Eclipse can't open class declarations

Question

This is what happens when I try to open the declaration of Thread.class

I'm using Eclipse Standard/SDK

Version: Kepler Service Release 1 Build id: 20130919-0819

How could I fix this?

Thanks in advance!

Answer 1

Click the big button in the error and find the source code.

The JDK source is typically in Program Files\Java\jdk...\src.zip.