Below is snapshot of Java Decompiler program
You can download this program from here
I will illustrate how to use this program as External Tool in Jdeveloper
Integration between Java Decompiler and Jdeveloper
You can add this program to external programs in Jdeveloper and integrate it to open class files located in Jdeveloper
Follow below step:
1-open Tools menu > External Tools.. from Jdeveloper
2-Click New button to add new external program to Jdeveloper
3-Choose Tool type External Program and then click Next
4-Enter program path at your machine in program executable and enter ${file.path} in Arguments and click on next
5-You can write name that will be displayed in context menu later for example Java Decompiler and then click next
6-Check check boxes like the below image and then click next and then Finish
7- Now you can allocate any class file in application navigator and right click it and then choose Java Decompiler from context menu
8- It will open Java Decompiler program and it automatically open source code of UcmClient.class
Reference: Java Decompiler in Jdeveloper from our JCG partner Mahmoud A. ElSayed at the Dive in Oracle blog.
