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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.

Java Topic / Java tutorial The method overloading and method overriding are two different ways of achieving polymorphism. Both of them are very useful concepts required to solve the programming problems.

Does it all make sense now? Do you know how to solve every problem? Probably not, but when it comes right down to it, using Java EE can be even simpler than using Spring, and take much less time. You just have to find the right guides and the right documentation (which is admittedly a severe sore-spot of Java EE; the documentation is still a work in progress, but is getting much better, save blogs like this one.) You have to turn to a vendor like JBoss, or IBM in order to get the use-case driven documentation you need, and they do have documentation, it's just a matter of finding it. Seam 3 in particular strives to give extensive user-documentation, hopefully making things much simpler to adopt, and easier to extend. The main purpose of this article was not to bash Spring, although I may have taken that tone on occasion just for contrast and a little bit of fun. Both Spring and Java EE are strongly engineered and have strong foundations in practical use, but if you want a clean programming experience right out of the box - use Java EE 6 on JBoss Application Server 6 - JBoss Tools - and Eclipse. I will say, though, that the feeling I've gotten from the Spring forums vs the Java EE forums, is that there are far many more people willing to help you work through Java EE issues, and more available developers of the frameworks themselves to actually help you than there are on the Spring side. The community for Java EE is much larger, and much more supportive (from my personal experience.) In the end, I did get my application migrated successfully, and despite these issues (from which I learned a great deal,) I am still happy with Java EE, and would not go back to Spring! But I do look forward to further enhancements from the JBoss Seam project, which continue to make developing for Java EE simpler and more fun. Don't believe me? Try it out. Find something wrong? Tell me. Want more? Let me know what you want to hear.

The Apache Software Foundation has resigned its seat on the Java SE/EE Executive Committee. Apache has served on the EC for the past 10 years, winning the JCP "Member of the Year" award 4 times, and recently was ratified for another term with support from 95% of the voting community. Further, the project communities of the ASF, home to Apache Tomcat, Ant, Xerces, Geronimo, Velocity and nearly a 100 mainstay java components have implemented countless JSRs and serve on and contribute to many of the JCPs technical expert groups. We'd like to provide some explanation to the community as to why we're taking this significant step.