If you profile your application, you can notice a graph like a saw tooth. Here is how you can determine this with the help of jconsole for the above bad key class example. All you have to do is while your MemoryLeak is running, get the Java process id by typing.
C:\>jps
5808 Jps
4568 MemoryLeak
3860 Main
Now, open up the jconsole as shown below on a command line
C:\>jconsole 4568