Install Java Decompiler in Rational Application Developer (WCS).

1.Download the JAD file from the following links.

http://www.softpedia.com/get/Programming/Debuggers-Decompilers-Dissasemblers/JAD.shtml

http://www.varaneckas.com/jad

2.Download the JAD eclipse plugin from the following site.

https://sourceforge.net/projects/jadclipse/

The download file name should be "(net.sf.jadclipse_x.x.x.jar)".

3.Copy the plugin JAR "(net.sf.jadclipse_x.x.x.jar)" and place it in the RAD installed Path "C:\IBM\SDP8\plugins".
4.Restart the RAD
5.After the restart the new JadClipse option will be available in the prefences.

For that:
Click Windows> Preferences>Java then click the JadClipse option, in right side has the option for  Path To Decompiler.

There, we have to specify the JAD file path (Downloaded file in Step 1)
"\C:\IBM\SDP8\jadnt158\jad.exe"