How do Java applications close on Mac OS X?

I am writing a Java program to run on Mac OS X. However, one thing that has confused me is that I have seen some people say that if the user leaves the application from the menu bar, the application does not close properly - it will not cleaned up correctly and I have to implement a separate closure method for it. However, I also read that there were some big changes for Java for Mac in 2010. When I look at the Apple Docs , it seems that the default close action now calls SYSTEM_EXIT_0. Does this mean it is calling System.exit (0)? Is this a solution to the cleaning problem? I am a little confused about all the API changes and all the omissions that happened when Apple stopped controlling Java for Mac.

Thank!