Target JRE in Eclipse

Question

How should I change Target JRE in Eclipse. I was earlier using jdk1.7, now I want to use JDK 1.6. But while running my java program I am getting Unsupported Class Version Er

Answer 1

Go to

Window -> Preferences ->

Now Select and Expand Java

Now Select option Installed JREs

and now you can add new JRE to it.