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"Since 1994, the Java programming language evolved and became a valid tool to develop reliable and performant server applications as opposed to just applets and client applications. The major disadvantage of the Java platform is that still today the only portable way to start a Java application relies on a single point of entry: the public static void main(String[]) method. Having a single-point of entry is a valid solution for client applications, where interactively a user can command to the application to quit (which can terminate the Virtual Machine process at calling the System.exit(int) method), but in those cases where the application is not interactive (server applications) there is currently no portable way to notify the Virtual Machine of its imminent shutdown. A server application written in Java might have to perform several tasks before being able to shutdown the Virtual Machine process. For example in the case of a Servlet container, before the VM process is shut down, sessions might need to be serialized to disk, and web applications need to be destroyed. One common solution to this problem is to create (for example) a ServerSocket and wait for a particular message to be issued. When the message is received, all operations required to shut down the server applications are performed and at the end the System.exit method is called to terminate the Virtual Machine process. This method however, has several disadvantages and risks: In case of a system-wide shutdown, the Virtual Machine process may be shut down directly by the operating system without notifying the running server application. If an attacker finds out the shutdown message to send to the server and discovers a way to send this message, he can easily interrupt the server's operation, bypassing all the security restrictions implemented in the operating system. Most multi-user operating systems already have a way in which server applications are started and stopped. Under Unix based

Interview Questions on Java Swing for GUI Programmer.Swing is a difficult technology to learn and for programming GUI in swing you need a bit of expertize which makes demand of Swing developer quite high and same time make interview process for swing developer quite challenging and testing. Adding to it there are not much swing interview questions available on net. This article solve this problem by providing some of the best swing interview questions asked in banks. these questions are practical , genuine and same time challenging.

Java supports two selection statements - if and switch. These statements allow us to control the flow of the program. Depending upon the expressions or values, the corresponding blocks/statements of code will be executed or by passed. The two statements are if statement is a conditional branch statement. This is a two way branch statement. Depending upon the whether a condition is true or false, the corresponding code is executed. switch statement is a multiway branch statement. Depending upon the value used for switching, the corresponding code is executed. These two statements are very powerful and are used widely across any application. They provide effective solutions for branching problems.

With AutoPatch, an agile development process that requires a database change looks like this: Developer alters the model, which requires a change to the database Developer possibly consults a DBA, and develops a SQL patch against their personal database that implements the alteration Developer commits the patch to source control at the same time as they commit their dependent code Other developers' and environments' databases are automatically updated by AutoPatch the next time the new source is run This represents streamlined environment maintenance, allowing developers to cheaply have their own databases and all databases to stay in synch with massively lower costs and no environment skew. That's what AutoPatch does. Clusters with one database? Multiple schemas? Logical migrations, instead of just DDL changes? Need to do something special/custom? Need to distribute your changes commercially? All without paying anything? No problem.

migrate4j is a database migration tool. Suppose you determine that you need a new database table for your project. If you develop alone, you could write an SQL script that adds a table and manually apply this to your development system. But if you work with other developers, or need to keep a test system in synch with your development system, this become tedious and error prone. Migration tools make it possible to add your new table (or make any other schema changes) in an automated fashion, ensuring all your systems are always in synch. Migration tools also make it possible to quickly and easily roll back previous changes. Unlike typing commands into an interactive SQL window or storing SQL scripts, migration tools keep a detailed history of how your database schema evolved (just in case you need to go back to a previous version). Finally, migration tools minimize or eliminate the problem of having to use vendor specific syntax - you may never switch database products, but if you do, using a migration tool will make your life much easier. The initial intent of migrate4j was to make a Java version of Ruby's db:migrate. If you've used db:migrate, you probably fell in love with it's simple syntax, easy configuration and ability to roll changes up and back effortlessly. The intent (and the challenge) of migrate4j is to bring the power and simplicity of db:migrate to Java programmers, using familiar type safety and syntax. Along the way, we're adding additional functionality that makes migrate4j more than just another Ruby tool rewritten for Java - it is a Java project intended to make other Java projects even better.

I think many people have the same feeling (of course including me)

XStream is a simple library to serialize objects to XML and back again. Features Ease of use. A high level facade is supplied that simplifies common use cases. No mappings required. Most objects can be serialized without need for specifying mappings. Performance. Speed and low memory footprint are a crucial part of the design, making it suitable for large object graphs or systems with high message throughput. Clean XML. No information is duplicated that can be obtained via reflection. This results in XML that is easier to read for humans and more compact than native Java serialization. Requires no modifications to objects. Serializes internal fields, including private and final. Supports non-public and inner classes. Classes are not required to have default constructor. Full object graph support. Duplicate references encountered in the object-model will be maintained. Supports circular references. Integrates with other XML APIs. By implementing an interface, XStream can serialize directly to/from any tree structure (not just XML). Customizable conversion strategies. Strategies can be registered allowing customization of how particular types are represented as XML. Error messages. When an exception occurs due to malformed XML, detailed diagnostics are provided to help isolate and fix the problem. Alternative output format. The modular design allows other output formats. XStream ships currently with JSON support and morphing.

lambdaj is a library that makes easier to address this issue by allowing to manipulate collections in a pseudo-functional and statically typed way. In our experience to iterate over collection, especially in nested loops, is often error prone and makes the code less readable. The purpose of this library is to alleviate these problems employing some functional programming techniques but without losing the static typing of java. We impose this last constraint to make refactoring easier and safer and allow the compiler to do its job.

"Executing external processes from Java is a well-known problem area. It is inheriently platform dependent and requires the developer to know and test for platform specific behaviors, for example using cmd.exe on Windows or limited buffer sizes causing deadlocks. The JRE support for this is very limited, albeit better with the new Java SE 1.5 ProcessBuilder class. Reliably executing external processes can also require knowledge of the environment variables before or after the command is executed. In J2SE 1.1-1.4 there is not support for this, since the method, System.getenv(), for retriving environment variables is deprecated. There are currently several different libraries that for their own purposes have implemented frameworks around Runtime.exec() to handle the various issues outlined above. The proposed project should aim at coordinating and learning from these initatives to create and maintain a simple, reusable and well-tested package. Since some of the more problematic platforms are not readily available, it is my hope that the broad Apache community can be a great help."

As we have just released the first milestone of the Spring Data JPA project I'd like to give you a quick introduction into its features. As you probably know, the Spring framework provides support to build a JPA based data access layer. So what does Spring Data JPA add to this base support? To answer that question I'd like to start with the data access components for a sample domain implemented using plain JPA + Spring and point out areas that leave room for improvement. After we've done that I will refactor the implementations to use the Spring Data JPA features to address these problem areas. The sample project as well as a step by step guide of the refactoring steps can be found on Github.