Keyboard input wont work

Newbie & Debugging Questions
#1

hi guys,
i’ve been learning with the JavaHug beginner game development and i can’t find why the keyListener doesn’t work, here is the code,
thank you


package javagame;

import java.awt.Graphics;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;

public class JavaGame extends JFrame{
	
	int x,y;
	
	public class AL extends KeyAdapter{
		public void KeyPressed(KeyEvent e){
			int keyCode = e.getKeyCode();
			if(keyCode == e.VK_LEFT){
				x--;
				
			}
			if(keyCode == e.VK_RIGHT){
				x++;
				
			}
			if(keyCode == e.VK_UP){
				y--;
				
			}
			if(keyCode == e.VK_DOWN){
				y++;
				
			}
		}
		
		public void KeyReleased(KeyEvent e){
			
		}
	}
	
	
	
	public JavaGame(){
		addKeyListener(new AL());
		setTitle("JavaGame");
		setSize(300,250);
		setResizable(false);
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		x = 150;
		y = 150;
		
		
	}
	
	
	
	
	public void paint(Graphics g){
		
		g.fillOval(x, y, 15, 15);
		
		repaint();
	}
	
	
	public static void main (String[] arghs){
		new JavaGame();
	}
	
}
#2

I’m not exactly sure what KeyAdapter is or what you’re doing with it but here is what a working KeyListener looks like (CnPd from my game):

package Functions;

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

public class KeyboardListener implements KeyListener
{
    int xpos = 0; //Player's X and Y positions on the current map.
    int ypos = 0;
    
    public KeyboardListener()
    {
    }

    public void keyPressed(KeyEvent event)
    {
        int keyCode = event.getKeyCode();

        if (keyCode == 87) //w key pressed
        {
            ypos++;
        }
        else if (keyCode == 65) //a key pressed
        {
            xpos--;
        }
        else if (keyCode == 83) //s key pressed
        {
            ypos--;
        }
        else if (keyCode == 68) //d key pressed
        {
            xpos++;
        }
        else if (keyCode == 38) //up arrow key pressed
        {
            ypos++;
        }
        else if (keyCode == 37) //left arrow key pressed
        {
            xpos--;
        }
        else if (keyCode == 40) //down arrow key pressed
        {
            ypos--;
        }
        else if (keyCode == 39) //right arrow key pressed
        {
            xpos++;
        }
    }

     public void keyReleased(KeyEvent event)
     {
        int keyCode = event.getKeyCode();

        if (keyCode == 87) //w key released
        {
        }
        else if (keyCode == 65) //a key released
        {
        }
        else if (keyCode == 83) //s key released
        {
        }
        else if (keyCode == 68) //d key released
        {
        }
        else if (keyCode == 38) //up arrow key released
        {
        }
        else if (keyCode == 37) //left arrow key released
        {
        }
        else if (keyCode == 40) //down arrow key released
        {
        }
        else if (keyCode == 39) //right arrow key released
        {
        }
    }

    public void keyTyped(KeyEvent event) //This needs to be here or else an abstract error will be shown when compiling, don't worry; Just keep this here.
    {
    }
    
    //Get methods
    public int getXpos()
    {
        return xpos;
    }
    
    public int getYpos()
    {
        return ypos;
    }
}

Disregard some of the comments, they’re for me and not you.

#3

:o
…

Please, don’t use those numbers and comments. Those awesome constants (/finals) were invented:

KeyCode.VK_UP; // "Up" keycode
#4

Are you using an IDE? KeyPressed and KeyReleased are not valid KeyAdapter methods, the k should be lowercase. Also, do you absolutely have to have a separate class for event handling? Seems easier to just have the main class implement KeyListener, seeing as you’re not doing too much custom stuff in class AL.
That repaint() call in the paintComponent() method looks suspicious, I realize this isn’t the full source but you should be using a proper game loop. And yeah, like matheus said, use the statics :slight_smile:

#5

Also if you’re going to use more than 3 if statements, you should use a switch:

switch( keyCode )
{
	case KeyCode.VK_UP:
		ypos++;
		break;
	case KeyCode.VK_DOWN:
		ypos--;
		break;
}

For multiple keys doing the same thing:

switch( keyCode )
{
	case KeyCode.VK_W:
	case KeyCode.VK_UP:
		ypos++;
		break;
	case KeyCode.VK_S:
	case KeyCode.VK_DOWN:
		ypos--;
		break;
}

Good night. ;D

#6

thanx everyone, problem solved, it was caused by the upper case “K” it should be “keyPressed” not “KeyPressed”

#7

If you use eclipse:
write @Override in front of your methods like that:


@Override
public void keyPressed(...) { ... }

Then eclipse will tell you, if you misspelled the method name, or have put the wrong method arguments.