当按下键盘按钮而不是循环播放时，如何执行一项操作

Question

    if(Keyboard.isKeyDown(Keyboard.KEY_I)) {
        if(ms != MenubarState.INVENTORY) ms = MenubarState.INVENTORY;
        else ms = MenubarState.CLOSED;
    }

This bit here is ran every render, so it obviously will be checking while the button is pressed. I want to be able to press it once, and only execute it once until I take my finger off and press it again.

How is this done? I am programming in java.

Answer 1

You could just remember if you executed the action:

boolean done = false;
if(Keyboard.isKeyDown(Keyboard.KEY_I)) {
    if(!done){
       if(ms != MenubarState.INVENTORY) ms = MenubarState.INVENTORY;
       else ms = MenubarState.CLOSED;
       done= true;
    }
}
else done= false;

Answer 2

I would recomend you take a look at these: http://docs.oracle.com/javase/tutorial/uiswing/events/keylistener.html https://en.wikipedia.org/wiki/Observer_pattern

You can create a class that implements the Keylisterner interface and extends the Observable class. You can have your class with your render loop in it implement the Observer interface. If you make your render class an observer to your keylistener class you can have the keylistener call a method containing:

if(ms != MenubarState.INVENTORY) ms = MenubarState.INVENTORY;
    else ms = MenubarState.CLOSED;

exactly once when the correct key is pressed.

Answer 3

LWJGL comes with a Keyboard.getEventKeyState(); If the key is being pressed, this will be true, false otherwise.

if(Keyboard.isKeyDown(Keyboard.KEY_I)) {
    if(Keyboard.getEventKeyState())
        ms = MenubarState.INVENTORY;
    else ms = MenubarState.CLOSED;
}

What this does is it checks to see if the key is being held down. If it is not, then the menu bar will be closed.