Tutorial by Examples: i

CF keeps you logged in. I sometimes have to switch between regions and don't always know where I am #Where am I? cf target #Login. This is logging in to the UK region of bluemix. Replace eu-gb with ng to go to the US. cf login -a https://api.eu-gb.bluemix.net #List spaces cf spaces #C...

The If control statement allows different code to be executed depending upon the evaluation of a conditional (Boolean) statement. A conditional statement is one that evaluates to either True or False, e.g. x > 2. There are three patterns that can be used when implementing an If statement, which ...

This is the simplest way to connect. First, the driver has to be registered with java.sql.DriverManager so that it knows which class to use. This is done by loading the driver class, typically with java.lang.Class.forname(<driver class name>). /** * Connect to a PostgreSQL database. *...

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...

CDI is a Java EE specification. It specifies how things should be done, and which features must be provided, but it isn't actually a specific library or set of code. In order to use CDI, you will need to use a CDI implementation. The reference implementation of the CDI spec is a set of libraries kn...

You can install Solr in any system where a suitable Java Runtime Environment (JRE) is available, as detailed below. Currently this includes Linux, OS X, and Microsoft Windows. You will need the Java Runtime Environment (JRE) version 1.8 or higher. At a command line, check your Java version like thi...

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...

Given the following class: public class FinalizableObject { public FinalizableObject() { Console.WriteLine("Instance initialized"); } ~FinalizableObject() { Console.WriteLine("Instance finalized"); } } A program that create...

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 common case for injecting dependencies into a class is with constructor injection. This involves annotating a constructor on the class with @Inject. The CDI manager will look for a constructor with the @Inject annotation when creating an instance of the class. When it finds an @Inject-annotated ...

Server Side example Create Listener for server Start of with creating an server that will handle clients that connect, and requests that will be send. So create an Listener Class that will handle this. class Listener { public Socket ListenerSocket; //This is the socket that will listen ...

A MultiTrigger is similar to a standard Trigger in that it only applies to properties within the same control. The difference is that a MultiTrigger has multiple conditions which must be satisfied before the trigger will operate. Conditions are defined using the <Condition> tag. <TextBlock...

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_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...

@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...