facing the issue while debugging

“String.hashCode() line: not available”
i have refereed this , How to debug .class files in ECLIPSE? but this talks of debug build, but i want to know what is wrong with my existing system
@ siegi I have done these changes and not able to modify the highlighted(blue) par to point to C:\Program Files\Java\jdk1.6.0_31\jre\lib\rt.jar

one more problem:
String.hashCode() line: 1489 [local variables unavailable]

I think the problem is you are using the class files from the JRE. I guess they are compiled without the
LineNumberTableattribute. You can try to run your application with JDKs JRE (if I remember correctly on Windows the path should be something likeC:\Program Files\Java\jdk6\jre).