Tutorial by Examples: d

Instead of specifying connection parameters like user and password (see a complete list here) in the URL or a separate parameters, you can pack them into a java.util.Properties object: /** * Connect to a PostgreSQL database. * @param url the JDBC URL to connect to. Must start with "jdbc:...

It is common to use javax.sql.DataSource with JNDI in application server containers, where you register a data source under a name and look it up whenever you need a connection. This is code that demonstrates how data sources work: /** * Create a data source with connection pool for PostgreSQL c...

You can start Solr by running bin/solr from the Solr directory and this will start Solr in the background, listening on port 8983. $ bin/solr start To change the port Solr listens on, you can use the -p parameter when starting, such as: $ bin/solr start -p 8984 Since Solr is a server, it is more...

Rule of thumb: when garbage collection occurs, "live objects" are those still in use, while "dead objects" are those no longer used (any variable or field referencing them, if any, has gone out of scope before the collection occurs). In the following example (for convenience, Fi...

What if two (or several) otherwise dead objects reference one another? This is shown in the example below, supposing that OtherObject is a public property of FinalizableObject: var obj1 = new FinalizableObject1(); var obj2 = new FinalizableObject2(); obj1.OtherObject = obj2; obj2.OtherObject = ...

Implement Dispose() method (and declare the containing class as IDisposable) as a means to ensure any memory-heavy resources are freed as soon as the object is no longer used. The "catch" is that there is no strong guarantee the the Dispose() method would ever be invoked (unlike finalizers...

As Dispose() and finalizers are aimed to different purposes, a class managing external memory-heavy resources should implement both of them. The consequence is writing the class so that it handles well two possible scenarios: When only the finalizer is invoked When Dispose() is invoked first and...

The same example from above can also be done using what is known as field injection. Instead of annotating the constructor with @Inject, we annotate the fields we wish to have injected public class Spaceship { @Inject private PropulsionSystem propulsionSystem; @Inject private ...

WP_DEBUG_LOG is a companion to WP_DEBUG that causes all errors to also be saved to a debug.log log file inside the /wp-content/ directory. This is useful if you want to review all notices later or need to view notices generated off-screen (e.g. during an AJAX request or wp-cron run). //enable defi...

WP_DEBUG_DISPLAY is another companion to WP_DEBUG that controls whether debug messages are shown inside the HTML of pages or not. The default is 'true' which shows errors and warnings as they are generated. Setting this to false will hide all errors. This should be used in conjunction with WP_DEBUG_...

Example of how to calculate the output shape and overcome the difficulties of using tf.nn.conv2d_transpose with unknown batch size (when input.get_shape() is (?, H, W, C) or (?, C, H, W)). def upconvolution (input, output_channel_size, filter_size_h, filter_size_w, stride_h, str...

public class DependentScopedClass { //This class has no scoping annotations, so a new instance gets created at every injection point. @Inject public DependentScopedClass(SomeDependency someDependency) { doSomethingWith(someDependency); } } The default scope for...

@RequestScoped public class RequestScopedClass { //This class gets constructed once per Servlet request, and is shared among all CDI-managed classes within that request. @Inject public RequestScopedClass(SomeDependency someDependency) { doSomethingWith(someDependency); ...

@ApplicationScoped public class ApplicationScopedClass { //This class gets constructed once for the entire life of the application, and is shared among all CDI-managed classes throughout the life of the application. @Inject public ApplicationScopedClass(SomeDependency someDependenc...

@SessionScoped public class SessionScopedClass implements Serializable { //This class gets constructed once per session, and is shared among all CDI-managed classes within that session. Notice that it implements Serializable, since the instance will get put on the session. @Inject ...

SCRIPT_DEBUG is a related constant that will force WordPress to use the "dev" versions of core CSS and JavaScript files rather than the minified versions that are normally loaded. This is useful when you are testing modifications to any built-in .js or .css files. Default is false. //enab...

The following code, inserted in your wp-config.php file, will log all errors, notices, and warnings to a file called debug.log in the wp-content directory. It will also hide the errors so they do not interrupt page generation. // Enable WP_DEBUG mode define( 'WP_DEBUG', true ); // Enable Debug...

Add the rx-android dependency as well as a current version of rx-java to the build.gradle. Because RxAndroid releases are few and far between, it is recommended you also explicitly depend on RxJava's latest version for bug fixes and new features. Rx1 compile 'io.reactivex:rxandroid:1.2.1' co...

:wqall Exiting multiple files with saving contents :qall! Exiting multiple files without saving contents

Once you have installed Visual Studio from https://www.visualstudio.com/downloads/, start a new project. Select 'Windows Forms Application' from Visual Basic Tab. You can rename it here if you need to. Once you click 'OK', you will see this window: Click on the 'Toolbo...