Programs & Examples On #Web.xml

The web.xml is the web deployment descriptor file of Java Servlet based web applications. It allows you to define, declare and configure the Servlet API based implementations in your web application, such as servlets, filters and listeners.

Difference between / and /* in servlet mapping url pattern

<url-pattern>/*</url-pattern>

The /* on a servlet overrides all other servlets, including all servlets provided by the servletcontainer such as the default servlet and the JSP servlet. Whatever request you fire, it will end up in that servlet. This is thus a bad URL pattern for servlets. Usually, you'd like to use /* on a Filter only. It is able to let the request continue to any of the servlets listening on a more specific URL pattern by calling FilterChain#doFilter().

<url-pattern>/</url-pattern>

The / doesn't override any other servlet. It only replaces the servletcontainer's builtin default servlet for all requests which doesn't match any other registered servlet. This is normally only invoked on static resources (CSS/JS/image/etc) and directory listings. The servletcontainer's builtin default servlet is also capable of dealing with HTTP cache requests, media (audio/video) streaming and file download resumes. Usually, you don't want to override the default servlet as you would otherwise have to take care of all its tasks, which is not exactly trivial (JSF utility library OmniFaces has an open source example). This is thus also a bad URL pattern for servlets. As to why JSP pages doesn't hit this servlet, it's because the servletcontainer's builtin JSP servlet will be invoked, which is already by default mapped on the more specific URL pattern *.jsp.

<url-pattern></url-pattern>

Then there's also the empty string URL pattern . This will be invoked when the context root is requested. This is different from the <welcome-file> approach that it isn't invoked when any subfolder is requested. This is most likely the URL pattern you're actually looking for in case you want a "home page servlet". I only have to admit that I'd intuitively expect the empty string URL pattern and the slash URL pattern / be defined exactly the other way round, so I can understand that a lot of starters got confused on this. But it is what it is.

Front Controller

In case you actually intend to have a front controller servlet, then you'd best map it on a more specific URL pattern like *.html, *.do, /pages/*, /app/*, etc. You can hide away the front controller URL pattern and cover static resources on a common URL pattern like /resources/*, /static/*, etc with help of a servlet filter. See also How to prevent static resources from being handled by front controller servlet which is mapped on /*. Noted should be that Spring MVC has a builtin static resource servlet, so that's why you could map its front controller on / if you configure a common URL pattern for static resources in Spring. See also How to handle static content in Spring MVC?

How to specify the default error page in web.xml?

You can also specify <error-page> for exceptions using <exception-type>, eg below:

<error-page>
    <exception-type>java.lang.Exception</exception-type>
    <location>/errorpages/exception.html</location>
</error-page>

Or map a error code using <error-code>:

<error-page>
    <error-code>404</error-code>
    <location>/errorpages/404error.html</location>
</error-page>

What does the servlet <load-on-startup> value signify

--> (Absence of load-on-start-up) tag First of all when ever servlet is deployed in the server, It is the responsibility of the server to creates the servlet object. Eg: Suppose Servlet is deployed in the server ,(Servlet Object is not available in server) client sends the request to the servlet for the first time then server creates the servlet object with help of default constructor and immediately calls init() . From that when ever client sends the request only service method will get executed as object is already available

If load-on-start-up tag is used in deployment descriptor: At the time of deployment itself the server creates the servlet object for the servlets based on the positive value provided in between the tags. The Creation of objects for the servlet classes will follow from 0-128 0 number servlet will be created first and followed by other numbers.

If we provide same value for two servlets in web.xml then creation of objects will be done based on the position of classes in web.xml also varies from server to server.

If we provide negative value in between the load on start up tag then server wont create the servlet object.

Other Scenarios where server creates the object for servlet.

If we dont use load on start up tag in web.xml, then project is deployed when ever client sends the request for the first time server creates the object and server is responsible for calling its life cycle methods. Then if a .class is been modified in the server(tomcat). again client sends the request for modified servlet but in case of tomcat new object will not created and server make use of existing object unless restart of server takes place. But in class of web-logic when ever .class file is modified in the server with out restarting the server if it receives a request then server calls the destroy method on existing servlet and creates a new servlet object and calls init() for its initilization.

How to register multiple servlets in web.xml in one Spring application

I know this is a bit old but the answer in short would be <load-on-startup> both occurrences have given the same id which is 1 twice. This may confuse loading sequence.

Could not open ServletContext resource

I think currently the application-context.xml file is into src/main/resources AND the social.properties file is into src/main/java... so when you package (mvn package) or when you run tomcat (mvn tomcat:run) your social.properties disappeared (I know you said when you checked into the .war the files are here... but your exception says the opposite).

The solution is simply to put all your configuration files (application-context.xml and social.properties) into src/main/resources to follow the maven standard structure.

What is resource-ref in web.xml used for?

You can always refer to resources in your application directly by their JNDI name as configured in the container, but if you do so, essentially you are wiring the container-specific name into your code. This has some disadvantages, for example, if you'll ever want to change the name later for some reason, you'll need to update all the references in all your applications, and then rebuild and redeploy them.

<resource-ref> introduces another layer of indirection: you specify the name you want to use in the web.xml, and, depending on the container, provide a binding in a container-specific configuration file.

So here's what happens: let's say you want to lookup the java:comp/env/jdbc/primaryDB name. The container finds that web.xml has a <resource-ref> element for jdbc/primaryDB, so it will look into the container-specific configuration, that contains something similar to the following:

<resource-ref>
  <res-ref-name>jdbc/primaryDB</res-ref-name>
  <jndi-name>jdbc/PrimaryDBInTheContainer</jndi-name>
</resource-ref>

Finally, it returns the object registered under the name of jdbc/PrimaryDBInTheContainer.

The idea is that specifying resources in the web.xml has the advantage of separating the developer role from the deployer role. In other words, as a developer, you don't have to know what your required resources are actually called in production, and as the guy deploying the application, you will have a nice list of names to map to real resources.

Session TimeOut in web.xml

Hacky way:

You could increase the session timeout programmatically when a large up-/download is expected.

session.setMaxInactiveInterval(TWO_HOURS_IN_SECONDS)

When the process ends, you could set the timeout back to its default.

But.. when you are on Java EE, and the up-/download doesn't take a complete hour, the better way was to run the tasks asynchronous (via JMS e.g.).

No WebApplicationContext found: no ContextLoaderListener registered?

And if you would like to use an existing context, rather than a new context which would be loaded from xml configuration by org.springframework.web.context.ContextLoaderListener, then see -> https://stackoverflow.com/a/40694787/3004747

Why do we use web.xml?

The web.xml file is the deployment descriptor for a Servlet-based Java web application (which most Java web apps are). Among other things, it declares which Servlets exist and which URLs they handle.

The part you cite defines a Servlet Filter. Servlet filters can do all kinds of preprocessing on requests. Your specific example is a filter had the Wicket framework uses as its entry point for all requests because filters are in some way more powerful than Servlets.

SEVERE: ContainerBase.addChild: start:org.apache.catalina.LifecycleException: Failed to start error

In my case the servlet name defined in the web.xml was not same as the sevlet name in the servlet mapping tag. I have corrected this and the WAR was deployed successfully.

What is web.xml file and what are all things can I do with it?

http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">

<servlet>
    <servlet-name>mvc-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>mvc-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value>
</context-param>

<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>

How to configure welcome file list in web.xml

I saw a nice solution in this stackoverflow link that may help the readers of the defulat servlet handling issue by using the empty string URL pattern "" :

@WebServlet("")

or

<servlet-mapping>
    <servlet-name>yourHomeServlet</servlet-name>
    <url-pattern></url-pattern> <!-- Yes, empty string! -->
</servlet-mapping>

What is the significance of url-pattern in web.xml and how to configure servlet?

Servlet-mapping has two child tags, url-pattern and servlet-name. url-pattern specifies the type of urls for which, the servlet given in servlet-name should be called. Be aware that, the container will use case-sensitive for string comparisons for servlet matching.

First specification of url-pattern a web.xml file for the server context on the servlet container at server .com matches the pattern in <url-pattern>/status/*</url-pattern> as follows:

http://server.com/server/status/synopsis               = Matches
http://server.com/server/status/complete?date=today    = Matches
http://server.com/server/status                        = Matches
http://server.com/server/server1/status                = Does not match

Second specification of url-pattern A context located at the path /examples on the Agent at example.com matches the pattern in <url-pattern>*.map</url-pattern> as follows:

 http://server.com/server/US/Oregon/Portland.map    = Matches
 http://server.com/server/US/server/Seattle.map     = Matches
 http://server.com/server/Paris.France.map          = Matches
 http://server.com/server/US/Oregon/Portland.MAP    = Does not match, the extension is uppercase
 http://example.com/examples/interface/description/mail.mapi  =Does not match, the extension is mapi rather than map`

Third specification of url-mapping,A mapping that contains the pattern <url-pattern>/</url-pattern> matches a request if no other pattern matches. This is the default mapping. The servlet mapped to this pattern is called the default servlet.

The default mapping is often directed to the first page of an application. Explicitly providing a default mapping also ensures that malformed URL requests into the application return are handled by the application rather than returning an error.

The servlet-mapping element below maps the server servlet instance to the default mapping.

<servlet-mapping>
  <servlet-name>server</servlet-name>
  <url-pattern>/</url-pattern>
</servlet-mapping>

For the context that contains this element, any request that is not handled by another mapping is forwarded to the server servlet.

And Most importantly we should Know about Rule for URL path mapping

  1. The container will try to find an exact match of the path of the request to the path of the servlet. A successful match selects the servlet.
  2. The container will recursively try to match the longest path-prefix. This is done by stepping down the path tree a directory at a time, using the ’/’ character as a path separator. The longest match determines the servlet selected.
  3. If the last segment in the URL path contains an extension (e.g. .jsp), the servlet container will try to match a servlet that handles requests for the extension. An extension is defined as the part of the last segment after the last ’.’ character.
  4. If neither of the previous three rules result in a servlet match, the container will attempt to serve content appropriate for the resource requested. If a “default” servlet is defined for the application, it will be used.

Reference URL Pattern

Loading context in Spring using web.xml

You can also load the context while defining the servlet itself (WebApplicationContext)

  <servlet>
    <servlet-name>admin</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>
                /WEB-INF/spring/*.xml
            </param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>admin</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>

rather than (ApplicationContext)

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/applicationContext*.xml</param-value>
</context-param>

<listener>
   <listener-class>
        org.springframework.web.context.ContextLoaderListener
   </listener-class>
</listener> 

or can do both together.

Drawback of just using WebApplicationContext is that it will load context only for this particular Spring entry point (DispatcherServlet) where as with above mentioned methods context will be loaded for multiple entry points (Eg. Webservice Servlet, REST servlet etc)

Context loaded by ContextLoaderListener will infact be a parent context to that loaded specifically for DisplacherServlet . So basically you can load all your business service, data access or repository beans in application context and separate out your controller, view resolver beans to WebApplicationContext.

How to define servlet filter order of execution using annotations in WAR

  1. Make the servlet filter implement the spring Ordered interface.
  2. Declare the servlet filter bean manually in configuration class.
    import org.springframework.core.Ordered;
    
    public class MyFilter implements Filter, Ordered {

        @Override
        public void init(FilterConfig filterConfig) {
            // do something
        }

        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            // do something
        }

        @Override
        public void destroy() {
            // do something
        }

        @Override
        public int getOrder() {
            return -100;
        }
    }


    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;

    @Configuration
    @ComponentScan
    public class MyAutoConfiguration {

        @Bean
        public MyFilter myFilter() {
            return new MyFilter();
        }
    }

PreparedStatement with Statement.RETURN_GENERATED_KEYS

private void alarmEventInsert(DriveDetail driveDetail, String vehicleRegNo, int organizationId) {

    final String ALARM_EVENT_INS_SQL = "INSERT INTO alarm_event (event_code,param1,param2,org_id,created_time) VALUES (?,?,?,?,?)";
    CachedConnection conn = JDatabaseManager.getConnection();
    PreparedStatement ps = null;
    ResultSet generatedKeys = null;
    try {
        ps = conn.prepareStatement(ALARM_EVENT_INS_SQL, ps.RETURN_GENERATED_KEYS);
        ps.setInt(1, driveDetail.getEventCode());
        ps.setString(2, vehicleRegNo);
        ps.setString(3, null);
        ps.setInt(4, organizationId);
        ps.setString(5, driveDetail.getCreateTime());
        ps.execute();
        generatedKeys = ps.getGeneratedKeys();
        if (generatedKeys.next()) {
            driveDetail.setStopDuration(generatedKeys.getInt(1));
        }
    } catch (SQLException e) {
        e.printStackTrace();
        logger.error("Error inserting into alarm_event : {}", e
                .getMessage());
        logger.info(ps.toString());
    } finally {
        if (ps != null) {
            try {

                if (ps != null)
                    ps.close();
            } catch (SQLException e) {
                logger.error("Error closing prepared statements : {}", e
                        .getMessage());
            }
        }
    }
    JDatabaseManager.freeConnection(conn);
}

Character reading from file in Python

Not sure about the (errors="ignore") option but it seems to work for files with strange Unicode characters.

with open(fName, "rb") as fData:
    lines = fData.read().splitlines()
    lines = [line.decode("utf-8", errors="ignore") for line in lines]

How can a LEFT OUTER JOIN return more records than exist in the left table?

Could it be a one to many relationship between the left and right tables?

Laravel Mail::send() sending to multiple to or bcc addresses

If you want to send emails simultaneously to all the admins, you can do something like this:

In your .env file add all the emails as comma separated values:

[email protected],[email protected],[email protected]

so when you going to send the email just do this (yes! the 'to' method of message builder instance accepts an array):

So,

$to = explode(',', env('ADMIN_EMAILS'));

and...

$message->to($to);

will now send the mail to all the admins.

Comparing two collections for equality irrespective of the order of items in them

Here is a solution which is an improvement over this one.

public static bool HasSameElementsAs<T>(
        this IEnumerable<T> first, 
        IEnumerable<T> second, 
        IEqualityComparer<T> comparer = null)
    {
        var firstMap = first
            .GroupBy(x => x, comparer)
            .ToDictionary(x => x.Key, x => x.Count(), comparer);

        var secondMap = second
            .GroupBy(x => x, comparer)
            .ToDictionary(x => x.Key, x => x.Count(), comparer);

        if (firstMap.Keys.Count != secondMap.Keys.Count)
            return false;

        if (firstMap.Keys.Any(k1 => !secondMap.ContainsKey(k1)))
            return false;

        return firstMap.Keys.All(x => firstMap[x] == secondMap[x]);
    }

Set value of hidden field in a form using jQuery's ".val()" doesn't work

Simply use syntax below get and set

GET

//Script 
var a = $("#selectIndex").val();

here a variable will hold the value of hiddenfield(selectindex)

Server side

<asp:HiddenField ID="selectIndex" runat="server" Value="0" />

SET

var a =10;
$("#selectIndex").val(a);

Url decode UTF-8 in Python

If you are using Python 3, you can use urllib.parse

url = """example.com?title=%D0%BF%D1%80%D0%B0%D0%B2%D0%BE%D0%B2%D0%B0%D1%8F+%D0%B7%D0%B0%D1%89%D0%B8%D1%82%D0%B0"""

import urllib.parse
urllib.parse.unquote(url)

gives:

'example.com?title=????????+??????'

PHPMyAdmin Default login password

This is asking for your MySQL username and password.

You should enter these details, which will default to "root" and "" (i.e.: nothing) if you've not specified a password.

How can I upload fresh code at github?

If you haven't already created the project in Github, do so on that site. If memory serves, they display a page that tells you exactly how to get your existing code into your new repository. At the risk of oversimplification, though, you'd follow Veeti's instructions, then:

git remote add [name to use for remote] [private URI] # associate your local repository to the remote
git push [name of remote] master # push your repository to the remote

How do I import global modules in Node? I get "Error: Cannot find module <module>"?

If you're using npm >=1.0, you can use npm link <global-package> to create a local link to a package already installed globally. (Caveat: The OS must support symlinks.)

However, this doesn't come without its problems.

npm link is a development tool. It's awesome for managing packages on your local development box. But deploying with npm link is basically asking for problems, since it makes it super easy to update things without realizing it.

As an alternative, you can install the packages locally as well as globally.

For additional information, see

$('body').on('click', '.anything', function(){})

If you want to capture click on everything then do

$("*").click(function(){
//code here
}

I use this for selector: http://api.jquery.com/all-selector/

This is used for handling clicks: http://api.jquery.com/click/

And then use http://api.jquery.com/event.preventDefault/

To stop normal clicking actions.

How to use clock() in C++

clock() returns the number of clock ticks since your program started. There is a related constant, CLOCKS_PER_SEC, which tells you how many clock ticks occur in one second. Thus, you can test any operation like this:

clock_t startTime = clock();
doSomeOperation();
clock_t endTime = clock();
clock_t clockTicksTaken = endTime - startTime;
double timeInSeconds = clockTicksTaken / (double) CLOCKS_PER_SEC;

Convert Datetime column from UTC to local time in select statement

Best way for Oracle:

With hardcoded datetime:

SELECT TO_CHAR(CAST((FROM_TZ(CAST(TO_DATE('2018-10-27 21:00', 'YYYY-MM-DD HH24:MI') AS TIMESTAMP), 'UTC') AT  TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM DUAL

Result: 2018-10-28 00:00

With column and table names:

SELECT TO_CHAR(CAST((FROM_TZ(CAST(COLUMN_NAME AS TIMESTAMP), 'UTC') AT  TIME ZONE 'EET') AS DATE), 'YYYY-MM-DD HH24:MI') UTC_TO_EET FROM TABLE_NAME

How to create directory automatically on SD card

     //Create File object for Parent Directory
File wallpaperDir = new File(Environment.getExternalStorageDirectory().getAbsoluteFile() +File.separator + "wallpaper");
if (!wallpaperDir.exists()) {
wallpaperDir.mkdir();
}


File out = new File(wallpaperDir, wallpaperfile);
FileOutputStream outputStream = new FileOutputStream(out);

How to use the unsigned Integer in Java 8 and Java 9?

    // Java 8
    int vInt = Integer.parseUnsignedInt("4294967295");
    System.out.println(vInt); // -1
    String sInt = Integer.toUnsignedString(vInt);
    System.out.println(sInt); // 4294967295

    long vLong = Long.parseUnsignedLong("18446744073709551615");
    System.out.println(vLong); // -1
    String sLong = Long.toUnsignedString(vLong);
    System.out.println(sLong); // 18446744073709551615

    // Guava 18.0
    int vIntGu = UnsignedInts.parseUnsignedInt(UnsignedInteger.MAX_VALUE.toString());
    System.out.println(vIntGu); // -1
    String sIntGu = UnsignedInts.toString(vIntGu);
    System.out.println(sIntGu); // 4294967295

    long vLongGu = UnsignedLongs.parseUnsignedLong("18446744073709551615");
    System.out.println(vLongGu); // -1
    String sLongGu = UnsignedLongs.toString(vLongGu);
    System.out.println(sLongGu); // 18446744073709551615

    /**
     Integer - Max range
     Signed: From -2,147,483,648 to 2,147,483,647, from -(2^31) to 2^31 – 1
     Unsigned: From 0 to 4,294,967,295 which equals 2^32 - 1

     Long - Max range
     Signed: From -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807, from -(2^63) to 2^63 - 1
     Unsigned: From 0 to 18,446,744,073,709,551,615 which equals 2^64 – 1
     */

Regular expression for checking if capital letters are found consecutively in a string?

If you want to get all Employee name in mysql which having at least one uppercase letter than apply this query.

SELECT * FROM registration WHERE `name` REGEXP BINARY '[A-Z]';

Bootstrap 4 navbar color

I got it. This is very simple. Using the class bg you can achieve this easily.

Let me show you:

<nav class="navbar navbar-expand-lg navbar-dark navbar-full bg-primary"></nav>

This gives you the default blue navbar

If you want to change your favorite color, then simply use the style tag within the nav:

<nav class="navbar navbar-expand-lg navbar-dark navbar-full" style="background-color: #FF0000">

Why doesn't margin:auto center an image?

<div style="text-align:center;">
    <img src="queuedError.jpg" style="margin:auto; width:200px;" />
</div>

Apply pandas function to column to create multiple new columns?

This is the correct and easiest way to accomplish this for 95% of use cases:

>>> df = pd.DataFrame(zip(*[range(10)]), columns=['num'])
>>> df
    num
0    0
1    1
2    2
3    3
4    4
5    5

>>> def example(x):
...     x['p1'] = x['num']**2
...     x['p2'] = x['num']**3
...     x['p3'] = x['num']**4
...     return x

>>> df = df.apply(example, axis=1)
>>> df
    num  p1  p2  p3
0    0   0   0    0
1    1   1   1    1
2    2   4   8   16
3    3   9  27   81
4    4  16  64  256

How to customize the configuration file of the official PostgreSQL Docker image?

When you run the official entrypoint (A.K.A. when you launch the container), it runs initdb in $PGDATA (/var/lib/postgresql/data by default), and then it stores in that directory these 2 files:

  • postgresql.conf with default manual settings.
  • postgresql.auto.conf with settings overriden automatically with ALTER SYSTEM commands.

The entrypoint also executes any /docker-entrypoint-initdb.d/*.{sh,sql} files.

All this means you can supply a shell/SQL script in that folder that configures the server for the next boot (which will be immediately after the DB initialization, or the next times you boot the container).

Example:

conf.sql file:

ALTER SYSTEM SET max_connections = 6;
ALTER SYSTEM RESET shared_buffers;

Dockerfile file:

FROM posgres:9.6-alpine
COPY *.sql /docker-entrypoint-initdb.d/
RUN chmod a+r /docker-entrypoint-initdb.d/*

And then you will have to execute conf.sql manually in already-existing databases. Since configuration is stored in the volume, it will survive rebuilds.


Another alternative is to pass -c flag as many times as you wish:

docker container run -d postgres -c max_connections=6 -c log_lock_waits=on

This way you don't need to build a new image, and you don't need to care about already-existing or not databases; all will be affected.

403 Forbidden error when making an ajax Post request in Django framework

Another approach is to add X-CSRFTOKEN header with the "{{ csrf_token }}" value like in the following example:

$.ajax({
            url: "{% url 'register_lowresistancetyres' %}",
            type: "POST",
            headers: {//<==
                        "X-CSRFTOKEN": "{{ csrf_token }}"//<==
                },
            data: $(example_form).serialize(),
            success: function(data) {
                //Success code
            },
            error: function () {
                //Error code
            }
        });

Accessing the logged-in user in a template

{{ app.user.username|default('') }}

Just present login username for example, filter function default('') should be nice when user is NOT login by just avoid annoying error message.

Linux delete file with size 0

You can use the command find to do this. We can match files with -type f, and match empty files using -size 0. Then we can delete the matches with -delete.

find . -type f -size 0 -delete

Submit HTML form on self page

You can do it using the same page on the action attribute: action='<yourpage>'

Difference between no-cache and must-revalidate

With Jeffrey Fox's interpretation about no-cache, i've tested under chrome 52.0.2743.116 m, the result shows that no-cache has the same behavior as must-revalidate, they all will NOT use local cache when server is unreachable, and, they all will use cache while tap browser's Back/Forward button when server is unreachable. As above, i think max-age=0, must-revalidate is identical to no-cache, at least in implementation.

Subset a dataframe by multiple factor levels

Here's another:

data[data$Code == "A" | data$Code == "B", ]

It's also worth mentioning that the subsetting factor doesn't have to be part of the data frame if it matches the data frame rows in length and order. In this case we made our data frame from this factor anyway. So,

data[Code == "A" | Code == "B", ]

also works, which is one of the really useful things about R.

Add colorbar to existing axis

The colorbar has to have its own axes. However, you can create an axes that overlaps with the previous one. Then use the cax kwarg to tell fig.colorbar to use the new axes.

For example:

import numpy as np
import matplotlib.pyplot as plt

data = np.arange(100, 0, -1).reshape(10, 10)

fig, ax = plt.subplots()
cax = fig.add_axes([0.27, 0.8, 0.5, 0.05])

im = ax.imshow(data, cmap='gist_earth')
fig.colorbar(im, cax=cax, orientation='horizontal')
plt.show()

enter image description here

Reading in a JSON File Using Swift

This worked great with me

func readjson(fileName: String) -> NSData{

    let path = NSBundle.mainBundle().pathForResource(fileName, ofType: "json")
    let jsonData = NSData(contentsOfMappedFile: path!)

    return jsonData!
}

Check if value already exists within list of dictionaries?

Following works out for me.

    #!/usr/bin/env python
    a = [{ 'main_color': 'red', 'second_color':'blue'},
    { 'main_color': 'yellow', 'second_color':'green'},
    { 'main_color': 'yellow', 'second_color':'blue'}]

    found_event = next(
            filter(
                lambda x: x['main_color'] == 'red',
                a
            ),
      #return this dict when not found
            dict(
                name='red',
                value='{}'
            )
        )

    if found_event:
        print(found_event)

    $python  /tmp/x
    {'main_color': 'red', 'second_color': 'blue'}

Understanding ibeacon distancing

It's possible, but it depends on the power output of the beacon you're receiving, other rf sources nearby, obstacles and other environmental factors. Best thing to do is try it out in the environment you're interested in.

"Multiple definition", "first defined here" errors

You should not include commands.c in your header file. In general, you should not include .c files. Rather, commands.c should include commands.h. As defined here, the C preprocessor is inserting the contents of commands.c into commands.h where the include is. You end up with two definitions of f123 in commands.h.

commands.h

#ifndef COMMANDS_H_
#define COMMANDS_H_

void f123();

#endif

commands.c

#include "commands.h"

void f123()
{
    /* code */
}

C++: Print out enum value as text

You could use a stl map container....

typedef map<Errors, string> ErrorMap;

ErrorMap m;
m.insert(ErrorMap::value_type(ErrorA, "ErrorA"));
m.insert(ErrorMap::value_type(ErrorB, "ErrorB"));
m.insert(ErrorMap::value_type(ErrorC, "ErrorC"));

Errors error = ErrorA;

cout << m[error] << endl;

When to use self over $this?

self (not $self) refers to the type of class, where as $this refers to the current instance of the class. self is for use in static member functions to allow you to access static member variables. $this is used in non-static member functions, and is a reference to the instance of the class on which the member function was called.

Because this is an object, you use it like: $this->member

Because self is not an object, it's basically a type that automatically refers to the current class, you use it like: self::member

How do you access the element HTML from within an Angular attribute directive?

This is because the content of

<p myHighlight>Highlight me!</p>

has not been rendered when the constructor of the HighlightDirective is called so there is no content yet.

If you implement the AfterContentInit hook you will get the element and its content.

import { Directive, ElementRef, AfterContentInit } from '@angular/core';

@Directive({ selector: '[myHighlight]' })

export class HighlightDirective {

    constructor(private el: ElementRef) {
        //el.nativeElement.style.backgroundColor = 'yellow';
    }

    ngAfterContentInit(){
        //you can get to the element content here 
        //this.el.nativeElement
    }
}

Python exit commands - why so many and when should each be used?

Different Means of Exiting

os._exit():

  • Exit the process without calling the cleanup handlers.

exit(0):

  • a clean exit without any errors / problems.

exit(1):

  • There was some issue / error / problem and that is why the program is exiting.

sys.exit():

  • When the system and python shuts down; it means less memory is being used after the program is run.

quit():

  • Closes the python file.

Summary

Basically they all do the same thing, however, it also depends on what you are doing it for.

I don't think you left anything out and I would recommend getting used to quit() or exit().

You would use sys.exit() and os._exit() mainly if you are using big files or are using python to control terminal.

Otherwise mainly use exit() or quit().

Refused to display 'url' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'

This happens because of your application does not allow to append iframe from origin other than your application domain.

If your application have web.config then add the following tag in web.config

<system.webServer>
    <httpProtocol>
        <customHeaders>
            <add name="X-Frame-Options" value="ALLOW" />
        </customHeaders>
    </httpProtocol>
</system.webServer>

This will allow application to append iframe from other origin also. You can also use the following value for X-Frame-Option

X-FRAME-OPTIONS: ALLOW-FROM https://example.com/ 

Oracle SQL - DATE greater than statement

you have to use the To_Date() function to convert the string to date ! http://www.techonthenet.com/oracle/functions/to_date.php

Decrementing for loops

Check out the range documentation, you have to define a negative step:

>>> range(10, 0, -1)
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]

What is the difference between conversion specifiers %i and %d in formatted IO functions (*printf / *scanf)

They are the same when used for output, e.g. with printf.

However, these are different when used as input specifier e.g. with scanf, where %d scans an integer as a signed decimal number, but %i defaults to decimal but also allows hexadecimal (if preceded by 0x) and octal (if preceded by 0).

So 033 would be 27 with %i but 33 with %d.

Maximum and minimum values in a textbox

Set Attributes in CodeBehind

textWeight.Attributes.Add("minimum", minValue.ToString());
textWeight.Attributes.Add("maximum", maxValue.ToString());

Result:

<input type="text" minimum="0" maximum="100" id="textWeight" value="2" name="textWeight">

By jQuery

    jQuery(document).ready(function () {

        var textWeight = $("input[type='text']#textWeight");

        textWeight.change(function () {

              var min = textWeight.attr("minimum");

              var max= textWeight.attr("maximum");

              var value = textWeight.val();

              if(val < min || val > max)
              {
                    alert("Your Message");

                    textWeight.val(min);
              }

        });
    });

Apply multiple functions to multiple groupby columns

New in version 0.25.0.

To support column-specific aggregation with control over the output column names, pandas accepts the special syntax in GroupBy.agg(), known as “named aggregation”, where

  • The keywords are the output column names
  • The values are tuples whose first element is the column to select and the second element is the aggregation to apply to that column. Pandas provides the pandas.NamedAgg namedtuple with the fields ['column', 'aggfunc'] to make it clearer what the arguments are. As usual, the aggregation can be a callable or a string alias.
    In [79]: animals = pd.DataFrame({'kind': ['cat', 'dog', 'cat', 'dog'],
       ....:                         'height': [9.1, 6.0, 9.5, 34.0],
       ....:                         'weight': [7.9, 7.5, 9.9, 198.0]})
       ....: 

    In [80]: animals
    Out[80]: 
      kind  height  weight
    0  cat     9.1     7.9
    1  dog     6.0     7.5
    2  cat     9.5     9.9
    3  dog    34.0   198.0

    In [81]: animals.groupby("kind").agg(
       ....:     min_height=pd.NamedAgg(column='height', aggfunc='min'),
       ....:     max_height=pd.NamedAgg(column='height', aggfunc='max'),
       ....:     average_weight=pd.NamedAgg(column='weight', aggfunc=np.mean),
       ....: )
       ....: 
    Out[81]: 
          min_height  max_height  average_weight
    kind                                        
    cat          9.1         9.5            8.90
    dog          6.0        34.0          102.75

pandas.NamedAgg is just a namedtuple. Plain tuples are allowed as well.

    In [82]: animals.groupby("kind").agg(
       ....:     min_height=('height', 'min'),
       ....:     max_height=('height', 'max'),
       ....:     average_weight=('weight', np.mean),
       ....: )
       ....: 
    Out[82]: 
          min_height  max_height  average_weight
    kind                                        
    cat          9.1         9.5            8.90
    dog          6.0        34.0          102.75

Additional keyword arguments are not passed through to the aggregation functions. Only pairs of (column, aggfunc) should be passed as **kwargs. If your aggregation functions requires additional arguments, partially apply them with functools.partial().

Named aggregation is also valid for Series groupby aggregations. In this case there’s no column selection, so the values are just the functions.

    In [84]: animals.groupby("kind").height.agg(
       ....:     min_height='min',
       ....:     max_height='max',
       ....: )
       ....: 
    Out[84]: 
          min_height  max_height
    kind                        
    cat          9.1         9.5
    dog          6.0        34.0

2D array values C++

Just want to point out you do not need to specify all dimensions of the array.

The leftmost dimension can be 'guessed' by the compiler.

#include <stdio.h>
int main(void) {
  int arr[][5] = {{1,2,3,4,5}, {5,6,7,8,9}, {6,5,4,3,2}};
  printf("sizeof arr is %d bytes\n", (int)sizeof arr);
  printf("number of elements: %d\n", (int)(sizeof arr/sizeof arr[0]));
  return 0;
}

How to Pass Parameters to Activator.CreateInstance<T>()

As an alternative to Activator.CreateInstance, FastObjectFactory in the linked url preforms better than Activator (as of .NET 4.0 and significantly better than .NET 3.5. No tests/stats done with .NET 4.5). See StackOverflow post for stats, info and code:

How to pass ctor args in Activator.CreateInstance or use IL?

How to check if a windows form is already open, and close it if it is?

* Hope This will work for u

System.Windows.Forms.Form f1 = System.Windows.Forms.Application.OpenForms["Order"];
if(((Order)f1)!=null)
{
//open Form
}
else
{
//not open
}

Recommended way to get hostname in Java

hostName == null;
Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
{
    while (interfaces.hasMoreElements()) {
        NetworkInterface nic = interfaces.nextElement();
        Enumeration<InetAddress> addresses = nic.getInetAddresses();
        while (hostName == null && addresses.hasMoreElements()) {
            InetAddress address = addresses.nextElement();
            if (!address.isLoopbackAddress()) {
                hostName = address.getHostName();
            }
        }
    }
}

"query function not defined for Select2 undefined error"

Also got the same error when using ajax.

If you're using ajax to render forms with select2, the input_html class must be different from those NOT rendered using ajax. Not quite sure why it works this way though.

How do you find the sum of all the numbers in an array in Java?

class Addition {

     public static void main() {
          int arr[]={5,10,15,20,25,30};         //Declaration and Initialization of an Array
          int sum=0;                            //To find the sum of array elements
          for(int i:arr) {
              sum += i;
          }
          System.out.println("The sum is :"+sum);//To display the sum 
     }
} 

jQuery Remove string from string

Pretty sure nobody answer your question to your exact terms, you want it for dynamic text

var newString = myString.substring( myString.indexOf( "," ) +1, myString.length );

It takes a substring from the first comma, to the end

"inappropriate ioctl for device"

I got the error Can't open file for reading. Inappropriate ioctl for device recently when I migrated an old UB2K forum with a DBM file-based database to a new host. Apparently there are multiple, incompatible implementations of DBM. I had a backup of the database, so I was able to load that, but it seems there are other options e.g. moving a perl script/dbm to a new server, and shifting out of dbm?.

How do negative margins in CSS work and why is (margin-top:-5 != margin-bottom:5)?

Margin is the spacing outside your element, just as padding is the spacing inside your element.

Setting the bottom margin indicates what distance you want below the current block. Setting a negative top margin indicates that you want negative spacing above your block. Negative spacing may in itself be a confusing concept, but just the way positive top margin pushes content down, a negative top margin pulls content up.

How to automatically select all text on focus in WPF TextBox?

Taken from here:

Register global event handler in App.xaml.cs file:

protected override void OnStartup(StartupEventArgs e)
{
    EventManager.RegisterClassHandler(typeof(TextBox),TextBox.GotFocusEvent,
    new RoutedEventHandler(TextBox_GotFocus));

    base.OnStartup(e);
}

Then the handler is as simple as:

private void TextBox_GotFocus(object sender, RoutedEventArgs e)
{
    (sender as TextBox).SelectAll();
}

Room persistance library. Delete all

Here is how I have done it in Kotlin.

  1. Inject room db in the activity using DI (Koin).

     private val appDB: AppDB by inject()
    
  2. Then you can simply call clearAllTables()

private fun clearRoomDB() {
    GlobalScope.launch {
        appDB.clearAllTables()
        preferences.put(PreferenceConstants.IS_UPLOADCATEGORIES_SAVED_TO_DB, false)
        preferences.put(PreferenceConstants.IS_MEMBERHANDBOOK_SAVED_TO_DB, false)
    }
}

How to change facebook login button with my custom image

Found a site on google explaining some changes, according to the author of the page fb does not allow custom buttons. Heres the website.

Unfortunately, it’s against Facebook’s developer policies, which state:

You must not circumvent our intended limitations on core Facebook features.

The Facebook Connect button is intended to be rendered in FBML, which means it’s only meant to look the way Facebook lets it.

How do I pass along variables with XMLHTTPRequest

How about?

function callHttpService(url, params){
  // Assume params contains key/value request params
  let queryStrings = '';

  for(let key in params){
      queryStrings += `${key}=${params[key]}&`
    } 
 const fullUrl = `${url}?queryStrings`

  //make http request with fullUrl
}

Get the latest date from grouped MySQL data

Are you looking for the max date for each model?

SELECT model, max(date) FROM doc
GROUP BY model

If you're looking for all models matching the max date of the entire table...

SELECT model, date FROM doc
WHERE date IN (SELECT max(date) FROM doc)

[--- Added ---]

For those who want to display details from every record matching the latest date within each model group (not summary data, as asked for in the OP):

SELECT d.model, d.date, d.color, d.etc FROM doc d
WHERE d.date IN (SELECT max(d2.date) FROM doc d2 WHERE d2.model=d.model)

MySQL 8.0 and newer supports the OVER clause, producing the same results a bit faster for larger data sets.

SELECT model, date, color, etc FROM (SELECT model, date, color, etc, 
  max(date) OVER (PARTITION BY model) max_date FROM doc) predoc 
WHERE date=max_date;

Change the "From:" address in Unix "mail"

mail -s "$(echo -e "This is the subject\nFrom: Paula <[email protected]>\n
Reply-to: [email protected]\nContent-Type: text/html\n")" 
[email protected] < htmlFileMessage.txt

the above is my solution....any extra headers can be added just after the from and before the reply to...just make sure you know your headers syntax before adding them....this worked perfectly for me.

How to redirect output of an entire shell script within the script itself?

Typically we would place one of these at or near the top of the script. Scripts that parse their command lines would do the redirection after parsing.

Send stdout to a file

exec > file

with stderr

exec > file                                                                      
exec 2>&1

append both stdout and stderr to file

exec >> file
exec 2>&1

As Jonathan Leffler mentioned in his comment:

exec has two separate jobs. The first one is to replace the currently executing shell (script) with a new program. The other is changing the I/O redirections in the current shell. This is distinguished by having no argument to exec.

Formatting floats without trailing zeros

You could use %g to achieve this:

'%g'%(3.140)

or, with Python = 2.6:

'{0:g}'.format(3.140)

From the docs for format: g causes (among other things)

insignificant trailing zeros [to be] removed from the significand, and the decimal point is also removed if there are no remaining digits following it.

Java method to swap primitives

AFAIS, no one mentions of atomic reference.

Integer

public void swap(AtomicInteger a, AtomicInteger b){
    a.set(b.getAndSet(a.get()));
}

String

public void swap(AtomicReference<String> a, AtomicReference<String> b){
    a.set(b.getAndSet(a.get()));
}

What is the advantage of using heredoc in PHP?

I don't know if I would say heredoc is laziness. One can say that doing anything is laziness, as there are always more cumbersome ways to do anything.

For example, in certain situations you may want to output text, with embedded variables without having to fetch from a file and run a template replace. Heredoc allows you to forgo having to escape quotes, so the text you see is the text you output. Clearly there are some negatives, for example, you can't indent your heredoc, and that can get frustrating in certain situation, especially if your a stickler for unified syntax, which I am.

When to use window.opener / window.parent / window.top

when you are dealing with popups window.opener plays an important role, because we have to deal with fields of parent page as well as child page, when we have to use values on parent page we can use window.opener or we want some data on the child window or popup window at the time of loading then again we can set the values using window.opener

What's the difference between %s and %d in Python string formatting?

In case you would like to avoid %s or %d then..

name = 'marcog'
number = 42
print ('my name is',name,'and my age is:', number)

Output:

my name is marcog and my name is 42

Sort columns of a dataframe by column name

Here's the obligatory dplyr answer in case somebody wants to do this with the pipe.

test %>% 
    select(sort(names(.)))

zsh compinit: insecure directories

Send a y character to the input stream of the script using compinit, in order to automatically answer the Ignore insecure directories and files and continue [y] or abort compinit [n]? question

echo "y" > source <GOOGLECLOUDSDK>/completion.zsh.inc

The solution is useful when

  • you can't make ownership/access changes to the folders
  • when you can't use the -u option to remove the warning (probably because you don't explicitly call 'compinit' yourself, but it's called by a script you call)

Remark: It doesn't fix the problem and only hides the warning (as opposed to others answers here which involve removing 'group write access' or 'change ownership to root').

Checking session if empty or not

Use this if the session variable emp_num will store a string:

 if (!string.IsNullOrEmpty(Session["emp_num"] as string))
 {
                //The code
 }

If it doesn't store a string, but some other type, you should just check for null before accessing the value, as in your second example.

PHP list of specific files in a directory

You'll be wanting to use glob()

Example:

$files = glob('/path/to/dir/*.xml');

How can I close a window with Javascript on Mozilla Firefox 3?

This code works for both IE 7 and the latest version of Mozilla although the default setting in mozilla doesnt allow to close a window through javascript.

Here is the code:

function F11() { window.open('','_parent',''); window.open("login.aspx", "", "channelmode"); window.close(); }

To change the default setting :

1.type"about:config " in your firefox address bar and enter;

2.make sure your "dom.allow_scripts_to_close_windows" is true

"No rule to make target 'install'"... But Makefile exists

I also came across the same error. Here is the fix: If you are using Cmake-GUI:

  1. Clean the cache of the loaded libraries in Cmake-GUI File menu.
  2. Configure the libraries.
  3. Generate the Unix file.

If you missed the 3rd step:

*** No rule to make target `install'. Stop.

error will occur.

How can I convert this foreach code to Parallel.ForEach?

string[] lines = File.ReadAllLines(txtProxyListPath.Text);

// No need for the list
// List<string> list_lines = new List<string>(lines); 

Parallel.ForEach(lines, line =>
{
    //My Stuff
});

This will cause the lines to be parsed in parallel, within the loop. If you want a more detailed, less "reference oriented" introduction to the Parallel class, I wrote a series on the TPL which includes a section on Parallel.ForEach.

How to add values in a variable in Unix shell scripting?

read num1
read num2
sum=`expr $num1 + $num2`
echo $sum

Could not install packages due to an EnvironmentError: [Errno 13]

I have anaconda installed for Python 3. I also have Python2 in my mac.

python --version

gives me

Python 3.7.3

python2.7 --version

gives me

Python 2.7.10

I wanted to install pyspark package in python2, given that it was already installed in python3.

python2.7 -m pip install pyspark

gives me an error

Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/pyspark' Consider using the --user option or check the permissions.

The below command solved it. Thank god I didn't have to do any config changes.

python2.7 -m pip install pyspark --user

Collecting pyspark Requirement already satisfied: py4j==0.10.7 in /Library/Python/2.7/site-packages (from pyspark) (0.10.7) Installing collected packages: pyspark Successfully installed pyspark-2.4.4 You are using pip version 18.1, however version 19.3.1 is available. You should consider upgrading via the 'pip install --upgrade pip' command.

How to sort a HashSet?

you can do this in the following ways:

Method 1:

  1. Create a list and store all the hashset values into it
  2. sort the list using Collections.sort()
  3. Store the list back into LinkedHashSet as it preserves the insertion order

Method 2:

  • Create a treeSet and store all the values into it.

Method 2 is more preferable because the other method consumes lot of time to transfer data back and forth between hashset and list.

How do I read a large csv file with pandas?

The above answer is already satisfying the topic. Anyway, if you need all the data in memory - have a look at bcolz. Its compressing the data in memory. I have had really good experience with it. But its missing a lot of pandas features

Edit: I got compression rates at around 1/10 or orig size i think, of course depending of the kind of data. Important features missing were aggregates.

How do I change column default value in PostgreSQL?

'SET' is forgotten

ALTER TABLE ONLY users ALTER COLUMN lang SET DEFAULT 'en_GB';

caching JavaScript files

or in the .htaccess file

AddOutputFilter DEFLATE css js
ExpiresActive On
ExpiresByType application/x-javascript A2592000

How to sort a list of objects based on an attribute of the objects?

from operator import attrgetter
ut.sort(key = attrgetter('count'), reverse = True)

Debug JavaScript in Eclipse

MyEclipse (eclipse based, subscription required) and Webclipse (an eclipse plug-in, currently free), from my company, Genuitec, have newly engineered (as of 2015) JavaScript debugging built in:

enter image description here

You can debug both generic web applications and Node.js files.

How to show loading spinner in jQuery?

Use the loading plugin: http://plugins.jquery.com/project/loading

$.loading.onAjax({img:'loading.gif'});

Datatables warning(table id = 'example'): cannot reinitialise data table

Search in your code maybe you have initialized dataTable twice in your code. You shold have like this code:

$('#example').dataTable( {paging: false} );

Only one time in your code.

Java compile error: "reached end of file while parsing }"

It happens when you don't properly close the code block:

if (condition){
  // your code goes here*
  { // This doesn't close the code block

Correct way:

if (condition){
  // your code goes here
} // Close the code block

What is a word boundary in regex, does \b match hyphen '-'?

Word boundary \b is used where one word should be a word character and another one a non-word character. Regular Expression for negative number should be

--?\b\d+\b

check working DEMO

Is using 'var' to declare variables optional?

Nope, they are not equivalent.

With myObj = 1; you are using a global variable.

The latter declaration create a variable local to the scope you are using.

Try the following code to understand the differences:

external = 5;
function firsttry() {
  var external = 6;
  alert("first Try: " + external);
}

function secondtry() {
  external = 7;
  alert("second Try: " + external);
}

alert(external); // Prints 5
firsttry(); // Prints 6
alert(external); // Prints 5
secondtry(); // Prints 7
alert(external); // Prints 7

The second function alters the value of the global variable "external", but the first function doesn't.

How to fix syntax error, unexpected T_IF error in php?

Here is the issue

  $total_result = $result->num_rows;

try this

<?php
if ($result = $mysqli->query("SELECT * FROM players ORDER BY id"))
{
    if ($result->num_rows > 0)
    {
        $total_result = $result->num_rows;
        $total_pages = ceil($total_result / $per_page);

        if(isset($_GET['page']) && is_numeric($_GET['page']))
        {
            $show_page = $_GET['page'];

            if ($show_page > 0 && $show_page <= $total_pages)
            {
                $start = ($show_page - 1) * $per_page;
                $end = $start + $per_page;
            }
            else
            {
                $start = 0;
                $end = $per_page;
            }               

        }
        else
        {
            $start = 0;
            $end = $per_page;
        }


        //display paginations
        echo "<p> View pages: ";
        for ($i=1; $i < $total_pages; $i++)
        { 
            if (isset($_GET['page']) && $_GET['page'] == $i)
            {
                echo  $i . " ";
            }
            else
            {
                echo "<a href='view-pag.php?$i'>" . $i . "</a> | ";
            }

        }
        echo "</p>";

    }
    else
    {
        echo "No result to display.";
    }

}
else
{
    echo "Error: " . $mysqli->error;
}


?>

Java TreeMap Comparator

The comparator should be only for the key, not for the whole entry. It sorts the entries based on the keys.

You should change it to something as follows

SortedMap<String, Double> myMap = 
    new TreeMap<String, Double>(new Comparator<String>()
    {
        public int compare(String o1, String o2)
        {
            return o1.compareTo(o2);
        } 
});

Update

You can do something as follows (create a list of entries in the map and sort the list base on value, but note this not going to sort the map itself) -

List<Map.Entry<String, Double>> entryList = new ArrayList<Map.Entry<String, Double>>(myMap.entrySet());
    Collections.sort(entryList, new Comparator<Map.Entry<String, Double>>() {
        @Override
        public int compare(Entry<String, Double> o1, Entry<String, Double> o2) {
            return o1.getValue().compareTo(o2.getValue());
        }
    });

How to add elements of a Java8 stream into an existing List

Erik Allik already gave very good reasons, why you will most likely not want to collect elements of a stream into an existing List.

Anyway, you can use the following one-liner, if you really need this functionality.

But as Stuart Marks explains in his answer, you should never do this, if the streams might be parallel streams - use at your own risk...

list.stream().collect(Collectors.toCollection(() -> myExistingList));

Execute write on doc: It isn't possible to write into a document from an asynchronously-loaded external script unless it is explicitly opened.

A bit late to the party, but Krux has created a script for this, called Postscribe. We were able to use this to get past this issue.

Decompile an APK, modify it and then recompile it

This is a way:

  1. Using apktool to decode:

     $ apktool d -f {apkfile} -o {output folder}
    
  2. Next, using JADX (at github.com/skylot/jadx)

     $ jadx -d {output folder} {apkfile}
    

2 tools extract and decompiler to same output folder.

Easy way: Using Online APK Decompiler

What are the differences between using the terminal on a mac vs linux?

If you did a new or clean install of OS X version 10.3 or more recent, the default user terminal shell is bash.

Bash is essentially an enhanced and GNU freeware version of the original Bourne shell, sh. If you have previous experience with bash (often the default on GNU/Linux installations), this makes the OS X command-line experience familiar, otherwise consider switching your shell either to tcsh or to zsh, as some find these more user-friendly.

If you upgraded from or use OS X version 10.2.x, 10.1.x or 10.0.x, the default user shell is tcsh, an enhanced version of csh('c-shell'). Early implementations were a bit buggy and the programming syntax a bit weird so it developed a bad rap.

There are still some fundamental differences between mac and linux as Gordon Davisson so aptly lists, for example no useradd on Mac and ifconfig works differently.

The following table is useful for knowing the various unix shells.

sh      The original Bourne shell   Present on every unix system 
ksh     Original Korn shell         Richer shell programming environment than sh 
csh     Original C-shell            C-like syntax; early versions buggy 
tcsh    Enhanced C-shell            User-friendly and less buggy csh implementation 
bash    GNU Bourne-again shell      Enhanced and free sh implementation 
zsh     Z shell                     Enhanced, user-friendly ksh-like shell

You may also find these guides helpful:

http://homepage.mac.com/rgriff/files/TerminalBasics.pdf

http://guides.macrumors.com/Terminal
http://www.ofb.biz/safari/article/476.html

On a final note, I am on Linux (Ubuntu 11) and Mac osX so I use bash and the thing I like the most is customizing the .bashrc (source'd from .bash_profile on OSX) file with aliases, some examples below. I now placed all my aliases in a separate .bash_aliases file and include it with:

if [ -f ~/.bash_aliases ]; then
    . ~/.bash_aliases
fi

in the .bashrc or .bash_profile file.

Note that this is an example of a mac-linux difference because on a Mac you can't have the --color=auto. The first time I did this (without knowing) I redefined ls to be invalid which was a bit alarming until I removed --auto-color !

You may also find https://unix.stackexchange.com/q/127799/10043 useful

# ~/.bash_aliases
# ls variants
#alias l='ls -CF' 
alias la='ls -A' 
alias l='ls -alFtr' 
alias lsd='ls -d .*' 
# Various
alias h='history | tail'
alias hg='history | grep'
alias mv='mv -i' 
alias zap='rm -i'
# One letter quickies:
alias p='pwd'
alias x='exit'
alias {ack,ak}='ack-grep'
# Directories
alias s='cd ..'
alias play='cd ~/play/'
# Rails
alias src='script/rails console'
alias srs='script/rails server'
alias raked='rake db:drop db:create db:migrate db:seed' 
alias rvm-restart='source '\''/home/durrantm/.rvm/scripts/rvm'\'''
alias rrg='rake routes | grep '
alias rspecd='rspec --drb '
#
# DropBox - syncd
WORKBASE="~/Dropbox/97_2012/work"
alias work="cd $WORKBASE"
alias code="cd $WORKBASE/ror/code"
#
# DropNot - NOT syncd !
WORKBASE_GIT="~/Dropnot"
alias {dropnot,not}="cd $WORKBASE_GIT"
alias {webs,ww}="cd $WORKBASE_GIT/webs"
alias {setups,docs}="cd $WORKBASE_GIT/setups_and_docs"
alias {linker,lnk}="cd $WORKBASE_GIT/webs/rails_v3/linker"
#
# git
alias {gsta,gst}='git status' 
# Warning: gst conflicts with gnu-smalltalk (when used).
alias {gbra,gb}='git branch'
alias {gco,go}='git checkout'
alias {gcob,gob}='git checkout -b '
alias {gadd,ga}='git add '
alias {gcom,gc}='git commit'
alias {gpul,gl}='git pull '
alias {gpus,gh}='git push '
alias glom='git pull origin master'
alias ghom='git push origin master'
alias gg='git grep '
#
# vim
alias v='vim'
#
# tmux
alias {ton,tn}='tmux set -g mode-mouse on'
alias {tof,tf}='tmux set -g mode-mouse off'
#
# dmc
alias {dmc,dm}='cd ~/Dropnot/webs/rails_v3/dmc/'
alias wf='cd ~/Dropnot/webs/rails_v3/dmc/dmWorkflow'
alias ws='cd ~/Dropnot/webs/rails_v3/dmc/dmStaffing'

Excel 2007: How to display mm:ss format not as a DateTime (e.g. 73:07)?

enter the values as 0:mm:ss and format as [m]:ss

as this is now in the mins & seconds, simple arithmetic will allow you to calculate your statistics

What is the difference between JavaScript and jQuery?

Javascript is a programming language whereas jQuery is a library to help make writing in javascript easier. It's particularly useful for simply traversing the DOM in an HTML page.

What is the convention for word separator in Java package names?

Concatenation of words in the package name is something most developers don't do.

You can use something like.

com.stackoverflow.mypackage

Refer JLS Name Declaration

How to restart a node.js server

In this case you are restarting your node.js server often because it's in active development and you are making changes all the time. There is a great hot reload script that will handle this for you by watching all your .js files and restarting your node.js server if any of those files have changed. Just the ticket for rapid development and test.

The script and explanation on how to use it are at here at Draco Blue.

Best way to reverse a string

string A = null;
//a now is reversed and you can use it
A = SimulateStrReverse.StrReverse("your string");

public static class SimulateStrReverse
{
    public static string StrReverse(string expression)
    {
        if (string.IsNullOrEmpty(expression))
            return string.Empty;

        string reversedString = string.Empty;
        for (int charIndex = expression.Length - 1; charIndex >= 0; charIndex--)
        {
            reversedString += expression[charIndex];
        }
        return reversedString;
    }
}

Angularjs loading screen on ajax request

Here's an example. It uses the simple ng-show method with a bool.

HTML

<div ng-show="loading" class="loading"><img src="...">LOADING...</div>
<div ng-repeat="car in cars">
  <li>{{car.name}}</li>
</div>
<button ng-click="clickMe()" class="btn btn-primary">CLICK ME</button>

ANGULARJS

  $scope.clickMe = function() {
    $scope.loading = true;
    $http.get('test.json')
      .success(function(data) {
        $scope.cars = data[0].cars;
        $scope.loading = false;
    });
  }

Of course you can move the loading box html code into a directive, then use $watch on $scope.loading. In which case:

HTML:

<loading></loading>

ANGULARJS DIRECTIVE:

  .directive('loading', function () {
      return {
        restrict: 'E',
        replace:true,
        template: '<div class="loading"><img src="..."/>LOADING...</div>',
        link: function (scope, element, attr) {
              scope.$watch('loading', function (val) {
                  if (val)
                      $(element).show();
                  else
                      $(element).hide();
              });
        }
      }
  })

PLUNK: http://plnkr.co/edit/AI1z21?p=preview

How do I use an image as a submit button?

Just remove the border and add a background image in css

Example:

_x000D_
_x000D_
$("#form").on('submit', function() {_x000D_
   alert($("#submit-icon").val());_x000D_
});
_x000D_
#submit-icon {_x000D_
  background-image: url("https://pixabay.com/static/uploads/photo/2016/10/18/21/22/california-1751455__340.jpg"); /* Change url to wanted image */_x000D_
  background-size: cover;_x000D_
  border: none;_x000D_
  width: 32px;_x000D_
  height: 32px;_x000D_
  cursor: pointer;_x000D_
  color: transparent;_x000D_
}
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>_x000D_
<form id="form">_x000D_
  <input type="submit" id="submit-icon" value="test">_x000D_
</form>
_x000D_
_x000D_
_x000D_

Add vertical whitespace using Twitter Bootstrap?

Sorry to dig an old grave here, but why not just do this?

<div class="form-group">
    &nbsp;
</div>

It will add a space the height of a normal form element.

It seems about 1 line on a form is roughly 50px (47px on my element I just inspected). This is a horizontal form, with label on left 2col and input on right 10col. So your pixels may vary.

Since mine is basically 50px, I would create a spacer of 50px tall with no margins or padding;

.spacer { margin:0; padding:0; height:50px; }
<div class="spacer"></div>

Attaching a Sass/SCSS to HTML docs

You can not "attach" a SASS/SCSS file to an HTML document.

SASS/SCSS is a CSS preprocessor that runs on the server and compiles to CSS code that your browser understands.

There are client-side alternatives to SASS that can be compiled in the browser using javascript such as LESS CSS, though I advise you compile to CSS for production use.

It's as simple as adding 2 lines of code to your HTML file.

<link rel="stylesheet/less" type="text/css" href="styles.less" />
<script src="less.js" type="text/javascript"></script>

How to declare a variable in a PostgreSQL query

Using a Temp Table outside of pl/PgSQL

Outside of using pl/pgsql or other pl/* language as suggested, this is the only other possibility I could think of.

begin;
select 5::int as var into temp table myvar;
select *
  from somewhere s, myvar v
 where s.something = v.var;
commit;

sql how to cast a select query

You just CAST() this way

SELECT cast(yourNumber as varchar(10))
FROM yourTable

Then if you want to JOIN based on it, you can use:

SELECT *
FROM yourTable t1
INNER JOIN yourOtherTable t2
    on cast(t1.yourNumber as varchar(10)) = t2.yourString

How to generate the "create table" sql statement for an existing table in postgreSQL

Like the other answers mentioned, there is no built in function that does this.

Here is a function that attempts to get all of the information that would be needed to replicate the table - or to compare deployed and checked in ddl.

This function outputs:

  • columns (w/ precision, null/not-null, default value)
  • constraints
  • indexes

CREATE OR REPLACE FUNCTION public.show_create_table(
  in_schema_name varchar,
  in_table_name varchar
)
RETURNS text
LANGUAGE plpgsql VOLATILE
AS
$$
  DECLARE
    -- the ddl we're building
    v_table_ddl text;

    -- data about the target table
    v_table_oid int;

    -- records for looping
    v_column_record record;
    v_constraint_record record;
    v_index_record record;
  BEGIN
    -- grab the oid of the table; https://www.postgresql.org/docs/8.3/catalog-pg-class.html
    SELECT c.oid INTO v_table_oid
    FROM pg_catalog.pg_class c
    LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
    WHERE 1=1
      AND c.relkind = 'r' -- r = ordinary table; https://www.postgresql.org/docs/9.3/catalog-pg-class.html
      AND c.relname = in_table_name -- the table name
      AND n.nspname = in_schema_name; -- the schema

    -- throw an error if table was not found
    IF (v_table_oid IS NULL) THEN
      RAISE EXCEPTION 'table does not exist';
    END IF;

    -- start the create definition
    v_table_ddl := 'CREATE TABLE ' || in_schema_name || '.' || in_table_name || ' (' || E'\n';

    -- define all of the columns in the table; https://stackoverflow.com/a/8153081/3068233
    FOR v_column_record IN
      SELECT
        c.column_name,
        c.data_type,
        c.character_maximum_length,
        c.is_nullable,
        c.column_default
      FROM information_schema.columns c
      WHERE (table_schema, table_name) = (in_schema_name, in_table_name)
      ORDER BY ordinal_position
    LOOP
      v_table_ddl := v_table_ddl || '  ' -- note: two char spacer to start, to indent the column
        || v_column_record.column_name || ' '
        || v_column_record.data_type || CASE WHEN v_column_record.character_maximum_length IS NOT NULL THEN ('(' || v_column_record.character_maximum_length || ')') ELSE '' END || ' '
        || CASE WHEN v_column_record.is_nullable = 'NO' THEN 'NOT NULL' ELSE 'NULL' END
        || CASE WHEN v_column_record.column_default IS NOT null THEN (' DEFAULT ' || v_column_record.column_default) ELSE '' END
        || ',' || E'\n';
    END LOOP;

    -- define all the constraints in the; https://www.postgresql.org/docs/9.1/catalog-pg-constraint.html && https://dba.stackexchange.com/a/214877/75296
    FOR v_constraint_record IN
      SELECT
        con.conname as constraint_name,
        con.contype as constraint_type,
        CASE
          WHEN con.contype = 'p' THEN 1 -- primary key constraint
          WHEN con.contype = 'u' THEN 2 -- unique constraint
          WHEN con.contype = 'f' THEN 3 -- foreign key constraint
          WHEN con.contype = 'c' THEN 4
          ELSE 5
        END as type_rank,
        pg_get_constraintdef(con.oid) as constraint_definition
      FROM pg_catalog.pg_constraint con
      JOIN pg_catalog.pg_class rel ON rel.oid = con.conrelid
      JOIN pg_catalog.pg_namespace nsp ON nsp.oid = connamespace
      WHERE nsp.nspname = in_schema_name
      AND rel.relname = in_table_name
      ORDER BY type_rank
    LOOP
      v_table_ddl := v_table_ddl || '  ' -- note: two char spacer to start, to indent the column
        || 'CONSTRAINT' || ' '
        || v_constraint_record.constraint_name || ' '
        || v_constraint_record.constraint_definition
        || ',' || E'\n';
    END LOOP;

    -- drop the last comma before ending the create statement
    v_table_ddl = substr(v_table_ddl, 0, length(v_table_ddl) - 1) || E'\n';

    -- end the create definition
    v_table_ddl := v_table_ddl || ');' || E'\n';

    -- suffix create statement with all of the indexes on the table
    FOR v_index_record IN
      SELECT indexdef
      FROM pg_indexes
      WHERE (schemaname, tablename) = (in_schema_name, in_table_name)
    LOOP
      v_table_ddl := v_table_ddl
        || v_index_record.indexdef
        || ';' || E'\n';
    END LOOP;

    -- return the ddl
    RETURN v_table_ddl;
  END;
$$;

example

SELECT * FROM public.show_create_table('public', 'example_table');

produces

CREATE TABLE public.example_table (
  id bigint NOT NULL DEFAULT nextval('test_tb_for_show_create_on_id_seq'::regclass),
  name character varying(150) NULL,
  level character varying(50) NULL,
  description text NOT NULL DEFAULT 'hello there!'::text,
  CONSTRAINT test_tb_for_show_create_on_pkey PRIMARY KEY (id),
  CONSTRAINT test_tb_for_show_create_on_level_check CHECK (((level)::text = ANY ((ARRAY['info'::character varying, 'warn'::character varying, 'error'::character varying])::text[])))
);
CREATE UNIQUE INDEX test_tb_for_show_create_on_pkey ON public.test_tb_for_show_create_on USING btree (id);

Error:(9, 5) error: resource android:attr/dialogCornerRadius not found

In my case, I was getting this error in AndroidStudio 4.1.1 while updating compileSdkVersion to 29.

If you are having dependent project in build.gradle, All you need to do is Update same compileSdkVersion in dependent project's build.gradle as well.

Steps:

  1. Click on your app folder in Project view of AndroidStudio.
  2. Select Open Module Settings.
  3. In Project Structure >> Check how many modules are there?
  4. If there are more than one modules, you will have to update compileSdkVersion, buildToolsVersion & Project dependency as well.

That worked for me :)

Android Linear Layout - How to Keep Element At Bottom Of View?

Update: I still get upvotes on this question, which is still the accepted answer and which I think I answered poorly. In the spirit of making sure the best info is out there, I have decided to update this answer.

In modern Android I would use ConstraintLayout to do this. It is more performant and straightforward.

<ConstraintLayout>
   <View
      android:id="@+id/view1"
      ...other attributes elided... />
   <View
      android:id="@id/view2"        
      app:layout_constraintTop_toBottomOf="@id/view1" />
      ...other attributes elided... />

   ...etc for other views that should be aligned top to bottom...

   <TextView
    app:layout_constraintBottom_toBottomOf="parent" />

If you don't want to use a ConstraintLayout, using a LinearLayout with an expanding view is a straightforward and great way to handle taking up the extra space (see the answer by @Matthew Wills). If you don't want to expand the background of any of the Views above the bottom view, you can add an invisible View to take up the space.

The answer I originally gave works but is inefficient. Inefficiency may not be a big deal for a single top level layout, but it would be a terrible implementation in a ListView or RecyclerView, and there just isn't any reason to do it since there are better ways to do it that are roughly the same level of effort and complexity if not simpler.

Take the TextView out of the LinearLayout, then put the LinearLayout and the TextView inside a RelativeLayout. Add the attribute android:layout_alignParentBottom="true" to the TextView. With all the namespace and other attributes except for the above attribute elided:

<RelativeLayout>
  <LinearLayout>
    <!-- All your other elements in here -->
  </LinearLayout>
  <TextView
    android:layout_alignParentBottom="true" />
</RelativeLayout>

AddTransient, AddScoped and AddSingleton Services Differences

After looking for an answer for this question I found a brilliant explanation with an example that I would like to share with you.

You can watch a video that demonstrate the differences HERE

In this example we have this given code:

public interface IEmployeeRepository
{
    IEnumerable<Employee> GetAllEmployees();
    Employee Add(Employee employee);
}

public class Employee
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class MockEmployeeRepository : IEmployeeRepository
{
    private List<Employee> _employeeList;

    public MockEmployeeRepository()
    {
        _employeeList = new List<Employee>()
    {
        new Employee() { Id = 1, Name = "Mary" },
        new Employee() { Id = 2, Name = "John" },
        new Employee() { Id = 3, Name = "Sam" },
    };
    }

    public Employee Add(Employee employee)
    {
        employee.Id = _employeeList.Max(e => e.Id) + 1;
        _employeeList.Add(employee);
        return employee;
    }

    public IEnumerable<Employee> GetAllEmployees()
    {
        return _employeeList;
    }
}

HomeController

public class HomeController : Controller
{
    private IEmployeeRepository _employeeRepository;

    public HomeController(IEmployeeRepository employeeRepository)
    {
        _employeeRepository = employeeRepository;
    }

    [HttpGet]
    public ViewResult Create()
    {
        return View();
    }

    [HttpPost]
    public IActionResult Create(Employee employee)
    {
        if (ModelState.IsValid)
        {
            Employee newEmployee = _employeeRepository.Add(employee);
        }

        return View();
    }
}

Create View

@model Employee
@inject IEmployeeRepository empRepository

<form asp-controller="home" asp-action="create" method="post">
    <div>
        <label asp-for="Name"></label>
        <div>
            <input asp-for="Name">
        </div>
    </div>

    <div>
        <button type="submit">Create</button>
    </div>

    <div>
        Total Employees Count = @empRepository.GetAllEmployees().Count().ToString()
    </div>
</form>

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();
    services.AddSingleton<IEmployeeRepository, MockEmployeeRepository>();
}

Copy-paste this code and press on the create button in the view and switch between AddSingleton , AddScoped and AddTransient you will get each time a different result that will might help you understand this.

AddSingleton() - As the name implies, AddSingleton() method creates a Singleton service. A Singleton service is created when it is first requested. This same instance is then used by all the subsequent requests. So in general, a Singleton service is created only one time per application and that single instance is used throughout the application life time.

AddTransient() - This method creates a Transient service. A new instance of a Transient service is created each time it is requested.

AddScoped() - This method creates a Scoped service. A new instance of a Scoped service is created once per request within the scope. For example, in a web application it creates 1 instance per each http request but uses the same instance in the other calls within that same web request.

Import a file from a subdirectory?

Create an empty file __init__.py in subdirectory /lib. And add at the begin of main code

from __future__ import absolute_import 

then

import lib.BoxTime as BT
...
BT.bt_function()

or better

from lib.BoxTime import bt_function
...
bt_function()

window.location.href not working

Please check you are using // not \\ by-mistake , like below

Wrong:"http:\\stackoverflow.com"

Right:"http://stackoverflow.com"

"X does not name a type" error in C++

When the compiler compiles the class User and gets to the MyMessageBox line, MyMessageBox has not yet been defined. The compiler has no idea MyMessageBox exists, so cannot understand the meaning of your class member.

You need to make sure MyMessageBox is defined before you use it as a member. This is solved by reversing the definition order. However, you have a cyclic dependency: if you move MyMessageBox above User, then in the definition of MyMessageBox the name User won't be defined!

What you can do is forward declare User; that is, declare it but don't define it. During compilation, a type that is declared but not defined is called an incomplete type. Consider the simpler example:

struct foo; // foo is *declared* to be a struct, but that struct is not yet defined

struct bar
{
    // this is okay, it's just a pointer;
    // we can point to something without knowing how that something is defined
    foo* fp; 

    // likewise, we can form a reference to it
    void some_func(foo& fr);

    // but this would be an error, as before, because it requires a definition
    /* foo fooMember; */
};

struct foo // okay, now define foo!
{
    int fooInt;
    double fooDouble;
};

void bar::some_func(foo& fr)
{
    // now that foo is defined, we can read that reference:
    fr.fooInt = 111605;
    fr.foDouble = 123.456;
}

By forward declaring User, MyMessageBox can still form a pointer or reference to it:

class User; // let the compiler know such a class will be defined

class MyMessageBox
{
public:
    // this is ok, no definitions needed yet for User (or Message)
    void sendMessage(Message *msg, User *recvr); 

    Message receiveMessage();
    vector<Message>* dataMessageList;
};

class User
{
public:
    // also ok, since it's now defined
    MyMessageBox dataMsgBox;
};

You cannot do this the other way around: as mentioned, a class member needs to have a definition. (The reason is that the compiler needs to know how much memory User takes up, and to know that it needs to know the size of its members.) If you were to say:

class MyMessageBox;

class User
{
public:
    // size not available! it's an incomplete type
    MyMessageBox dataMsgBox;
};

It wouldn't work, since it doesn't know the size yet.


On a side note, this function:

 void sendMessage(Message *msg, User *recvr);

Probably shouldn't take either of those by pointer. You can't send a message without a message, nor can you send a message without a user to send it to. And both of those situations are expressible by passing null as an argument to either parameter (null is a perfectly valid pointer value!)

Rather, use a reference (possibly const):

 void sendMessage(const Message& msg, User& recvr);

How to run the Python program forever?

Yes, you can use a while True: loop that never breaks to run Python code continually.

However, you will need to put the code you want to run continually inside the loop:

#!/usr/bin/python

while True:
    # some python code that I want 
    # to keep on running

Also, time.sleep is used to suspend the operation of a script for a period of time. So, since you want yours to run continually, I don't see why you would use it.

Can't get value of input type="file"?

You can read it, but you can't set it. value="123" will be ignored, so it won't have a value until you click on it and pick a file.

Even then, the value will likely be mangled with something like c:\fakepath\ to keep the details of the user's filesystem private.

Unable to find the requested .Net Framework Data Provider. It may not be installed. - when following mvc3 asp.net tutorial

In my case, the issue was caused by a connection problem to the SQL database. I just disconnected and then reconnected the SQL datasource from the design view. I am back up and running. Hope this works for everyone.

how to set cursor style to pointer for links without hrefs

Just add this to your global CSS style:

a { cursor: pointer; }

This way you're not dependent on the browser default cursor style anymore.

how to access master page control from content page

If you are trying to access an html element: this is an HTML Anchor...

My nav bar has items that are not list items (<li>) but rather html anchors (<a>)

See below: (This is the site master)

<nav class="mdl-navigation">
    <a class="mdl-navigation__link" href="" runat="server" id="liHome">Home</a>
    <a class="mdl-navigation__link" href="" runat="server" id="liDashboard">Dashboard</a>
</nav>

Now in your code behind for another page, for mine, it's the login page...

On PageLoad() define this:

HtmlAnchor lblMasterStatus = (HtmlAnchor)Master.FindControl("liHome");
lblMasterStatus.Visible =false;

HtmlAnchor lblMasterStatus1 = (HtmlAnchor)Master.FindControl("liDashboard");
lblMasterStatus1.Visible = false;

Now we have accessed the site masters controls, and have made them invisible on the login page.

Add objects to an array of objects in Powershell

To append to an array, just use the += operator.

$Target += $TargetObject

Also, you need to declare $Target = @() before your loop because otherwise, it will empty the array every loop.

fcntl substitute on Windows

Although this does not help you right away, there is an alternative that can work with both Unix (fcntl) and Windows (win32 api calls), called: portalocker

It describes itself as a cross-platform (posix/nt) API for flock-style file locking for Python. It basically maps fcntl to win32 api calls.

The original code at http://code.activestate.com/recipes/65203/ can now be installed as a separate package - https://pypi.python.org/pypi/portalocker

Span inside anchor or anchor inside span or doesn't matter?

that depends on what you want to markup.

  • if you want a link inside a span, put <a> inside <span>.
  • if you want to markup something in a link, put <span> into <a>

Laravel view not found exception

If your path to view is true first try to config:cache and route:cache if nothing changed check your resource path permission are true.

example: your can do it in ubuntu with :

sudo chgrp -R www-data resources/views
sudo usermod -a -G www-data $USER

Efficient way to determine number of digits in an integer

template <typename type>
class number_of_decimal_digits {   
    const powers_and_max<type> mPowersAndMax;
public:
    number_of_decimal_digits(){
    }   
    inline size_t ndigits( type i) const {
        if(i<0){
             i += (i == std::numeric_limits<type>::min());
             i=-i;
        }
        const type* begin = &*mPowersAndMax.begin();
        const type* end = begin+mPowersAndMax.size();
        return 1 + std::lower_bound(begin,end,i) - begin;
    }
    inline size_t string_ndigits(const type& i) const {
        return (i<0) + ndigits(i);
    }
    inline size_t operator[](const type& i) const {
       return string_ndigits(i);
    }
};

where in powers_and_max we have (10^n)-1 for all n such that

(10^n) < std::numeric_limits<type>::max()

and std::numeric_limits<type>::max() in an array:

template <typename type>
struct powers_and_max : protected std::vector<type>{
    typedef std::vector<type> super;
    using super::const_iterator;
    using super::size;
    type& operator[](size_t i)const{return super::operator[](i)};
    const_iterator begin()const {return super::begin();} 
    const_iterator end()const {return super::end();} 
    powers_and_max() {
       const int size = (int)(log10(double(std::numeric_limits<type>::max())));
       int j = 0;
       type i = 10;
       for( ; j<size ;++j){
           push_back(i-1);//9,99,999,9999 etc;
           i*=10;
       }
       ASSERT(back()<std::numeric_limits<type>::max());
       push_back(std::numeric_limits<type>::max());
   }
};

here's a simple test:

number_of_decimal_digits<int>  ndd;
ASSERT(ndd[0]==1);
ASSERT(ndd[9]==1);
ASSERT(ndd[10]==2);
ASSERT(ndd[-10]==3);
ASSERT(ndd[-1]==2);
ASSERT(ndd[-9]==2);
ASSERT(ndd[1000000000]==10);
ASSERT(ndd[0x7fffffff]==10);
ASSERT(ndd[-1000000000]==11);
ASSERT(ndd[0x80000000]==11);

Of course any other implementation of an ordered set might be used for powers_and_max and if there was knowledge that there would be clustering but no knowledge of where the cluster might be perhaps a self adjusting tree implementation might be best

Still Reachable Leak detected by Valgrind

You don't appear to understand what still reachable means.

Anything still reachable is not a leak. You don't need to do anything about it.

Another Repeated column in mapping for entity error

Hope this will help!

@OneToOne(optional = false)
    @JoinColumn(name = "department_id", insertable = false, updatable = false)
    @JsonManagedReference
    private Department department;

@JsonIgnore
    public Department getDepartment() {
        return department;
    }

@OneToOne(mappedBy = "department")
private Designation designation;

@JsonIgnore
    public Designation getDesignation() {
        return designation;
    }

Search a whole table in mySQL for a string

Try this code,

SELECT 
       * 
FROM 
       `customers` 
WHERE 
       (
          CONVERT 
               (`customer_code` USING utf8mb4) LIKE '%Mary%' 
          OR 
          CONVERT(`customer_name` USING utf8mb4) LIKE '%Mary%' 
          OR 
          CONVERT(`email_id` USING utf8mb4) LIKE '%Mary%' 
          OR 
          CONVERT(`address1` USING utf8mb4) LIKE '%Mary%' 
          OR
          CONVERT(`report_sorting` USING utf8mb4) LIKE '%Mary%'
       )

This is help to solve your problem mysql version 5.7.21

How can I get a collection of keys in a JavaScript dictionary?

This will work in all JavaScript implementations:

var keys = [];

for (var key in driversCounter) {
    if (driversCounter.hasOwnProperty(key)) {
        keys.push(key);
    }
}

Like others mentioned before you may use Object.keys, but it may not work in older engines. So you can use the following monkey patch:

if (!Object.keys) {
    Object.keys = function (object) {
        var keys = [];

        for (var key in object) {
            if (object.hasOwnProperty(key)) {
                keys.push(key);
            }
        }
    }
}

-XX:MaxPermSize with or without -XX:PermSize

By playing with parameters as -XX:PermSize and -Xms you can tune the performance of - for example - the startup of your application. I haven't looked at it recently, but a few years back the default value of -Xms was something like 32MB (I think), if your application required a lot more than that it would trigger a number of cycles of fill memory - full garbage collect - increase memory etc until it had loaded everything it needed. This cycle can be detrimental for startup performance, so immediately assigning the number required could improve startup.

A similar cycle is applied to the permanent generation. So tuning these parameters can improve startup (amongst others).

WARNING The JVM has a lot of optimization and intelligence when it comes to allocating memory, dividing eden space and older generations etc, so don't do things like making -Xms equal to -Xmx or -XX:PermSize equal to -XX:MaxPermSize as it will remove some of the optimizations the JVM can apply to its allocation strategies and therefor reduce your application performance instead of improving it.

As always: make non-trivial measurements to prove your changes actually improve performance overall (for example improving startup time could be disastrous for performance during use of the application)

git diff file against its last change

If you are fine using a graphical tool this works very well:

gitk <file>

gitk now shows all commits where the file has been updated. Marking a commit will show you the diff against the previous commit in the list. This also works for directories, but then you also get to select the file to diff for the selected commit. Super useful!

MongoError: connect ECONNREFUSED 127.0.0.1:27017

For Windows users.

This happens because the MondgDB server is stopped. to fix this you can,

  1. 1 search for Services ,for that search using the left bottom corner search option.

    2 then there is a gear icon named with 'Services'.

    3 after clicking that you will get a window with lot of services

    4 scroll down and you will find 'MongoDB server (MongoDB)'.

    5 so you will see that there is an option to start the service.

    6 start it.

  2. 1 then open your command prompt.

    2 type mongod

now you can connect to your server.

this steps also working fine if your sql server service down. (find sql server services)

Reset CSS display property to default value

No, it is generally not possible. Once some CSS (or HTML) code sets a value for a property on an element, there is no way to undo it and tell the browser to use its default value.

It is of course possible to set a property a value that you expect to be the default value. This may work rather widely if you check the Rendering section of HTML5 CR, mostly reflecting what browsers actually do.

Still, the answer is “No”, because browsers may have whatever default values they like. You should analyze what was the reason for wanting to reset to defaults; the original problem may still be solvable.

Java synchronized method lock on object, or method?

This example (although not pretty one) can provide more insight into locking mechanism. If incrementA is synchronized, and incrementB is not synchronized, then incrementB will be executed ASAP, but if incrementB is also synchronized then it has to 'wait' for incrementA to finish, before incrementB can do its job.

Both methods are called onto single instance - object, in this example it is: job, and 'competing' threads are aThread and main.

Try with 'synchronized' in incrementB and without it and you will see different results.If incrementB is 'synchronized' as well then it has to wait for incrementA() to finish. Run several times each variant.

class LockTest implements Runnable {
    int a = 0;
    int b = 0;

    public synchronized void incrementA() {
        for (int i = 0; i < 100; i++) {
            this.a++;
            System.out.println("Thread: " + Thread.currentThread().getName() + "; a: " + this.a);
        }
    }

    // Try with 'synchronized' and without it and you will see different results
    // if incrementB is 'synchronized' as well then it has to wait for incrementA() to finish

    // public void incrementB() {
    public synchronized void incrementB() {
        this.b++;
        System.out.println("*************** incrementB ********************");
        System.out.println("Thread: " + Thread.currentThread().getName() + "; b: " + this.b);
        System.out.println("*************** incrementB ********************");
    }

    @Override
    public void run() {
        incrementA();
        System.out.println("************ incrementA completed *************");
    }
}

class LockTestMain {
    public static void main(String[] args) throws InterruptedException {
        LockTest job = new LockTest();
        Thread aThread = new Thread(job);
        aThread.setName("aThread");
        aThread.start();
        Thread.sleep(1);
        System.out.println("*************** 'main' calling metod: incrementB **********************");
        job.incrementB();
    }
}

R: invalid multibyte string

I figured out Leafpad to be an adequate and simple text-editor to view and save/convert in certain character sets - at least in the linux-world.

I used this to save the Latin-15 to UTF-8 and it worked.

How to call a function in shell Scripting?

You don't specify which shell (there are many), so I am assuming Bourne Shell, that is I think your script starts with:

#!/bin/sh

Please remember to tag future questions with the shell type, as this will help the community answer your question.

You need to define your functions before you call them. Using ():

process_install()
{
    echo "Performing process_install() commands, using arguments [${*}]..."
}

process_exit()
{
    echo "Performing process_exit() commands, using arguments [${*}]..."
}

Then you can call your functions, just as if you were calling any command:

if [ "$choice" = "true" ]
then
    process_install foo bar
elif [ "$choice" = "false" ]
then
    process_exit baz qux

You may also wish to check for invalid choices at this juncture...

else
    echo "Invalid choice [${choice}]..."
fi

See it run with three different values of ${choice}.

Good luck!

How to get my Android device Internal Download Folder path

if a device has an SD card, you use:

Environment.getExternalStorageState() 

if you don't have an SD card, you use:

Environment.getDataDirectory()

if there is no SD card, you can create your own directory on the device locally.

    //if there is no SD card, create new directory objects to make directory on device
        if (Environment.getExternalStorageState() == null) {
                        //create new file directory object
            directory = new File(Environment.getDataDirectory()
                    + "/RobotiumTestLog/");
            photoDirectory = new File(Environment.getDataDirectory()
                    + "/Robotium-Screenshots/");
            /*
             * this checks to see if there are any previous test photo files
             * if there are any photos, they are deleted for the sake of
             * memory
             */
            if (photoDirectory.exists()) {
                File[] dirFiles = photoDirectory.listFiles();
                if (dirFiles.length != 0) {
                    for (int ii = 0; ii <= dirFiles.length; ii++) {
                        dirFiles[ii].delete();
                    }
                }
            }
            // if no directory exists, create new directory
            if (!directory.exists()) {
                directory.mkdir();
            }

            // if phone DOES have sd card
        } else if (Environment.getExternalStorageState() != null) {
            // search for directory on SD card
            directory = new File(Environment.getExternalStorageDirectory()
                    + "/RobotiumTestLog/");
            photoDirectory = new File(
                    Environment.getExternalStorageDirectory()
                            + "/Robotium-Screenshots/");
            if (photoDirectory.exists()) {
                File[] dirFiles = photoDirectory.listFiles();
                if (dirFiles.length > 0) {
                    for (int ii = 0; ii < dirFiles.length; ii++) {
                        dirFiles[ii].delete();
                    }
                    dirFiles = null;
                }
            }
            // if no directory exists, create new directory to store test
            // results
            if (!directory.exists()) {
                directory.mkdir();
            }
        }// end of SD card checking

add permissions on your manifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Happy coding..

sass :first-child not working

First of all, there are still browsers out there that don't support those pseudo-elements (ie. :first-child, :last-child), so you have to 'deal' with this issue.

There is a good example how to make that work without using pseudo-elements:

http://www.darowski.com/tracesofinspiration/2010/01/11/this-newbies-first-impressions-of-haml-and-sass/

       -- see the divider pipe example.

I hope that was useful.

Is it possible to deserialize XML into List<T>?

Yes, it does deserialize to List<>. No need to keep it in an array and wrap/encapsulate it in a list.

public class UserHolder
{
    private List<User> users = null;

    public UserHolder()
    {
    }

    [XmlElement("user")]
    public List<User> Users
    {
        get { return users; }
        set { users = value; }
    }
}

Deserializing code,

XmlSerializer xs = new XmlSerializer(typeof(UserHolder));
UserHolder uh = (UserHolder)xs.Deserialize(new StringReader(str));

Submitting a form by pressing enter without a submit button

I work with a bunch of UI frameworks. Many of them have a built-in class you can use to visually hide things.

Bootstrap

<input type="submit" class="sr-only" tabindex="-1">

Angular Material

<input type="submit" class="cdk-visually-hidden" tabindex="-1">

Brilliant minds who created these frameworks have defined these styles as follows:

.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

.cdk-visually-hidden {
    border: 0;
    clip: rect(0 0 0 0);
    height: 1px;
    margin: -1px;
    overflow: hidden;
    padding: 0;
    position: absolute;
    width: 1px;
    outline: 0;
    -webkit-appearance: none;
    -moz-appearance: none;
}

How to use mongoimport to import csv

Just use this after executing mongoimport

It will return number of objects imported

use db
db.collectionname.find().count()

will return the number of objects.

Referencing value in a closed Excel workbook using INDIRECT?

This seems to work with closed file: add a pivot table (rows, tabular layout, no subtotals, no grand totals) of the source to the current workbook, then reference all you want from that pivot table, INDIRECT, LOOKUPs,...

Apache POI error loading XSSFWorkbook class

Hurrah! Adding commons-collections jar files to my project resolved this problem. Two thumbs up to Lucky Sharma.

Solution: Add commons-collections4-4.1.jar file in your build path and try it again. It will work.

You can download it from https://mvnrepository.com/artifact/org.apache.commons/commons-collections4/4.1

Doing a join across two databases with different collations on SQL Server and getting an error

You can use the collate clause in a query (I can't find my example right now, so my syntax is probably wrong - I hope it points you in the right direction)

select sone_field collate SQL_Latin1_General_CP850_CI_AI
  from table_1
    inner join table_2
      on (table_1.field collate SQL_Latin1_General_CP850_CI_AI = table_2.field)
  where whatever

How to sort multidimensional array by column?

sorted(list, key=lambda x: x[1])

Note: this works on time variable too.

Fastest way to convert string to integer in PHP

Run a test.

   string coerce:          7.42296099663
   string cast:            8.05654597282
   string fail coerce:     7.14159703255
   string fail cast:       7.87444186211

This was a test that ran each scenario 10,000,000 times. :-)

Co-ercion is 0 + "123"

Casting is (integer)"123"

I think Co-ercion is a tiny bit faster. Oh, and trying 0 + array('123') is a fatal error in PHP. You might want your code to check the type of the supplied value.

My test code is below.


function test_string_coerce($s) {
    return 0 + $s;
}

function test_string_cast($s) {
    return (integer)$s;
}

$iter = 10000000;

print "-- running each text $iter times.\n";

// string co-erce
$string_coerce = new Timer;
$string_coerce->Start();

print "String Coerce test\n";
for( $i = 0; $i < $iter ; $i++ ) {
    test_string_coerce('123');
}

$string_coerce->Stop();

// string cast
$string_cast = new Timer;
$string_cast->Start();

print "String Cast test\n";
for( $i = 0; $i < $iter ; $i++ ) {
    test_string_cast('123');
}

$string_cast->Stop();

// string co-erce fail.
$string_coerce_fail = new Timer;
$string_coerce_fail->Start();

print "String Coerce fail test\n";
for( $i = 0; $i < $iter ; $i++ ) {
    test_string_coerce('hello');
}

$string_coerce_fail->Stop();

// string cast fail
$string_cast_fail = new Timer;
$string_cast_fail->Start();

print "String Cast fail test\n";
for( $i = 0; $i < $iter ; $i++ ) {
    test_string_cast('hello');
}

$string_cast_fail->Stop();

// -----------------
print "\n";
print "string coerce:          ".$string_coerce->Elapsed()."\n";
print "string cast:            ".$string_cast->Elapsed()."\n";
print "string fail coerce:     ".$string_coerce_fail->Elapsed()."\n";
print "string fail cast:       ".$string_cast_fail->Elapsed()."\n";


class Timer {
    var $ticking = null;
    var $started_at = false;
    var $elapsed = 0;

    function Timer() {
        $this->ticking = null;
    }

    function Start() {
        $this->ticking = true;
        $this->started_at = microtime(TRUE);
    }

    function Stop() {
        if( $this->ticking )
            $this->elapsed = microtime(TRUE) - $this->started_at;
        $this->ticking = false;
    }

    function Elapsed() {
        switch( $this->ticking ) {
            case true: return "Still Running";
            case false: return $this->elapsed;
            case null: return "Not Started";
        }
    }
}

How to delete large data of table in SQL without log?

@m-ali answer is right but also keep in mind that logs could grow a lot if you don't commit the transaction after each chunk and perform a checkpoint. This is how I would do it and take this article http://sqlperformance.com/2013/03/io-subsystem/chunk-deletes as reference, with performance tests and graphs:

DECLARE @Deleted_Rows INT;
SET @Deleted_Rows = 1;


WHILE (@Deleted_Rows > 0)
  BEGIN

   BEGIN TRANSACTION

   -- Delete some small number of rows at a time
     DELETE TOP (10000)  LargeTable 
     WHERE readTime < dateadd(MONTH,-7,GETDATE())

     SET @Deleted_Rows = @@ROWCOUNT;

   COMMIT TRANSACTION
   CHECKPOINT -- for simple recovery model
END

Getting only hour/minute of datetime

I would recommend keeping the object you have, and just utilizing the properties that you want, rather than removing the resolution you already have.

If you want to print it in a certain format you may want to look at this...That way you can preserve your resolution further down the line.

That being said you can create a new DateTime object using only the properties you want as @romkyns has in his answer.

Regex date validation for yyyy-mm-dd

You can use this regex to get the yyyy-MM-dd format:

((?:19|20)\\d\\d)-(0?[1-9]|1[012])-([12][0-9]|3[01]|0?[1-9])

You can find example for date validation: How to validate date with regular expression.

How do I view the full content of a text or varchar(MAX) column in SQL Server 2008 Management Studio?

The data type TEXT is old and should not be used anymore, it is a pain to select data out of a TEXT column.

ntext, text, and image (Transact-SQL)

ntext, text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

you need to use TEXTPTR (Transact-SQL) to retrieve the text data.

Also see this article on Handling The Text Data Type.

Releasing memory in Python

eryksun has answered question #1, and I've answered question #3 (the original #4), but now let's answer question #2:

Why does it release 50.5mb in particular - what is the amount that is released based on?

What it's based on is, ultimately, a whole series of coincidences inside Python and malloc that are very hard to predict.

First, depending on how you're measuring memory, you may only be measuring pages actually mapped into memory. In that case, any time a page gets swapped out by the pager, memory will show up as "freed", even though it hasn't been freed.

Or you may be measuring in-use pages, which may or may not count allocated-but-never-touched pages (on systems that optimistically over-allocate, like linux), pages that are allocated but tagged MADV_FREE, etc.

If you really are measuring allocated pages (which is actually not a very useful thing to do, but it seems to be what you're asking about), and pages have really been deallocated, two circumstances in which this can happen: Either you've used brk or equivalent to shrink the data segment (very rare nowadays), or you've used munmap or similar to release a mapped segment. (There's also theoretically a minor variant to the latter, in that there are ways to release part of a mapped segment—e.g., steal it with MAP_FIXED for a MADV_FREE segment that you immediately unmap.)

But most programs don't directly allocate things out of memory pages; they use a malloc-style allocator. When you call free, the allocator can only release pages to the OS if you just happen to be freeing the last live object in a mapping (or in the last N pages of the data segment). There's no way your application can reasonably predict this, or even detect that it happened in advance.

CPython makes this even more complicated—it has a custom 2-level object allocator on top of a custom memory allocator on top of malloc. (See the source comments for a more detailed explanation.) And on top of that, even at the C API level, much less Python, you don't even directly control when the top-level objects are deallocated.

So, when you release an object, how do you know whether it's going to release memory to the OS? Well, first you have to know that you've released the last reference (including any internal references you didn't know about), allowing the GC to deallocate it. (Unlike other implementations, at least CPython will deallocate an object as soon as it's allowed to.) This usually deallocates at least two things at the next level down (e.g., for a string, you're releasing the PyString object, and the string buffer).

If you do deallocate an object, to know whether this causes the next level down to deallocate a block of object storage, you have to know the internal state of the object allocator, as well as how it's implemented. (It obviously can't happen unless you're deallocating the last thing in the block, and even then, it may not happen.)

If you do deallocate a block of object storage, to know whether this causes a free call, you have to know the internal state of the PyMem allocator, as well as how it's implemented. (Again, you have to be deallocating the last in-use block within a malloced region, and even then, it may not happen.)

If you do free a malloced region, to know whether this causes an munmap or equivalent (or brk), you have to know the internal state of the malloc, as well as how it's implemented. And this one, unlike the others, is highly platform-specific. (And again, you generally have to be deallocating the last in-use malloc within an mmap segment, and even then, it may not happen.)

So, if you want to understand why it happened to release exactly 50.5mb, you're going to have to trace it from the bottom up. Why did malloc unmap 50.5mb worth of pages when you did those one or more free calls (for probably a bit more than 50.5mb)? You'd have to read your platform's malloc, and then walk the various tables and lists to see its current state. (On some platforms, it may even make use of system-level information, which is pretty much impossible to capture without making a snapshot of the system to inspect offline, but luckily this isn't usually a problem.) And then you have to do the same thing at the 3 levels above that.

So, the only useful answer to the question is "Because."

Unless you're doing resource-limited (e.g., embedded) development, you have no reason to care about these details.

And if you are doing resource-limited development, knowing these details is useless; you pretty much have to do an end-run around all those levels and specifically mmap the memory you need at the application level (possibly with one simple, well-understood, application-specific zone allocator in between).

How to change Screen buffer size in Windows Command Prompt from batch script

There's a solution at CMD: Set buffer height independently of window height effectively employing a powershell command executed from the batch script. This solution let me resize the scrollback buffer in the existing batch script window independently of the window size, exactly what the OP was asking for.

Caveat: It seems to make the script forget variables (or at least it did with my script), so I recommend calling the command only at the beginning and / or end of your script, or otherwise where you don't depend on a session local variable.

"Sources directory is already netbeans project" error when opening a project from existing sources

In my case my project root directory consists ".project". This contain the XML reference of the project name.

By removing this, i am able to create a project.

Detect IE version (prior to v9) in JavaScript

Detecting IE version using feature detection (IE6+, browsers prior to IE6 are detected as 6, returns null for non-IE browsers):

var ie = (function (){
    if (window.ActiveXObject === undefined) return null; //Not IE
    if (!window.XMLHttpRequest) return 6;
    if (!document.querySelector) return 7;
    if (!document.addEventListener) return 8;
    if (!window.atob) return 9;
    if (!document.__proto__) return 10;
    return 11;
})();

Edit: I've created a bower/npm repo for your convenience: ie-version

Update:

a more compact version can be written in one line as:

return window.ActiveXObject === undefined ? null : !window.XMLHttpRequest ? 6 : !document.querySelector ? 7 : !document.addEventListener ? 8 : !window.atob ? 9 : !document.__proto__ ? 10 : 11;

convert array into DataFrame in Python

In general you can use pandas rename function here. Given your dataframe you could change to a new name like this. If you had more columns you could also rename those in the dictionary. The 0 is the current name of your column

import pandas as pd    
import numpy as np   
e = np.random.normal(size=100)  
e_dataframe = pd.DataFrame(e)      

e_dataframe.rename(index=str, columns={0:'new_column_name'})

Editing hosts file to redirect url?

hosts file:

1.2.3.4 google.com

1.2.3.4 - ip of your server.

Run script on the server for redirecting users to url that you want.

How to append data to div using JavaScript?

you can use jQuery. which make it very simple.

just download the jQuery file add jQuery into your HTML
or you can user online link:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>

and try this:

 $("#divID").append(data);

Print a file, skipping the first X lines, in Bash

Just to propose a sed alternative. :) To skip first one million lines, try |sed '1,1000000d'.

Example:

$ perl -wle 'print for (1..1_000_005)'|sed '1,1000000d'
1000001
1000002
1000003
1000004
1000005

HTML Table width in percentage, table rows separated equally

you can try this, I would do it with CSS, but i think you want it with tables without CSS.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
   <body leftmargin=0 rightmargin=0>
      <table cellpadding="0" cellspacing="0" width="100%" border="1" height="350px"> 
         <tr>
            <td width="25%">&nbsp;</td>
            <td width="25%">&nbsp;</td>
            <td width="25%">&nbsp;</td>
            <td width="25%">&nbsp;</td>
         </tr>
      </table> 
   </body>
</html>

jQuery - checkbox enable/disable

_x000D_
_x000D_
$(document).ready(function() {_x000D_
  $('#InventoryMasterError').click(function(event) { //on click_x000D_
    if (this.checked) { // check select status_x000D_
      $('.checkerror').each(function() { //loop through each checkbox_x000D_
        $('#selecctall').attr('disabled', 'disabled');_x000D_
      });_x000D_
    } else {_x000D_
      $('.checkerror').each(function() { //loop through each checkbox_x000D_
        $('#selecctall').removeAttr('disabled', 'disabled');_x000D_
      });_x000D_
    }_x000D_
  });_x000D_
_x000D_
});_x000D_
_x000D_
$(document).ready(function() {_x000D_
  $('#selecctall').click(function(event) { //on click_x000D_
    if (this.checked) { // check select status_x000D_
      $('.checkbox1').each(function() { //loop through each checkbox_x000D_
        $('#InventoryMasterError').attr('disabled', 'disabled');_x000D_
      });_x000D_
_x000D_
    } else {_x000D_
      $('.checkbox1').each(function() { //loop through each checkbox_x000D_
        $('#InventoryMasterError').removeAttr('disabled', 'disabled');_x000D_
      });_x000D_
    }_x000D_
  });_x000D_
});
_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
<input type="checkbox" id="selecctall" name="selecctall" value="All" />_x000D_
<input type="checkbox" name="data[InventoryMaster][error]" label="" value="error" id="InventoryMasterError" />_x000D_
<input type="checkbox" name="checkid[]" class="checkbox1" value="1" id="InventoryMasterId" />_x000D_
<input type="checkbox" name="checkid[]" class="checkbox1" value="2" id="InventoryMasterId" />
_x000D_
_x000D_
_x000D_

Get current clipboard content?

Following will give you the selected content as well as updating the clipboard.

Bind the element id with copy event and then get the selected text. You could replace or modify the text. Get the clipboard and set the new text. To get the exact formatting you need to set the type as "text/hmtl". You may also bind it to the document instead of element.

document.querySelector('element').bind('copy', function(event) {
  var selectedText = window.getSelection().toString(); 
  selectedText = selectedText.replace(/\u200B/g, "");

  clipboardData = event.clipboardData || window.clipboardData || event.originalEvent.clipboardData;
  clipboardData.setData('text/html', selectedText);

  event.preventDefault();
});

Need to find a max of three numbers in java

You should know more about java.lang.Math.max:

  1. java.lang.Math.max(arg1,arg2) only accepts 2 arguments but you are writing 3 arguments in your code.
  2. The 2 arguments should be double,int,long and float but your are writing String arguments in Math.max function. You need to parse them in the required type.

You code will produce compile time error because of above mismatches.

Try following updated code, that will solve your purpose:

import java.lang.Math;
import java.util.Scanner;
public class max {
    public static void main(String[] args) {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Please input 3 integers: ");
        int x = Integer.parseInt(keyboard.nextLine());
        int y = Integer.parseInt(keyboard.nextLine());
        int z = Integer.parseInt(keyboard.nextLine());
        int max = Math.max(x,y);
        if(max>y){ //suppose x is max then compare x with z to find max number
            max = Math.max(x,z);    
        }
        else{ //if y is max then compare y with z to find max number
            max = Math.max(y,z);    
        }
        System.out.println("The max of three is: " + max);
    }
} 

generating variable names on fly in python

Another example, which is really a variation of another answer, in that it uses a dictionary too:

>>> vr={} 
... for num in range(1,4): 
...     vr[str(num)] = 5 + num
...     
>>> print vr["3"]
8
>>> 

Convert Swift string to array

It is even easier in Swift:

let string : String = "Hello  "
let characters = Array(string)
println(characters)
// [H, e, l, l, o,  , , ,  , ]

This uses the facts that

  • an Array can be created from a SequenceType, and
  • String conforms to the SequenceType protocol, and its sequence generator enumerates the characters.

And since Swift strings have full support for Unicode, this works even with characters outside of the "Basic Multilingual Plane" (such as ) and with extended grapheme clusters (such as , which is actually composed of two Unicode scalars).


Update: As of Swift 2, String does no longer conform to SequenceType, but the characters property provides a sequence of the Unicode characters:

let string = "Hello  "
let characters = Array(string.characters)
print(characters)

This works in Swift 3 as well.


Update: As of Swift 4, String is (again) a collection of its Characters:

let string = "Hello  "
let characters = Array(string)
print(characters)
// ["H", "e", "l", "l", "o", " ", "", "", " ", ""]

How to use a variable in the replacement side of the Perl substitution operator?

# perl -de 0
$match="hi(.*)"
$sub='$1'
$res="hi1234"
$res =~ s/$match/$sub/gee
p $res
  1234

Be careful, though. This causes two layers of eval to occur, one for each e at the end of the regex:

  1. $sub --> $1
  2. $1 --> final value, in the example, 1234

How do I explicitly specify a Model's table-name mapping in Rails?

class Countries < ActiveRecord::Base
    self.table_name = "cc"
end

In Rails 3.x this is the way to specify the table name.

Using Google maps API v3 how do I get LatLng with a given address?

I don't think location.LatLng is working, however this works:

results[0].geometry.location.lat(), results[0].geometry.location.lng()

Found it while exploring Get Lat Lon source code.

CSS border less than 1px

A pixel is the smallest unit value to render something with, but you can trick thickness with optical illusions by modifying colors (the eye can only see up to a certain resolution too).

Here is a test to prove this point:

_x000D_
_x000D_
div { border-color: blue; border-style: solid; margin: 2px; }

div.b1 { border-width: 1px; }
div.b2 { border-width: 0.1em; }
div.b3 { border-width: 0.01em; }
div.b4 { border-width: 1px; border-color: rgb(160,160,255); }
_x000D_
<div class="b1">Some text</div>
<div class="b2">Some text</div>
<div class="b3">Some text</div>
<div class="b4">Some text</div>
_x000D_
_x000D_
_x000D_

Output

enter image description here

Which gives the illusion that the last DIV has a smaller border width, because the blue border blends more with the white background.


Edit: Alternate solution

Alpha values may also be used to simulate the same effect, without the need to calculate and manipulate RGB values.

_x000D_
_x000D_
.container {
  border-style: solid;
  border-width: 1px;
  
  margin-bottom: 10px;
}

.border-100 { border-color: rgba(0,0,255,1); }
.border-75 { border-color: rgba(0,0,255,0.75); }
.border-50 { border-color: rgba(0,0,255,0.5); }
.border-25 { border-color: rgba(0,0,255,0.25); }
_x000D_
<div class="container border-100">Container 1 (alpha = 1)</div>
<div class="container border-75">Container 2 (alpha = 0.75)</div>
<div class="container border-50">Container 3 (alpha = 0.5)</div>
<div class="container border-25">Container 4 (alpha = 0.25)</div>
_x000D_
_x000D_
_x000D_

How to count the number of rows in excel with data?

These would both work as well, letting Excel define the last time it sees data

numofrows = destsheet.UsedRange.SpecialCells(xlLastCell).row

numofrows = destsheet.Cells.SpecialCells(xlLastCell).row

Uncaught TypeError: $(...).datepicker is not a function(anonymous function)

This error is occur,because the function is not defined. In my case i have called the datepicker function without including the datepicker js file that time I got this error.

HTML img tag: title attribute vs. alt attribute?

You should not use title attribute for the img element. The reasoning behind this is quite simple:

Presumably caption information is important information that should be available to all users by default. If so present this content as text next to the image.

Source: http://blog.paciellogroup.com/2010/11/using-the-html-title-attribute/

HTML 5.1 includes general advice on use of the title attribute:

Relying on the title attribute is currently discouraged as many user agents do not expose the attribute in an accessible manner as required by this specification (e.g. requiring a pointing device such as a mouse to cause a tooltip to apear, which excludes keyboard-only users and touch-only users, such as anyone with a modern phone or tablet).

Source: http://www.w3.org/html/wg/drafts/html/master/dom.html#the-title-attribute

When it comes to accessibility and different screen readers:

  • Jaws 10-11: turned off by default
  • Window-Eyes 7.02: turned on by default
  • NVDA: not supported (no support options)
  • VoiceOver: not supported (no support options)

Hence, as Denis Boudreau adequately put it: clearly not a recommended practice.

How can I display a messagebox in ASP.NET?

Alert message with redirect

Response.Write("<script language='javascript'>window.alert('Popup message ');window.location='webform.aspx';</script>");

Only alert message

Response.Write("<script language='javascript'>window.alert('Popup message ')</script>");

Nginx: Permission denied for nginx on Ubuntu

Permission to view log files is granted to users being in the group adm.

To add a user to this group on the command line issue:

sudo usermod -aG adm <USER>

What is aria-label and how should I use it?

In the example you give, you're perfectly right, you have to set the title attribute.

If the aria-label is one tool used by assistive technologies (like screen readers), it is not natively supported on browsers and has no effect on them. It won't be of any help to most of the people targetted by the WCAG (except screen reader users), for instance a person with intellectal disabilities.

The "X" is not sufficient enough to give information to the action led by the button (think about someone with no computer knowledge). It might mean "close", "delete", "cancel", "reduce", a strange cross, a doodle, nothing.

Despite the fact that the W3C seems to promote the aria-label rather that the title attribute here: http://www.w3.org/TR/2014/NOTE-WCAG20-TECHS-20140916/ARIA14 in a similar example, you can see that the technology support does not include standard browsers : http://www.w3.org/WAI/WCAG20/Techniques/ua-notes/aria#ARIA14

In fact aria-label, in this exact situation might be used to give more context to an action:

For instance, blind people do not perceive popups like those of us with good vision, it's like a change of context. "Back to the page" will be a more convenient alternative for a screen reader, when "Close" is more significant for someone with no screen reader.

  <button
      aria-label="Back to the page"
      title="Close" onclick="myDialog.close()">X</button>

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

There might be a fix to <input type="button"> - but if there is, I don't know it.

Otherwise, a good option seems to be to replace it with a carefully styled a element.

Example: http://jsfiddle.net/Uka5v/

.button {
    background-color: #E3E1B8; 
    padding: 2px 4px;
    font: 13px sans-serif;
    text-decoration: none;
    border: 1px solid #000;
    border-color: #aaa #444 #444 #aaa;
    color: #000
}

Upsides include that the a element will style consistently between different (older) versions of Internet Explorer without any extra work, and I think my link looks nicer than that button :)

How to use the 'og' (Open Graph) meta tag for Facebook share

I built a tool for meta generation. It pre-configures entries for Facebook, Google+ and Twitter, and you can use it free here: http://www.groovymeta.com

To answer the question a bit more, OG tags (Open Graph) tags work similarly to meta tags, and should be placed in the HEAD section of your HTML file. See Facebook's best practises for more information on how to use OG tags effectively.

How to convert Excel values into buckets?

I use this trick for equal data bucketing. Instead of text result you get the number. Here is example for four buckets. Suppose you have data in A1:A100 range. Put this formula in B1:

=MAX(ROUNDUP(PERCENTRANK($A$1:$A$100,A1) *4,0),1)

Fill down the formula all across B column and you are done. The formula divides the range into 4 equal buckets and it returns the bucket number which the cell A1 falls into. The first bucket contains the lowest 25% of values.

Adjust the number of buckets according to thy wish:

=MAX(ROUNDUP(PERCENTRANK([Range],[OneCellOfTheRangeToTest]) *[NumberOfBuckets],0),1)

The number of observation in each bucket will be equal or almost equal. For example if you have a 100 observations and you want to split it into 3 buckets (like in your example) then the buckets will contain 33, 33, 34 observations. So almost equal. You do not have to worry about that - the formula works that out for you.

MS SQL compare dates?

Use the DATEDIFF function with a datepart of day.

SELECT ...
FROM ...
WHERE DATEDIFF(day, date1, date2) >= 0

Note that if you want to test that date1 <= date2 then you need to test that DATEDIFF(day, date1, date2) >= 0, or alternatively you could test DATEDIFF(day, date2, date1) <= 0.

Visual Studio "Could not copy" .... during build

@Geoff's (https://stackoverflow.com/a/25251766/3739540) answer is good, but it throws error code 1 on recompile.

Here is what worked for me (2>nul 1>nul on the end + exit 0):

(if exist "$(TargetDir)*old.pdb" del "$(TargetDir)*old.pdb") & (if exist "$(TargetDir)*.pdb" ren "$(TargetDir)*.pdb" *.old.pdb) 2>nul 1>nul
(if exist "$(TargetDir)*old.dll" del "$(TargetDir)*old.dll") & (if exist "$(TargetDir)*.dll" ren "$(TargetDir)*.dll" *.old.dll) 2>nul 1>nul
exit 0

Can I bind an array to an IN() condition?

Looking at PDO :Predefined Constants there is no PDO::PARAM_ARRAY which you would need as is listed on PDOStatement->bindParam

bool PDOStatement::bindParam ( mixed $parameter , mixed &$variable [, int $data_type [, int $length [, mixed $driver_options ]]] )

So I don't think it is achievable.

How to run function of parent window when child window closes?

You probably want to use the 'onbeforeunload' event. It will allow you call a function in the parent window from the child immediately before the child window closes.

So probably something like this:

window.onbeforeunload = function (e) {
    window.parent.functonToCallBeforeThisWindowCloses();
};

How do I find out what is hammering my SQL Server?

You can run the SQL Profiler, and filter by CPU or Duration so that you're excluding all the "small stuff". Then it should be a lot easier to determine if you have a problem like a specific stored proc that is running much longer than it should (could be a missing index or something).

Two caveats:

  • If the problem is massive amounts of tiny transactions, then the filter I describe above would exclude them, and you'd miss this.
  • Also, if the problem is a single, massive job (like an 8-hour analysis job or a poorly designed select that has to cross-join a billion rows) then you might not see this in the profiler until it is completely done, depending on what events you're profiling (sp:completed vs sp:statementcompleted).

But normally I start with the Activity Monitor or sp_who2.

Seaborn plots not showing up

If you plot in IPython console (where you can't use %matplotlib inline) instead of Jupyter notebook, and don't want to run plt.show() repeatedly, you can start IPython console with ipython --pylab:

$ ipython --pylab     
Python 3.6.6 |Anaconda custom (64-bit)| (default, Jun 28 2018, 17:14:51) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.0.1 -- An enhanced Interactive Python. Type '?' for help.
Using matplotlib backend: Qt5Agg

In [1]: import seaborn as sns

In [2]: tips = sns.load_dataset("tips")

In [3]: sns.relplot(x="total_bill", y="tip", data=tips) # you can see the plot now

How generate unique Integers based on GUIDs

A GUID is a 128 bit integer (its just in hex rather than base 10). With .NET 4 use http://msdn.microsoft.com/en-us/library/dd268285%28v=VS.100%29.aspx like so:

// Turn a GUID into a string and strip out the '-' characters.
BigInteger huge = BigInteger.Parse(modifiedGuidString, NumberStyles.AllowHexSpecifier)

If you don't have .NET 4 you can look at IntX or Solver Foundation.

Terminating idle mysql connections

I don't see any problem, unless you are not managing them using a connection pool.

If you use connection pool, these connections are re-used instead of initiating new connections. so basically, leaving open connections and re-use them it is less problematic than re-creating them each time.

AngularJS: How can I pass variables between controllers?

There are two ways to do this

1) Use get/set service

2) $scope.$emit('key', {data: value}); //to set the value

 $rootScope.$on('key', function (event, data) {}); // to get the value

How to decrypt the password generated by wordpress

You will not be able to retrieve a plain text password from wordpress.

Wordpress use a 1 way encryption to store the passwords using a variation of md5. There is no way to reverse this.

See this article for more info http://wordpress.org/support/topic/how-is-the-user-password-encrypted-wp_hash_password

m2eclipse error

I had same problem with Eclipse 3.7.2 (Indigo) and maven 3.0.4.

In my case, the problem was caused by missing maven-resources-plugin-2.4.3.jar in {user.home}\.m2\repository\org\apache\maven\plugins\maven-resources-plugin\2.4.3 folder. (no idea why maven didn't update it)

Solution:

1.) add dependency to pom.xml

<dependency>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-resources-plugin</artifactId>
    <version>2.4.3</version>
</dependency>

2.) run mvn install from Eclipse or from command line

3.) refresh the project in eclipse (F5)

4.) run Maven > Update Project Configuration... on project (right click)

JAR file is downloaded to local repository and there are no errors in WS.

How to get the last N rows of a pandas DataFrame?

How to get the last N rows of a pandas DataFrame?

If you are slicing by position, __getitem__ (i.e., slicing with[]) works well, and is the most succinct solution I've found for this problem.

pd.__version__
# '0.24.2'

df = pd.DataFrame({'A': list('aaabbbbc'), 'B': np.arange(1, 9)})
df

   A  B
0  a  1
1  a  2
2  a  3
3  b  4
4  b  5
5  b  6
6  b  7
7  c  8

df[-3:]

   A  B
5  b  6
6  b  7
7  c  8

This is the same as calling df.iloc[-3:], for instance (iloc internally delegates to __getitem__).


As an aside, if you want to find the last N rows for each group, use groupby and GroupBy.tail:

df.groupby('A').tail(2)

   A  B
1  a  2
2  a  3
5  b  6
6  b  7
7  c  8

How do I assign a null value to a variable in PowerShell?

If the goal simply is to list all computer objects with an empty description attribute try this

import-module activedirectory  
$domain = "domain.example.com" 
Get-ADComputer -Filter '*' -Properties Description | where { $_.Description -eq $null }

MYSQL: How to copy an entire row from one table to another in mysql with the second table having one extra column?

To refine the answer from Zed, and to answer your comment:

INSERT INTO dues_storage
SELECT d.*, CURRENT_DATE()
FROM dues d
WHERE id = 5;

See T.J. Crowder's comment

HTTP Basic Authentication credentials passed in URL and encryption

Yes, it will be encrypted.

You'll understand it if you simply check what happens behind the scenes.

  1. The browser or application will first break down the URL and try to get the IP of the host using a DNS Query. ie: A DNS request will be made to find the IP address of the domain (www.example.com). Please note that no other information will be sent via this request.
  2. The browser or application will initiate a SSL connection with the IP address received from the DNS request. Certificates will be exchanged and this happens at the transport level. No application level information will be transferred at this point. Remember that the Basic authentication is part of HTTP and HTTP is an application level protocol. Not a transport layer task.
  3. After establishing the SSL connection, now the necessary data will be passed to the server. ie: The path or the URL, the parameters and basic authentication username and password.

Spring Hibernate - Could not obtain transaction-synchronized Session for current thread

My configuration was like this. I had a QuartzJob , a Service Bean , and Dao . as usual it was configured with LocalSessionFactoryBean (for hibernate) , and SchedulerFactoryBean for Quartz framework. while writing the Quartz job , I by mistake annotated it with @Service , I should not have done that because I was using another strategy to wire the QuartzBean using AutowiringSpringBeanJobFactory extending SpringBeanJobFactory.

So what actually was happening is that due to Quartz Autowire , TX was getting injected to the Job Bean and at the same time Tx Context was set by virtue of @Service annotation and hence the TX was falling out of sync !!

I hope it help to those for whom above solutions really didn't solved the issue. I was using Spring 4.2.5 and Hibernate 4.0.1 ,

I see that in this thread there is a unnecessary suggestion to add @Transactional annotation to the DAO(@Repository) , that is a useless suggestion cause @Repository has all what it needs to have don't have to specially set that @transactional on DAOs , as the DAOs are called from the services which have already being injected by @Trasancational . I hope this might be helpful people who are using Quartz , Spring and Hibernate together.

Spring boot - configure EntityManager

Hmmm you can find lot of examples for configuring spring framework. Anyways here is a sample

@Configuration
@Import({PersistenceConfig.class})
@ComponentScan(basePackageClasses = { 
    ServiceMarker.class,
    RepositoryMarker.class }
)
public class AppConfig {

}

PersistenceConfig

@Configuration
@PropertySource(value = { "classpath:database/jdbc.properties" })
@EnableTransactionManagement
public class PersistenceConfig {

    private static final String PROPERTY_NAME_HIBERNATE_DIALECT = "hibernate.dialect";
    private static final String PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH = "hibernate.max_fetch_depth";
    private static final String PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE = "hibernate.jdbc.fetch_size";
    private static final String PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE = "hibernate.jdbc.batch_size";
    private static final String PROPERTY_NAME_HIBERNATE_SHOW_SQL = "hibernate.show_sql";
    private static final String[] ENTITYMANAGER_PACKAGES_TO_SCAN = {"a.b.c.entities", "a.b.c.converters"};

    @Autowired
    private Environment env;

     @Bean(destroyMethod = "close")
     public DataSource dataSource() {
         BasicDataSource dataSource = new BasicDataSource();
         dataSource.setDriverClassName(env.getProperty("jdbc.driverClassName"));
         dataSource.setUrl(env.getProperty("jdbc.url"));
         dataSource.setUsername(env.getProperty("jdbc.username"));
         dataSource.setPassword(env.getProperty("jdbc.password"));
         return dataSource;
     }

     @Bean
     public JpaTransactionManager jpaTransactionManager() {
         JpaTransactionManager transactionManager = new JpaTransactionManager();
         transactionManager.setEntityManagerFactory(entityManagerFactoryBean().getObject());
         return transactionManager;
     }

    private HibernateJpaVendorAdapter vendorAdaptor() {
         HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
         vendorAdapter.setShowSql(true);
         return vendorAdapter;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean() {

         LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
         entityManagerFactoryBean.setJpaVendorAdapter(vendorAdaptor());
         entityManagerFactoryBean.setDataSource(dataSource());
         entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistenceProvider.class);
         entityManagerFactoryBean.setPackagesToScan(ENTITYMANAGER_PACKAGES_TO_SCAN);             
         entityManagerFactoryBean.setJpaProperties(jpaHibernateProperties());

         return entityManagerFactoryBean;
     }

     private Properties jpaHibernateProperties() {

         Properties properties = new Properties();

         properties.put(PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH, env.getProperty(PROPERTY_NAME_HIBERNATE_MAX_FETCH_DEPTH));
         properties.put(PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE, env.getProperty(PROPERTY_NAME_HIBERNATE_JDBC_FETCH_SIZE));
         properties.put(PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE, env.getProperty(PROPERTY_NAME_HIBERNATE_JDBC_BATCH_SIZE));
         properties.put(PROPERTY_NAME_HIBERNATE_SHOW_SQL, env.getProperty(PROPERTY_NAME_HIBERNATE_SHOW_SQL));

         properties.put(AvailableSettings.SCHEMA_GEN_DATABASE_ACTION, "none");
         properties.put(AvailableSettings.USE_CLASS_ENHANCER, "false");      
         return properties;       
     }

}

Main

public static void main(String[] args) { 
    try (GenericApplicationContext springContext = new AnnotationConfigApplicationContext(AppConfig.class)) {
        MyService myService = springContext.getBean(MyServiceImpl.class);
        try {
            myService.handleProcess(fromDate, toDate);
        } catch (Exception e) {
            logger.error("Exception occurs", e);
            myService.handleException(fromDate, toDate, e);
        }
    } catch (Exception e) {
        logger.error("Exception occurs in loading Spring context: ", e);
    }
}

MyService

@Service
public class MyServiceImpl implements MyService {

    @Inject
    private MyDao myDao;

    @Override
    public void handleProcess(String fromDate, String toDate) {
        List<Student> myList = myDao.select(fromDate, toDate);
    }
}

MyDaoImpl

@Repository
@Transactional
public class MyDaoImpl implements MyDao {

    @PersistenceContext
    private EntityManager entityManager;

    public Student select(String fromDate, String toDate){

        TypedQuery<Student> query = entityManager.createNamedQuery("Student.findByKey", Student.class);
        query.setParameter("fromDate", fromDate);
        query.setParameter("toDate", toDate);
        List<Student> list = query.getResultList();
        return CollectionUtils.isEmpty(list) ? null : list;
    }

}

Assuming maven project: Properties file should be in src/main/resources/database folder

jdbc.properties file

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=your db url
jdbc.username=your Username
jdbc.password=Your password

hibernate.max_fetch_depth = 3
hibernate.jdbc.fetch_size = 50
hibernate.jdbc.batch_size = 10
hibernate.show_sql = true

ServiceMarker and RepositoryMarker are just empty interfaces in your service or repository impl package.

Let's say you have package name a.b.c.service.impl. MyServiceImpl is in this package and so is ServiceMarker.

public interface ServiceMarker {

}

Same for repository marker. Let's say you have a.b.c.repository.impl or a.b.c.dao.impl package name. Then MyDaoImpl is in this this package and also Repositorymarker

public interface RepositoryMarker {

}

a.b.c.entities.Student

//dummy class and dummy query
@Entity
@NamedQueries({
@NamedQuery(name="Student.findByKey", query="select s from Student s where s.fromDate=:fromDate" and s.toDate = :toDate)
})
public class Student implements Serializable {

    private LocalDateTime fromDate;
    private LocalDateTime toDate;

    //getters setters

}

a.b.c.converters

@Converter(autoApply = true)
public class LocalDateTimeConverter implements AttributeConverter<LocalDateTime, Timestamp> {

    @Override
    public Timestamp convertToDatabaseColumn(LocalDateTime dateTime) {

        if (dateTime == null) {
            return null;
        }
        return Timestamp.valueOf(dateTime);
    }

    @Override
    public LocalDateTime convertToEntityAttribute(Timestamp timestamp) {

        if (timestamp == null) {
            return null;
        }    
        return timestamp.toLocalDateTime();
    }
}

pom.xml

<properties>
    <java-version>1.8</java-version>
    <org.springframework-version>4.2.1.RELEASE</org.springframework-version>
    <hibernate-entitymanager.version>5.0.2.Final</hibernate-entitymanager.version>
    <commons-dbcp2.version>2.1.1</commons-dbcp2.version>
    <mysql-connector-java.version>5.1.36</mysql-connector-java.version>
     <junit.version>4.12</junit.version> 
</properties>

<dependencies>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>${junit.version}</version>
        <scope>test</scope>
    </dependency>

    <!-- Spring -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>

    <dependency>
        <groupId>javax.inject</groupId>
        <artifactId>javax.inject</artifactId>
        <version>1</version>
        <scope>compile</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>${org.springframework-version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${org.springframework-version}</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${hibernate-entitymanager.version}</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql-connector-java.version}</version>
    </dependency>

    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-dbcp2</artifactId>
        <version>${commons-dbcp2.version}</version>
    </dependency>
</dependencies>

<build>
     <finalName>${project.artifactId}</finalName>
     <plugins>
         <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.3</version>
            <configuration>
                <source>${java-version}</source>
                <target>${java-version}</target>
                <compilerArgument>-Xlint:all</compilerArgument>
                <showWarnings>true</showWarnings>
                <showDeprecation>true</showDeprecation>
            </configuration>
        </plugin>
     </plugins>
</build>

Hope it helps. Thanks

Entry point for Java applications: main(), init(), or run()?

This is a peculiar question because it's not supposed to be a matter of choice.

When you launch the JVM, you specify a class to run, and it is the main() of this class where your program starts.

By init(), I assume you mean the JApplet method. When an applet is launched in the browser, the init() method of the specified applet is executed as the first order of business.

By run(), I assume you mean the method of Runnable. This is the method invoked when a new thread is started.

  • main: program start
  • init: applet start
  • run: thread start

If Eclipse is running your run() method even though you have no main(), then it is doing something peculiar and non-standard, but not infeasible. Perhaps you should post a sample class that you've been running this way.

How to enable PHP short tags?

If you are using xampp in windows then please do following

  1. Open XAMPP control panel.
  2. Click on CONFIG button.
  3. Go to PHP (php.ini) option.

Find short_open_tag using ctrl+f utility

You will found ;short_open_tag

kindly remove the semicolon (;) from line.

and keep it as short_open_tag = on

Finally, restart your Apache server

Example of Mockito's argumentCaptor

The steps in order to make a full check are:

Prepare the captor :

ArgumentCaptor<SomeArgumentClass> someArgumentCaptor = ArgumentCaptor.forClass(SomeArgumentClass.class);

verify the call to dependent on component (collaborator of subject under test). times(1) is the default value, so ne need to add it.

verify(dependentOnComponent, times(1)).send(someArgumentCaptor.capture());

Get the argument passed to collaborator

SomeArgumentClass someArgument = messageCaptor.getValue();

someArgument can be used for assertions

PHP prepend leading zero before single digit number, on-the-fly

You can use str_pad for adding 0's

str_pad($month, 2, '0', STR_PAD_LEFT); 

string str_pad ( string $input , int $pad_length [, string $pad_string = " " [, int $pad_type = STR_PAD_RIGHT ]] )

How to add text to an existing div with jquery

Your html is invalid button is not a null tag. Try

<div id="Content">
   <button id="Add">Add</button>
</div> 

Check if MySQL table exists or not

Taken from another post

$checktable = mysql_query("SHOW TABLES LIKE '$this_table'");
$table_exists = mysql_num_rows($checktable) > 0;

Check if String / Record exists in DataTable

You can loop over each row of the DataTable and check the value.

I'm a big fan of using a foreach loop when using IEnumerables. Makes it very simple and clean to look at or process each row

DataTable dtPs = // ... initialize your DataTable
foreach (DataRow dr in dtPs.Rows)
{
    if (dr["item_manuf_id"].ToString() == "some value")
    {
        // do your deed
    }
}

Alternatively you can use a PrimaryKey for your DataTable. This helps in various ways, but you often need to define one before you can use it.

An example of using one if at http://msdn.microsoft.com/en-us/library/z24kefs8(v=vs.80).aspx

DataTable workTable = new DataTable("Customers");

// set constraints on the primary key
DataColumn workCol = workTable.Columns.Add("CustID", typeof(Int32));
workCol.AllowDBNull = false;
workCol.Unique = true;

workTable.Columns.Add("CustLName", typeof(String));
workTable.Columns.Add("CustFName", typeof(String));
workTable.Columns.Add("Purchases", typeof(Double));

// set primary key
workTable.PrimaryKey = new DataColumn[] { workTable.Columns["CustID"] };

Once you have a primary key defined and data populated, you can use the Find(...) method to get the rows that match your primary key.

Take a look at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx

DataRow drFound = dtPs.Rows.Find("some value");
if (drFound["item_manuf_id"].ToString() == "some value")
{
    // do your deed
}

Finally, you can use the Select() method to find data within a DataTable also found at at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx.

String sExpression = "item_manuf_id == 'some value'";
DataRow[] drFound;
drFound = dtPs.Select(sExpression);

foreach (DataRow dr in drFound)
{
    // do you deed. Each record here was already found to match your criteria
}

Hiding a button in Javascript

Something like this should remove it

document.getElementById('x').style.visibility='hidden';

If you are going to do alot of this dom manipulation might be worth looking at jquery

Convert an NSURL to an NSString

You can use any one way

NSString *string=[NSString stringWithFormat:@"%@",url1];

or

NSString *str=[url1 absoluteString];

NSLog(@"string :: %@",string);

string :: file:///var/containers/Bundle/Application/E2D7570B-D5A6-45A0-8EAAA1F7476071FE/RemoDuplicateMedia.app/loading_circle_animation.gif

NSLog(@"str :: %@", str);

str :: file:///var/containers/Bundle/Application/E2D7570B-D5A6-45A0-8EAA-A1F7476071FE/RemoDuplicateMedia.app/loading_circle_animation.gif

WHERE clause on SQL Server "Text" data type

Another option would be:

SELECT * FROM [Village] WHERE PATINDEX('foo', [CastleType]) <> 0

Escaping special characters in Java Regular Expressions

Use this Utility function escapeQuotes() in order to escape strings in between Groups and Sets of a RegualrExpression.

List of Regex Literals to escape <([{\^-=$!|]})?*+.>

public class RegexUtils {
    static String escapeChars = "\\.?![]{}()<>*+-=^$|";
    public static String escapeQuotes(String str) {
        if(str != null && str.length() > 0) {
            return str.replaceAll("[\\W]", "\\\\$0"); // \W designates non-word characters
        }
        return "";
    }
}

From the Pattern class the backslash character ('\') serves to introduce escaped constructs. The string literal "\(hello\)" is illegal and leads to a compile-time error; in order to match the string (hello) the string literal "\\(hello\\)" must be used.

Example: String to be matched (hello) and the regex with a group is (\(hello\)). Form here you only need to escape matched string as shown below. Test Regex online

public static void main(String[] args) {
    String matched = "(hello)", regexExpGrup = "(" + escapeQuotes(matched) + ")";
    System.out.println("Regex : "+ regexExpGrup); // (\(hello\))
}

Unsigned keyword in C++

From the link above:

Several of these types can be modified using the keywords signed, unsigned, short, and long. When one of these type modifiers is used by itself, a data type of int is assumed

This means that you can assume the author is using ints.