Verified answer

I wrote a game called Canyon which uses the letter 'p' to pause the game.

Should give you some inspirationSee link.

Java Pause

You can either use KeyListener so the program will listen for that key being pressed and then pause it.

Or you can use KeyBinding.

I used Key Listener before and it was relatively straight forward.

I never used KeyBinding but it looks complicated enough.

As for actually pausing the game, I wouldn't be too sure. Some kind of thread perhaps?

Is it character mode or in graphic mode?

I mean is it simple Java Application or Java Applet?

If applet, do read about KeyListener related aspects