I installed eclipse galileo a long time back and used pydev plug-in for development.
i wanted to install the java plug-in for but could not install it.

My friend gave me his eclipse folder (eclipse helios) which contained the java plug-ins, i thought copying those plug-ins to the /usr/lib/eclipse/plugins directory and assumed that it would work.
though it did, but my eclipse galileo was now eclipse helios and took really very long time to startup.

I completely removed the eclipse and other dependencies using synaptic. (also deleted all the plug-in files from the /usr/lib/elcipse/plugin directory).

I reinstalled eclipse and now on starting eclipse i get the following error.

the error msg tells me to view the error log file in the /usr/lib/eclipse/configuration/xxxxxx.log

!SESSION Wed Mar 02 06:15:13 IST 2011 ------------------------------------------
!ENTRY org.eclipse.equinox.launcher 4 0 2011-03-02 06:15:13.516
!MESSAGE Exception launching the Eclipse Platform:
!STACK
java.lang.ClassNotFoundException: org.eclipse.core.runtime.adaptor.EclipseStarter
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:556)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)


Can somebody help me on resolving this error ?

Thank you.

I'd say, install eclipse-jdt and javahelper

eclipse-jdt is already installed.
i installed javahelper but the problem persists.
still there is a log file created with same error message.