Java APIs

hi all,
I'm new to java programming and trying fix jedit in my ubuntu box, but it seems my efforts are going ... fultile.

First my config -
neo@tathagata:~$ java -version
java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode, sharing)

now when I issue the command jedit I get
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/gjt/sp/jedit/jEdit (Unsupported major.minor version 48.0)
at java.lang.ClassLoader.defineClass0(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:488)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:106)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:243)
at java.net.URLClassLoader.access$100(URLClassLoader.java:51)
at java.net.URLClassLoader$1.run(URLClassLoader.java:190)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:183)
at java.lang.ClassLoader.loadClass(ClassLoader.java:294)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:288)
at java.lang.ClassLoader.loadClass(ClassLoader.java:250)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:310)

can the version of jdk I'm using create any problem?
When I'm saying JAVA 2 version 1.4 I'm refering to the VM .. right? so should jdk be a concern?
I'm new to java ...and if things dont get fixed I would need to go back to windows leaving ubuntu ... please help
Thanks in advance..