Oracle SQL developer (4.2) has an issue with Java version.
If you specify some incompatible version when you first time start the app, it keeps complaining every time you start it with following error:
The suggested config change in the message is red-herring. It doesn’t actually fix the problem. Apparently we need to modify configuration file %AppData%\sqldeveloper\product.conf to fix the problem.
The file %AppData%\sqldeveloper\product.conf contains entry for SetJavaHome. Comment the existing entry and add an entry for a valid java version.
#SetJavaHome C:\Program Files\Java\jdk1.6.0_37
While this is a solution for the java version issue, your SQL Developer may still crash!
Best and quickest way to solve it is to delete 'SQL Developer' and 'sqldeveloper' folders in %AppData% folder and start sql developer a fresh.