I want to addKeyListener to a JPanel but when I press two keys at the same time, just one of them executes. What is the solution to this problem - press two keys at the same time?
I have a class that extends JPanel
this.addKeyListener(new KeyListener() {
public void keyTyped(KeyEvent e) {}
public void keyReleased(KeyEvent e) {}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_W) {
upPlayer2();
} if (e.getKeyCode() == KeyEvent.VK_A ){
leftPlayer2();
}
}
});
Thanks.
Don't use a KeyListener. Swing was designed to be used with Key Bindings.
See Motion Using the Keyboard for more information and solutions.
Related
We areto create a plane and have its speed increase 5mph every time the user inputs the up arrow key and decrease 9mph when hitting the down key. It is supposed it report this back to the user in output box whenever whichever action is completed. How do I set it up so that the keylistener will tell the user that they have pressed the up key? Im still working on this so sorry if it is messy.
private class PolygonPanel implements MouseListener, MouseMotionListener, KeyListener
{
public void mousePressed(MouseEvent event){} //unused event
public void mouseDragged(MouseEvent event){} //unused event
public void keyReleased(KeyEvent event){}
public void keyTyped(KeyEvent event){}
//public void keyPressed(KeyEvent event){}
public void keyPressed(KeyEvent event) {
Integer planespeed=event.getKeyCode();
if (event.getKeyCode() == KeyEvent.VK_RIGHT)
{
//Not gonna use this.
}
if (event.getKeyCode() == 39)//KeyEvent.VK_LEFT
{
System.out.print("This key is up");
}
if (event.getKeyCode() == KeyEvent.VK_UP)
{
System.out.print("This key has been pressed");
//speed=planespeed+5;
}
if (event.getKeyCode() == KeyEvent.VK_DOWN)
{
//speed=planespeed-9;
}
repaint();
}
A frame doesn't detect keybaord input if it is not focused on. Therefore, in order to retrieve keyboard input of any kind, you would have to set your frame to be focusable, using a line such as setFocusable(true); in your constructor. You might also have to add a line such as addKeyListener(new PolygonPanel()); so the listener is registered at all.
So I am basically creating a platformer game in java. Here is a simple question. Can I respond to two different KeyEvents simultaneously? For example, I am pressing the right arrow key and my player is moving right. Now, I want my player to jump but keep moving right. For this I would need to respond to two different KeyEvents simultaneously. How do I achieve this? I have not tried any code yet because I don't know where to start with. Thank you for the answer in advance.
You can use seperate "KeyDown" and "KeyUp"-events and set state values for your player.
You need a State-Machine for your player.
public class KeyboardListener extends JFrame implements KeyListener {
public KeyboardListener() {
addKeyListener(this);
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right key pressed");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left key pressed");
}
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("Right key Released");
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("Left key Released");
}
}
public static void main(String[] args) {
new KeyboardListener();
}
}
Use the keyPressed and keyReleased-EventHandlers from the KeyListener Interface and save your current player states like walking, jumping, walk_left, walk_right etc as booleans for example.
In your mainloop you can check what state your player is in and change its coordinates. Like:
if(player.left) { player.x += speed } //etc.
You might want to use Threads and then add pressed keys to a list the player physics class.
public class KeysListener implements KeyListener
...
//FIRST THREAD
new Thread(new Runnable() {
#Override
public void run() {
public void keyEvent(KeyEvent e) {
int key = e.getKeyCode();
//TODO ADD KEY TO A LIST IN THE CLASS THAT HANDLES YOUR PHYSYICS
}
}
}).start();
//SECOND THREAD
new Thread(new Runnable() {
#Override
public void run() {
public void keyEvent(KeyEvent e) {
int key = e.getKeyCode();
//TODO ADD KEY TO A LIST IN THE CLASS THAT HANDLES YOUR PHYSICS
}
}
}).start();
...
}
Add as many threads as the number of simultaneous keys you require.
I have a Graphics project that contains KeyListener, where the arrow keys and space bar controls the movement of a spaceship. However, when a key is held down, it registers the next key presses after a delay after the first. I would like for a held down key to register continuously.
I suspect that this is due to my computer's setting for key repeat delay, so is there any way to temporarily override this in my program, or a workaround for it?
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == 38) { //Up Arrow
currentLevel.moveSpiffUp();
} else if (e.getKeyCode() == 40) { //Down Arrow
currentLevel.moveSpiffDown();
} else if (e.getKeyCode() == 32 && !currentLevel.getFrapRayActive()) {
currentLevel.shoot();
}
repaint();
}
I would suggest using key press and key released
public class MyKeyListener implements KeyListener {
//class gets the input from the player
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
if(KeyEvent.getKeyText(e.getKeyCode()).equals("Left")) {
//left arrow key
} else if (KeyEvent.getKeyText(e.getKeyCode()).equals("Right")) {
//right arrow key
}
}
public void keyReleased(KeyEvent e) {
if(KeyEvent.getKeyText(e.getKeyCode()).equals("Left"){
//left key released
}
if(KeyEvent.getKeyText(e.getKeyCode()).equals("Right")) {
//right key released
}
}
}
I then used this bit of code in my main constructor
main() {
KeyListener listener = new MyKeyListener();
addKeyListener(listener);
setFocusable(true);
}
This way you wont have your delay when hitting keys.
So everything in my program works, except for the mouse and the keyboard listeners.
I've got a couple actionListeners working on Jbuttons that do exactly what I'm trying to do here, but the assignment says it has to work with all three.
So I would like to know why it compiles, but doesn't work. Am I doing something wrong?
panel.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_UP){
shape.addSides();
}
if(e.getKeyCode() == KeyEvent.VK_DOWN){
shape.subSides();
}
}
#Override
public void keyReleased(KeyEvent e) {
}
}
);
panel.addMouseListener(new MouseListener(){
#Override
public void mouseEntered(MouseEvent e){
if(e.getButton() == MouseEvent.BUTTON1){
shape.addSides();
}
if(e.getButton() == MouseEvent.BUTTON3){
shape.subSides();
}
}
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
}
);
Regarding KeyListener: it won't work unless the listened-to component is focusable and has focus. So you will want to call setFocusable(true) and requestFocusInWindow() on your JPanel. As for the MouseListener -- something else may be taking the mouse event and preventing it from reaching your JPanel. To debug this you need to post a minimal, compilable, runnable example program.
Also regarding your MouseListener, you're checking getButton() in a mouseEntered event which makes no sense. The buttons are not involved in this type of event. Are you instead meaning to check mouseDragged(...) of a MouseMotionListener?
Is it possible to clear a listener that I put on my JPanel? When I call a method, I put a KeyListener on the panel but when I quit this method, I want to clear that listener.
Here is my method :
private void stopBall(final Graphics2D g2, int posBallY, String winner) {
move = false;
scorePanel.showPressSpace(true);
setFocusable(true);
requestFocus();
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e){
if (e.getKeyCode() == KeyEvent.VK_SPACE){
setPosX(getPlayPanelWidth()/2);
setPosY(0);
move = true;
scorePanel.showPressSpace(false);
initBall(g2);
}
}});
if (winner == "player1") {
scoreCountPlayer1++;
scorePanel.getLab_Player1().setText("" + scoreCountPlayer1);
} else if (winner == "comp") {
scoreCountComputer++;
scorePanel.getLab_Computer().setText("" + scoreCountComputer);
}
}
You have an unqualified call to addKeyListener(KeyListener), so I presume that you've extended JPanel. If so, then you can call removeKeyListener(KeyListener). In your current code, your key listener is anonymous. You'll need to change it just a bit to hold on to that reference, like so:
// Create a variable holding the listener
KeyAdapter keyAdapter = new KeyAdapter()
{
public void keyPressed(KeyEvent e)
{
if (e.getKeyCode() == KeyEvent.VK_SPACE)
{
setPosX(getPlayPanelWidth() / 2);
setPosY(0);
move = true;
scorePanel.showPressSpace(false);
initBall(g2);
}
}
};
// Register the listener with this JPanel
addKeyListener(keyAdapter);
// Time passes...
// Remove the listener from this JPanel
removeKeyListener(keyAdapter);
Or the way with the absolute minimal adjustments to your code
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e){
if (e.getKeyCode() == KeyEvent.VK_SPACE){
((JPanel)e.getSource()).removeKeyListener( this );
setPosX(getPlayPanelWidth()/2);
setPosY(0);
move = true;
scorePanel.showPressSpace(false);
initBall(g2);
}
}
});
But as already stated in the comments, you should opt for keybindings instead of keylisteners