Why Patterns Are Important A pattern is a proven solution to a software problem enabling reuse of software at the design level. The purpose of a pattern is to conceptually pair a problem with its design solution and then apply the solution to similar problems. Code-level reuse of software is desirable, but design-level reuse is far more flexible. Patterns are one of the greatest resources you will have in the design of object-oriented software. They will definitely help you to master the Java programming language, be more productive, and develop effective Java solutions. Building Patterns with Design Principles At the core of any pattern is a collection of design principles. This section looks at a simple and unconventional approach to building patterns from the ground up. The approach is to start with a simple design and gradually make changes so the design is more flexible. Each step uses the object-oriented tools available to you in Java, as well as one or more of the design principles discussed in the previous section. Each design change becomes a step in building more complex design patterns. By following the exercises in this section, it will be clear how applying design principles makes software…

  Language Features Added in Java 5   Several useful syntactic elements were introduced in Java 5. All these features are supported by an updated compiler, and all translate to already defined Java bytecode, meaning that virtual machines can execute these features with no need for an update: ❑ Generics: A way to make classes type-safe that are written to work on any arbitrary object type, such as narrowing an instance of a collection to hold a specific object type and eliminating the need to cast objects when taking an object out of the collection. ❑ Enhanced for loop: Acleaner and less error-prone version of the for loop for use with iterators. ❑ Variable arguments: Support for passing an arbitrary number of parameters to a method. ❑ Boxing/unboxing: Direct language support for automatic conversion between primitive types and their reference types (such as int and Integer). ❑ Type-safe enumerations: Clean syntax for defining and using enumerations, supported at the language level. ❑ Static import: Ability to access static members from a class without need to qualify them with a class name. ❑ Metadata: Coupled with new tools developed by third-party companies, saves developers the effort of writing boilerplate code by…

Runtime Technologies  This section provides a brief description of the runtime technologies. Runtime technologies are used to run the application after it is deployed, versus development tools, which are used to develop the application. Figure 1.1 provides a visual representation of how these technologies fit together to provide a complete runtime solution.   Java Platform, Standard Edition (Java SE) Development Kit (JDK) We will use the latest version of the JDK (for example, 1.5) available from the java.sun.com website. Note that as long as we have JDK 1.4 or later, the technologies covered in this book (Hibernate and Spring, for example) will work just fine. The Spring Framework (springframework.org) The Spring Framework contains a large number of classes and packages, but it is designed as a modular framework that can be phased gradually into a project by using only the features needed (for example, web framework). Spring complements Java/JEE by providing an Inversion of Control (IoC) container (explained later in book), a web framework, a transaction management abstraction layer, JDBC helper classes, job scheduling APIs, email capabilities, and more. Spring has been around since 2002 and has gained considerable momentum and support from the community, including commercial vendors such as…

Using the Admin Portlet Liferay provides a useful application called Admin that helps you perform several administrative tasks. Such tasks involve monitoring resource utilization to ensure optimal portal performance, logging messages from various classes in the system to get insight into what’s happening under the hood, checking the various system and portal properties, monitoring server instances, shutting down the server, and so on. You will now learn to use the Admin portlet. First, you need to install this portlet on your ISI portal. For this, you will create a private page in your own community. Users without administrator privileges will not be able to use the portlet, but it’s still a good idea to put it on a private page rather than a public page. Perform these steps to create a private page: 325 1. Log on to the portal using your Administrator account. 2. Open the drop-down Welcome menu. 3. Navigate to the Private Pages menu item of the Fundamental Analysts community that you created previously 4. Click the new-page icon on the right side of the menu item This opens the Manage Pages screen, which lets you create a new page 5. Enter Administration as the page name.…