Funny enough this works on some machines (Window XP and Windows 7 32bits systems) but I don't know if it's because I have Window 7 64 bits system. Also,I read a documentation on oracle.com about installation of JDK 7 and it says that you have to add the bin directory to the path variable.
Instruction below.
To set the PATH variable permanently, add the full path of the jdk1.7.0\bin directory to the PATH variable. Typically, this full path looks something like C:\Program Files\Java\jdk1.7.0\bin. Set the PATH variable as follows on Microsoft Windows:
1. Click Start, then Control Panel, then System.
2. Click Advanced, then Environment Variables.
3. Add the location of the bin folder of the JDK installation for the PATH variable in System Variables. The following is a typical value for the PATH variable:
C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.7.0\bin
Note:
• The PATH environment variable is a series of directories separated by semicolons (;) and is not case-sensitive. Microsoft Windows looks for programs in the PATH directories in order, from left to right.
•
You should only have one bin directory for a JDK in the path at a time. Those following the first instance are ignored.
• If you are not sure where to add the path, add it to the right of the value of the PATH variable.
• The new path takes effect in each new command window you open after setting the PATH variable.
Excerpt from java tutorials
It looks like the bin folder contains all the applications needed to run java on any machine (see the java installation folder). I don't know what is really wrong. The system recognises java and even compiles correctly but it just won't run.