How to see the source code for java SDK (java.lang, java.util, …) classes in Eclipse?

Question

I want to read jar class files into my eclipse. Suppose I wrote the following code:

List list = new ArrayList();

When I ctrl click on List, it

Answer 1

you have to add Eclipse Plugin from

HELP -> Eclipse Marketplace

I personally used

Enhanced Class Decompiler

just install it. and have fun.