I am creating a simple game in which a keypressed event moves a JLabel a certain number of pixels in a JPanel.
It works without any errors and when i hit the right arrow it moves right, and so on. However, as soon as i press a second key it interrupts the original movement.
For example if i was holding down the left key (and the object was moving left) and then i hit the up arrow the object stops moving left. This is (of course) because i am using only one key event for all my key.
This obviously is not an acceptable situation because as soon as i add a second object (for another player) each player will be constantly stopping the other players movement.
So my question is this: How best can i incorporate multiple simultaneous key actions? (preferably without writing dozens of KeyAdapter's and KeyEvent's)
INFO: currently i have a second class which extends a KeyAdapter. This second class includes a KeyPressed function which then uses .getKeyCode(); to find out which key is pressed and act.
EDIT: any suggestions are welcome!
The solution is actually quite simple. When a key pressed event is registered store a variable that records the movement. When a key released event is registered un-store that variable.
This then means that until you release you keys the movement will continue to be registered. The solution also requires a timer in order to loop repeatedly and check if your event is running or not. You could use a delay but a separate thread is the most effective for this type of task.
First you need a global variable that can store your action:
String action = "";
Then you need a key listener to record your input and when you stop inputting:
// create key listener
addKeyListener(new KeyListener()
{
@Override
public void keyPressed(KeyEvent e)
{
int keyCode = e.getKeyCode();
String event = KeyEvent.getKeyText(keyCode);
if (event.equals("A")) {
// DO YOUR EVENT IF THE KEY HAS BEEN PRESSED
action = "A";
}
}
@Override
public void keyTyped(KeyEvent e) {}
@Override
public void keyReleased(KeyEvent e) {
int keyCode = e.getKeyCode();
String event = KeyEvent.getKeyText(keyCode);
if (event.equals("A")) {
// STOP DOING YOUR EVENT
action = "";
}
}
});
Lastly you will need a timer thread to loop and do your action:
// CREATE A TIMER THREAD
Timer timer = new Timer();
timer.schedule(new TimerTask() {
// this is what happens every time the timer runs
@Override
public void run() {
// check if your action should be preformed
if (action.equals("A")) {
// ... do something
}
}
}, 0, 1000); // 1000 MILLESECONDS = 1 SECOND
// note: you will need to run 'timer.cancel();' at some point to end your timer
Also it is worth looking at these other topics, including this about keylistener is games. And about timer tasks.