Step 1: copy the Jad.exe to the %JAVA_HOME%/jdk/bin directory.
Step 2: copy the net.sf.jadclipse_3.3.0.jar to the %ECLIPSE_HOME%/dropins directory.
Step 3:restart the eclipse ,then you will find the JadClipse menu existing in the main frame of Eclipse. In addition ,we navigate to Windows->preference->Java->JadClipse, if we find both of them ,it will stand for that we have installed the plug-in successfully.
Step 4: set the file association. Navigate to Windows->preference->General->Editor->File Association, you choose the File types with a extension name .class from the first window, and then choose “JadClipse Class File Viewer” from the second window, then click OK.