unable to take keyboard inputs in java using KeyListener

Question

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

The keyPressed method does not look bad. How are you using it? What is the surrounding code? — queeg
– queeg, Commented Feb 7, 2022 at 11:55
I think you should include an minimal reproducible example. Note the "minimal" - not your whole program, just a stripped down version. — RealSkeptic
– RealSkeptic, Commented Feb 7, 2022 at 12:04

Sabina Plestenjak · Accepted Answer · 2022-02-07 15:32:42Z

1

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);
    }
}

edited Feb 7, 2022 at 15:32

answered Feb 7, 2022 at 12:10

Sabina Plestenjak

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5 Comments

Community Over a year ago

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

PROMAN8625 Over a year ago

I have added keylistener to the panel

Sabina Plestenjak Over a year ago

The frame needs to be in focus when you press keys. I edited my answer with a complete example.

PROMAN8625 Over a year ago

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);

PROMAN8625 Over a year ago

the code worked!

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