Thursday Aug 15, 2013

Trying Out Lambda Expressions in the Eclipse IDE

A new article, now up on otn/java, by Deepak Vohra, titled “Trying Out Lambda Expressions in the Eclipse IDE,” demonstrates how to take advantage of lambda expressions in Java SE 8 using the Eclipse IDE and virtual extension methods.

Vohra begins with the basics:
“Lambda expressions, also called closures, are a short-form replacement for anonymous classes. Lambda expressions simplify the use of interfaces that declare a single abstract method, which are also called functional interfaces. In Java SE 7, a single method interface can be implemented with one of the following options.
* Create a class that implements the interface.
* Create an anonymous class.”

Vohra explains that while lambda expressions can be used to implement a functional interface without creating a class or an anonymous class, they can be used only with interfaces that declare a single method.

Benefits of lambda expressions include:
* Concise syntax
* Method references and constructor references
* Reduced runtime overhead compared to anonymous classes

Vohra gets under the hood to explain the basics of lambda syntax, along with the nature of functional interfaces and target types, offering copious examples. All in all, the article offers a first-rate primer on how to make use of lambda expressions and virtual extension methods using the Eclipse IDE.

Check out the story here.

Tuesday May 15, 2012

JSF 2.0 for the Cloud, Part Two

Part Two of Deepak Vohra’s “JSF 2.0 for the Cloud” is now up on otn/java. In Part One, Vohra demonstrated how to take advantage of resource handling, @ManagedBean annotation, and implicit navigation. In Part Two, he explores new features in JSF 2.0 that make it ready for the cloud, including Ajax support, view parameters, preemptive navigation, event handling, and bookmarkable URLs.

Ajax support for JSF 2.0 components includes asynchronous transfer of data between a client and a server, along with partial page rendering, partial page processing, and grouping of components, and can be added using either f:ajax tag or the JSF Ajax library (jsf.js).

Regarding view parameters, Vohra explains, “JSF 2.0 added support for view parameters, which add the provision to send request parameters in a GET request. A view parameter is a UI component represented with the UIViewParameter class. Just like other UI components, it is saved in the UI component tree for a Facelets page and can be associated with validators and converters. A view parameter is an EditableValueHolder because it implements the interface.”

Preemptive navigation allows developers to determine the resource file that they  navigate to and request parameters, if needed, based on the navigation case and view parameters, thus allowing them to create a URL for JSF resources that they access from a GET request. As a result, the URL displayed shows the resource and all request parameters.

Developers should take note that plans are in the works to update Java EE 7 for “cloud-related practical considerations, such as multitenancy and elasticity, also known as horizontal scaling.” This will be available through JSR 342, which is scheduled to complete an early draft review on May 23, 2012. Specification leads are Oracle’s Bill Shannon and Linda DeMichiel.
Access the article here.

Thursday Apr 12, 2012

JavaServer Faces 2.0 for the Cloud

A new article now up on otn/java by Deepak Vohra titled “JSF 2.0 for the Cloud, Part One,” shows how JavaServer Faces 2.0 provides features ideally suited for the virtualized computing resources of the cloud. The article focuses on @ManagedBean annotation, implicit navigation, and resource handling. Vohra illustrates how the container-based model found in Java EE 7, which allows portable applications to target single machines as well as large clusters, is well suited to the cloud architecture.

From the article--

“Cloud services might not have been a factor when JavaServer Faces 2.0 (JSF 2.0) was developed, but JSF 2.0 provides features ideally suited for the cloud, for example:
•    The path-based resource handling in JSF 2.0 makes handling virtualized resources much easier and provides scalability with composite components.
•    REST-style GET requests and bookmarkable URLs in JSF 2.0 support the cloud architecture. Representational State Transfer (REST) software architecture is based on transferring the representation of resources identified by URIs. A RESTful resource or service is made available as a URI path. Resources can be accessed in various formats, such as XML, HTML, plain text, PDF, JPEG, and JSON, among others. REST offers the advantages of being simple, lightweight, and fast.
•    Ajax support in JSF 2.0 is integrable with Software as a Service (SaaS) by providing interactive browser-based Web applications.”
In Part Two of the series, Vohra will examine features such as Ajax support, view parameters, preemptive navigation, event handling, and bookmarkable URLs.

Have a look at the article here.

Thursday Aug 18, 2011

Templating with JSF 2.0 Facelets

A new article on otn/java, “Templating with JSF 2.0 Facelets,” by Deepak Vohra, offers a concise explanation of how to use Facelets, which in JavaServer Faces (JSF) 2.0, has replaced JavaServer Pages (JSP) as the default view declaration language (VDL). With Facelets, developers no longer need to configure a view handler as they once did in JSF 1.2.

From the article itself:

“Facelets is a templating framework similar to Tiles. The advantage of Facelets over Tiles is that JSF UIComponents are pre-integrated with Facelets, and Facelets does not require a Facelets configuration file, unlike Tiles, which requires a Tiles configuration file.

JSF Validators and Converters may be added to Facelets. Facelets provides a complete expression language (EL) and JavaServer Pages Standard Tag Library (JSTL) support. Templating, re-use, and ease of development are some of the advantages of using Facelets in a Web application.

In this article, we develop a Facelets Web application in Oracle Enterprise Pack for Eclipse 11g and deploy the application to Oracle WebLogic Server 11g. In the Facelets application, an input text UIComponent will be added to an input Facelets page. With JSF navigation, the input Facelets page is navigated to another Facelets page, which displays the JSF data table generated from the SQL query specified in the input Facelets page. We will use Oracle Database 11g Express Edition for the data source. Templating is demonstrated by including graphics for the header and the footer in the input and the output; the graphics have to be specified only once in the template.”

Read the complete article here.


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