Thursday Jan 19, 2012

A File I/O Tutorial Featuring NIO.2

A tutorial on the front page of otn/java titled “A File I/O Tutorial Featuring NIO.2” explains the new file I/O mechanism introduced in the Java 7 release. The java.nio.file package and its related package, java.nio.file.attribute, provide comprehensive support for file I/O and for accessing the default file system. Though the API has many classes, developers need only focus on a few key entry points. The tutorial makes it clear that the API is intuitive and easy to use.

The tutorial begins by asking, “What is a path?” and then introduces the Path class, which is the primary entry point for the package. It explains Methods in the Path class related to syntactic operations and moves on to the other primary class in the package, the Files class, which contains methods related to file operations. It then introduces some concepts common to many file operations and explains methods for checking, deleting, copying, and moving files.

The tutorial offers a concise summary of the API with suggestions for further learning.

“The java.nio.file package provides extensive support for file and file system I/O. This is a very comprehensive API, but the key entry points are as follows:
•    The Path class has methods for manipulating a path.
•    The Files class has methods for file operations, such as moving, copy, deleting, and also methods for retrieving and  setting file attributes.
•    The FileSystem class has a variety of methods for obtaining information about the file system.”

More information on NIO.2 can be found on the OpenJDK: NIO project website on java.net. This site includes resources for features provided by NIO.2 that are beyond the scope of this tutorial, such as multicasting, asynchronous I/O, and creating your own file system implementation.


Read the complete article here.

Wednesday Dec 21, 2011

Updating Java ME Applications

A new article up on otn/java, by Java ME expert Vikram Goyal, titled “Updating Java ME Applications,” demonstrates how easy it is to update the text, images, and source code for Java ME applications. Goyal explains that updating a Java ME application includes updating static data, such as text and images, as well as code components of the application. In the article, he develops a sample app that illustrates how to update an application.

As Goyal explains, “The article starts with the basics—updating simple text strings—and then moves to updating images. Finally, the article shows the easiest way to update the core application files, which Java ME makes quite easy. However, this ease can come at a price in terms of extra network traffic.”

Goyal concludes the article with some basic advice:

“If you don’t need to update the entire source code for your application, use the connection classes provided within the javax.io package, such as ContentConnection and HttpConnection, to update static data, such as text and images.

On the other hand, if you need to provide a mechanism for updating the entire source code, make sure you follow a valid update process on the server, and use platformRequest(String) with a URL that ends in jad to provide the updates. The device’s interface will then make sure the updates are applied by removing the old MIDlet and installing the new updated version.”

Read the complete article here.



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