java sun and gcj problem

[antonio giulio <antongiulio05@gmail.com>]

Hi,

I have compiled a simple java program with java sun 1.5. Everything
worked. Today I have installed eclipse, and after recompiling same
program (without errors) I have launched it but I got:

Exception in thread "main" java.lang.NoClassDefFoundError: while
resolving class: myApp
   at java.lang.VMClassLoader.transformException(java.lang.Class,
java.lang.Throwable) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.VMClassLoader.resolveClass(java.lang.Class)
(/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.initializeClass() (/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.forName(java.lang.String, boolean,
java.lang.ClassLoader) (/usr/lib/libgcj.so.6.0.0)
   at gnu.java.lang.MainThread.run() (/usr/lib/libgcj.so.6.0.0)
Caused by: java.lang.ClassNotFoundException: java.lang.StringBuilder
not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:./],
parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(java.lang.String)
(/usr/lib/libgcj.so.6.0.0)
   at java.lang.ClassLoader.loadClass(java.lang.String, boolean)
(/usr/lib/libgcj.so.6.0.0)
   at java.lang.ClassLoader.loadClass(java.lang.String)
(/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.forName(java.lang.String, boolean,
java.lang.ClassLoader) (/usr/lib/libgcj.so.6.0.0)
   ...4 more

Probably eclipse "installs & uses" gcj and not java-sun. How can I
come back to "old" situation (using java sun)?

Thanks,
Giulio