Installing this is very simple. Just drag and drop the icon in your running eclipse (Juno)
Hope this link still work works : –
http://marketplace.eclipse.org/content/jadclipse-eclipse-4x#.UZH7YKJHI1N
JadClipse for Eclipse 4.x also support Eclipse 3.x, and provides several new features:
1. Integrate jad.exe into the plugin, don’t need to set jad path in the preference page again.
2. Add two options in the JadClipse main preference page:
(1) Use Eclipse member sorter
(2) Show decompiler report
3. Update the formatting preference default settings, the “Output fields before methods” setting’s default value changes to true.