Eclipse type hierarchy not always working

Question

When I want to see implementation of some interface through F4 (type hierarchy) or ctrl+t (quick hierarchy) or implementation of a method, I

Answer 1

I also had this problem and fixed it. The reason of this problem is that when the eclipse is running, I reinstall the JDK from 1.8 to 1.6. So I close eclipse, install JDK 1.8 again, then it's OK! May it will be helpful for others.