Unsupported major.minor version 51.0

Today I faced with the following exception:

java.lang.UnsupportedClassVersionError: com/rdiachenko/blackbox/alg/InsertionSortTest : Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClass(RemoteTestRunner.java:693)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.loadClasses(RemoteTestRunner.java:429)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

Reason: Java sources were compiled with JDK 7, but were running on the lower JDK 6.
Solution: use higher (or the same) JDK during runtime and lower (or the same) during compile time.

Verstion 51.0 in exception message means J2SE 7. Here the list of all versions: http://en.wikipedia.org/wiki/Java_class_file

JavaScript plugin for Eclipse

Found a nice plugin for Eclipse which provides a pretty handy work with JavaScript - VJET.

VJET JavaScript IDE is an Eclipse plugin that provides a fully integrated development environment for JavaScript. Its main features:

- Code Assistance
- Code Search
- Syntax and Semantic Checking
- Type Declarations using VJETDoc
- Execution/Debugging

The project's site is here: http://www.eclipse.org/vjet/
The update site is here: http://www.eclipse.org/vjet/download/

Install and run Windows applications on Fedora/Ubuntu

PlayOnLinux is a tool which allows to install/run Windows applications under Linux. It is a kind of shell for wine.

Installation for Fedora:

$ wget http://rpm.playonlinux.com/playonlinux.repo
$ sudo cp  playonlinux.repo /etc/yum.repos.d/
$ sudo yum install playonlinux

Installation for Ubuntu here