Reopen Java window after hiding it on close

I'm building an application, and the biggest problem that I'm having that needs to be attended to asap is the reopening of the application. I'm not sure how to word this so sorry if it sounds weird.

I can launch my application just fine. It creates the main window. I'm also using the setDefaultCloseOperation(HIDE_ON_CLOSE) I have also tried DISPOSE_ON_CLOSE but they both have the same effect. So when I close it the window closes out. However, when I click on the icon in my dock the window won't open back up. Any advice is greatly appreciated thanks.