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How to use arrow keys instead of buttonListeners?

public void setUpButtonListeners() {
ActionListener buttonListener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
Object o = ae.getSource();
if ((o == slots[3][1]) || (o == slots[3][2])) {
slideDown(slots);
} else if ((o == slots[0][1]) || (o == slots[0][2])) {
slideUp(slots);
} else if ((o == slots[1][3]) || (o == slots[2][3])) {
slideRight(slots);
} else if ((o == slots[1][0]) || (o == slots[2][0])) {
slideLeft(slots);
}
}
};
slots[3][1].addActionListener(buttonListener);
slots[3][2].addActionListener(buttonListener);
slots[0][1].addActionListener(buttonListener);
slots[0][2].addActionListener(buttonListener);
slots[1][3].addActionListener(buttonListener);
slots[2][3].addActionListener(buttonListener);
slots[1][0].addActionListener(buttonListener);
slots[2][0].addActionListener(buttonListener);
}
This the relevant code. I can find a ton of information on how to add keylisteners to specific JComponents but all I want to do is make it so that if(up arrow pressed) then slideUp(slots), instead of having to press JButtons on the screen to call these functions.
Edit:
Fixed, and it was really simple.
Added
frame.setFocusable(true);
frame.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyPressed(KeyEvent e) {
keyCode = e.getKeyCode();
switch (keyCode) {
case KeyEvent.VK_UP:
slideUp(slots);
}
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
});
to constructor.

Maybe you should use a custom KeyEventDispatcher to handle the arrow key events, otherwise you will have issues with the components focus.
KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher( new ArrowsKeyDispatcher() );
...
class ArrowsKeyDispatcher implements KeyEventDispatcher {
public boolean dispatchKeyEvent(KeyEvent e) {
if(e.getID() == KeyEvent.VK_UP) {
//Do something here when pressing UP ARROWKEY
}
// Do the same for all keys you need to handle globally
...
return false;
}
}

unable to take keyboard inputs in java using KeyListener

i am trying to take keyboard inputs to change the boolean's value but keylisteners are not working
those bolleans values will be used later in other class
heres the method i am having issues with
public boolean upPressed, downPressed, leftPressed, rightPressed;
#Override
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if(code == KeyEvent.VK_W){
upPressed = true;}
else if(code == KeyEvent.VK_S){
downPressed = true;}
else if(code == KeyEvent.VK_A){
leftPressed = true;}
else if(code == KeyEvent.VK_D){
rightPressed = true;}
}
i am using a different class which extends JPanel, frame is in a different class and key listener is in a different class and i have this.setFocusable(true);this.addKeyListener(keyH);
and if u want, here's the full code : https://github.com/PROMAN8625/2dGAME

Your code snippet looks fine. Maybe you didn't add KeyListener to the frame.
Here is a working example:
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class KeyListenerExample implements KeyListener
{
public boolean upPressed, downPressed, leftPressed, rightPressed;
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e)
{
int code = e.getKeyCode();
if (code == KeyEvent.VK_W) {
upPressed = true;
}
else if(code == KeyEvent.VK_S){
downPressed = true;}
else if(code == KeyEvent.VK_A){
leftPressed = true;}
else if(code == KeyEvent.VK_D){
rightPressed = true;}
System.out.println("The key Pressed was: " + e.getKeyChar());
System.out.println("upPressed: " + upPressed);
System.out.println("downPressed: " + downPressed);
System.out.println("leftPressed: " + leftPressed);
System.out.println("rightPressed: " + rightPressed);
System.out.println("\n");
}
#Override
public void keyReleased(KeyEvent e) {
}
public static void main(String[] args)
{
//Setting the Frame and Labels
Frame f = new Frame("Demo");
f.setLayout(new FlowLayout());
f.setSize(500, 500);
Label l = new Label();
l.setText("This is a demonstration");
f.add(l);
f.setVisible(true);
//Creating and adding the key listener
KeyListenerExample k = new KeyListenerExample();
f.addKeyListener(k);
}
}

I'm having issues with CardLayout and one of the JPanels not receiving Keyboard events

I will only supply the relevant parts of the code as it is quite large. Help me figure out why I never get keyboard events to the GameBoard JPanel. The game code runs just fine until I added the new feature where I wanted it to have a welcome screen.
Edit: If you would like to view the entire project (it's an eclipse project), here is the link to download it Eclipse project, I honestly can't format almost 1000 lines of code here on StackOverflow, that'll be painful even for you.
Main.java
private void initUI() throws IOException {
cardLayout = new CardLayout();
mainPanel = new JPanel(cardLayout);
welcomeMenu = new Welcome(cardLayout, mainPanel);
mainPanel.add(welcomeMenu, "welcome");
game = new GameBoard();
mainPanel.add(game, "game");
add(mainPanel);
setTitle("Pacman");
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(380, 420);
setLocationRelativeTo(null);
}
This is the welcome/menu panel (some section of it).
Welcome.java (servers as a menu)
#Override
public void actionPerformed(ActionEvent evt) {
if (evt.getActionCommand() == Actions.EXIT.name()) {
System.exit(0);
} else if (evt.getActionCommand() == Actions.CONFIG.name()) {
JOptionPane.showMessageDialog(null, "Not yet implemented");
} else if (evt.getActionCommand() == Actions.PLAY.name()) {
// The part that switches to game, works as expected.
cl.show(mp, "game");
}
}
GameBoard class has a KeyAdapter class within it that is used to listen to key events, however, in the addition of the new feature using CardLayout, I could not get the key events to the panel so my PacMan is just stuck in one place opening and closing its mouth like a fish.
GameBoard.java
private void initBoard() {
addKeyListener(new TAdapter());
setFocusable(true);
setBackground(Color.black);
initGame();
}
...
class TAdapter extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (inGame) {
if (key == KeyEvent.VK_LEFT) {
req_dx = -1;
req_dy = 0;
} else if (key == KeyEvent.VK_RIGHT) {
req_dx = 1;
req_dy = 0;
} else if (key == KeyEvent.VK_UP) {
req_dx = 0;
req_dy = -1;
} else if (key == KeyEvent.VK_DOWN) {
req_dx = 0;
req_dy = 1;
} else if (key == KeyEvent.VK_ESCAPE && timer.isRunning()) {
inGame = false;
} else if (key == KeyEvent.VK_PAUSE) {
if (timer.isRunning()) {
timer.stop();
} else {
timer.start();
}
}
} /*
* else { if (key == 's' || key == 'S') { inGame = true; initGame(); } }
*/
}
#Override
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if (key == Event.LEFT || key == Event.RIGHT || key == Event.UP || key == Event.DOWN) {
req_dx = 0;
req_dy = 0;
}
}
}

The issue was using Key Listener when I should have been using Key Binding in the GameBoard JPanel. So instead of this,
class TAdapter extends KeyAdapter {
#Override
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if (inGame) {
...
} else if (key == KeyEvent.VK_UP) {
req_dx = 0;
req_dy = -1;
} else if (key == KeyEvent.VK_DOWN) {
...
}
}
}
I replaced it with this approach (I will only demonstrate Arrow Up scenario),
private class UpAction extends AbstractAction {
private static final long serialVersionUID = 1L;
#Override
public void actionPerformed(ActionEvent e) {
if (!inGame)
return;
req_dx = 0;
req_dy = -1;
}
}
...
private void setupKeyListeners() {
getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "doUp");
...
getActionMap().put("doUp", new UpAction());
...
}
And later on,
private void initBoard() {
setupListeners();
setFocusable(true);
setBackground(Color.black);
initGame();
}

KeyPressed/KeyReleased not working?

I'm trying to make a game in java, just a simple platformer, but I'm having difficulty when running the code. I can't seem to get any response from key presses. The only thing I can think hasn't been working properly is the keyPressed and keyReleased functions. Below is the relevant code.
public ReflexPanel() {
initBoard();
setFocusable(true);
addKeyListener(this);
Timer timer = new Timer(1000/120, this);
timer.start();
}
private void initBoard() {
loadMenu();
int w = menu.getWidth(this);
int h = menu.getHeight(this);
setPreferredSize(new Dimension(w, h));
}
private void step() {
if(mainMenu){
if(ePressed) {
System.exit(0);
}
if(hPressed) {
loadScores();
repaint();
}
}
}
public void keyTyped(KeyEvent e) {}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == 'e') {
ePressed = true;
}
if (e.getKeyCode() == 'h') {
hPressed = true;
}
}
#Override
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == 'e') {
ePressed = false;
}
if (e.getKeyCode() == 'h') {
hPressed = false;
}
}
#Override
public void actionPerformed(ActionEvent e) {
step();
}
The ePressed and hPressed variables are just booleans set to false by default, and loadScores calls a png file.

You can't do this:
if(e.getKeyCode() == 'e'){
// code logic
}
KeyEvent::getKeyCode doesn't return the char you press on the keyboard. It "returns the integer keyCode associated with the key in this event". When using KeyEvent::getKeyCode you have to use the KeyEvent key constants values predefined in the class. So for example:
if(e.getKeyCode() == KeyEvent.VK_E){
// code logic
}
Or you can use KeyEvent::getKeyChar which "returns the character associated with the key in this event".

You're using getKeyCode() which returns an int value with constants given in KeyEvent class, such as KeyEvent.VK_E.
You're looking to use getKeyChar() which returns 'e' directly.
if (e.getKeyChar() == 'e') { // Now it has an actual chance of working

KeyListener in another class, problems adding it to the JFrame

first class
private void spielfenster() {
setSize(1280, 720);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("");
setLayout(null);
setLocationRelativeTo(null);
addKeyListener(new Steuerung());
}
[...]
private void run() {
while(true){
if(we.nachRechts == true && we.mariox < (1280 - 38)){
we.mariox += 4;
repaint();
}
if(we.nachLinks == true && we.mariox > 0){
we.mariox -= 4;
repaint();
}
try {Thread.sleep(10);} catch (InterruptedException e) {e.printStackTrace();}
}
}
2nd class
package game;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
public class Steuerung extends KeyAdapter{
public Werte we = new Werte(); //object, to get access to the global values in class "Werte"
public void keyPressed(KeyEvent p){
int keys = p.getKeyCode();
if(keys == KeyEvent.VK_D){we.nachRechts = true;}
if(keys == KeyEvent.VK_S ){we.nachLinks = true;}
}
public void keyReleased(KeyEvent r){
int key = r.getKeyCode();
if(key == KeyEvent.VK_D){we.nachRechts = true;}
if(key == KeyEvent.VK_S ){we.nachLinks = true;}
}
}
New Problem: when i put this exact code of the key-listener in the class "Spielfenster" its working fine. Where is the problem?
2nd problem (bot not really important for me right now, but also good to know): if im creating an "Spielfenster" object in class "Steuerung" the frame opens himself about 10 times per sec. ?!
Thanks in previous! Palm