I\'ve been using Eclipse for some time already, and I didn\'t have any problems with it. However, when I tried to generate some javadoc, I found that I didn\'t have the SDK
There is no need for reinstalling eclipse IDE or changing your environment variables. I had encountered this problem while working on my project I had this issue but I fixed it in no time and it works fine for me.
Before implementing any solution, Check first that you don't have multiple installations of JDK in your system. I have encountered many systems with JDK 1.7 and JDK 1.8. If it is so, simply change your -vm to the alternate jdk C:\Program Files\Java\jdk1.7.0_60(jdk version you were not using)\jre\bin\client\jvm.dll and start your eclipse IDE. IT will work but the workspace will not synchronized and the files will not be getting displayed. Just close your IDE and revert to your previous jdk link and Voila It works.
In case you have a single JDK installed in your system. I suggest clearing your CPU Physical memory. It so happens JVM has issues in execution if a lot of memory is utilised. Just go to the Task manager and close any redundant processes.
Hope this helps! Keep Coding :)