: 2
       - minOplogHours: 100
       - maxSecondaryDelay: 120
 - - name: B
   - schedule: "0 0/5 * 1/1 * ? *"
   - - type: mongodb.cluster
     - config:
       - host: mongodb://localhost:27017/admin?replicaSet=rs
       - minSecondaries: 2
       - minOplogHours: 100
       - maxSecondaryDelay: 120

Converting the sequences of (single entry) mappings to a mapping as @Tsyvarrev does is also possible, but makes you lose the ordering.

How do I access command line arguments in Python?

Python tutorial explains it:

import sys


More specifically, if you run python one two three:

>>> import sys
>>> print(sys.argv)
['', 'one', 'two', 'three']

How to select all records from one table that do not exist in another table?

I'm going to repost (since I'm not cool enough yet to comment) in the correct case anyone else thought it needed better explaining.

FROM original_table_1 temp_table_1
LEFT JOIN original_table_2 temp_table_2 ON =

And I've seen syntax in FROM needing commas between table names in mySQL but in sqlLite it seemed to prefer the space.

The bottom line is when you use bad variable names it leaves questions. My variables should make more sense. And someone should explain why we need a comma or no comma.

How do I fetch lines before/after the grep result in bash?

The way to do this is near the top of the man page

grep -i -A 10 'error data'

How can I increase the JVM memory?

When calling java use the -Xmx Flag for example -Xmx512m for 512 megs for the heap size. You may also want to consider the -xms flag to start the heap larger if you are going to have it grow right from the start. The default size is 128megs.

CSS force image resize and keep aspect ratio

Remove the "height" property.

<img src="big_image.jpg" width="900" alt=""/>

By specifying both you are changing the aspect ratio of the image. Just setting one will resize but preserve the aspect ratio.

Optionally, to restrict oversizings:

<img src="big_image.jpg" width="900" alt="" style="max-width:500px; height:auto; max-height:600px;"/>

How to set background color of view transparent in React Native

Try to use transparent attribute value for making transparent background color.

backgroundColor: 'transparent'

(How) can I count the items in an enum?

Add a entry, at the end of your enum, called Folders_MAX or something similar and use this value when initializing your arrays.

ContainerClass* m_containers[Folders_MAX];

Take nth column in a text file

If your file contains n lines, then your script has to read the file n times; so if you double the length of the file, you quadruple the amount of work your script does — and almost all of that work is simply thrown away, since all you want to do is loop over the lines in order.

Instead, the best way to loop over the lines of a file is to use a while loop, with the condition-command being the read builtin:

while IFS= read -r line ; do
    # $line is a single line of the file, as a single string
    : ... commands that use $line ...
done < input_file.txt

In your case, since you want to split the line into an array, and the read builtin actually has special support for populating an array variable, which is what you want, you can write:

while read -r -a line ; do
    echo ""${line[1]}" "${line[3]}"" >> out.txt
done < /path/of/my/text

or better yet:

while read -r -a line ; do
    echo "${line[1]} ${line[3]}"
done < /path/of/my/text > out.txt

However, for what you're doing you can just use the cut utility:

cut -d' ' -f2,4 < /path/of/my/text > out.txt

(or awk, as Tom van der Woerdt suggests, or perl, or even sed).