handle multiple key presses ignoring repeated key

Question

I had asked this in the comments section of another question (> How do I handle simultaneous key presses in Java?), and was asked to make a new question altogether.

Answer 1

Looks like you are not handling threading in Java right. There are three threads (minimum) to any Java program. They are the main program thread, the event dispatch thread, and one more that i can't remember right now.

Whenever you get an event it is delivered to you by a special thread (I believe it's the event dispatch thread, but that is besides the point). You are not allowed to do anything (that takes time) on this thread, that will freeze up your input and cause you to miss events, making Java look unresponsive. So what has happened is you have broke the event system in java. What you should do is store the result in some sort of buffer, which is the fasted thing you can be expected to do with the event, then it is handled later as I will describe.

[Aside: A funny application is to make a simple gui, and on the press of the button call wait on the thread for like 5 seconds. Your entire gui will freeze until the delay has finished!]

You should have a different thread running on the side (probably your main thread). It will run some sort of loop, which controls the frames in your program, completing once per game cycle. Once each cycle this thread reads the results stored in the input buffer and processes them. The theory behind this is simple, but the execution can be a little messy, because you will need to make sure that no input events are dropped or read more then once. Either way, good luck with your game!