Java GUI: How to make an object move using arrow keys?

Question

I am new to java programming and I am trying to move the object using the arrow keys using KeyListener but the object does not move. I've googled it but I can't seem to figure out where I'm going wrong. I was able to move the object on it's own but nothing happens after I set the velocity to 0 and added the keyListener. Please check my code and help me figure out what I did wrong.

import java.awt.*;
import javax.swing.*;
import java.io.*;



   public class Games extends JFrame{
    public Games(){
    super.setTitle("Sokoban");
    super.setSize(600, 600);
    super.setLocation(400, 300);
    super.setResizable(false);

    super.add(new Contents());
    super.setVisible(true);
    super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    super.setLayout(new BorderLayout());




}


public static void main(String[] args)  {
    new Games();





}


    }import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.Timer;

public class Contents extends JPanel implements ActionListener, KeyListener {
    private Image person;
    private int x=0, y= 0;
    private int speedXCordinate= 0, speedYCordinate= 0;

Timer time  = new Timer(7, this);



public Contents(){
    super.setDoubleBuffered(true);

    time.start();
    addKeyListener(this);
    setFocusable(true);
    setFocusTraversalKeysEnabled(false);



}

@Override
public void paintComponent(Graphics g){
    ImageIcon p = new ImageIcon(this.getClass().getResource("person.jpeg"));
    Graphics2D q = (Graphics2D) g;


    person = p.getImage();
    q.drawImage(person, x, y, this);






}



@Override
public void actionPerformed(ActionEvent e) {

   repaint();
   x+= speedXCordinate;
   y+=speedYCordinate;




}

public void up(){
    speedXCordinate=0;
    speedYCordinate=-1;
}
public void down(){
    speedXCordinate=0;
    speedYCordinate=1;
}
public void left(){
    speedXCordinate=-1;
    speedYCordinate=0;
}
public void right(){
    speedYCordinate=1;
    speedYCordinate=0;
}

@Override
public void keyTyped(KeyEvent e) { . //method for moving object
    int c= e.getKeyCode();
    if( c == KeyEvent.VK_LEFT){
       left();
    }
    if(c==KeyEvent.VK_RIGHT){
        right();
    }
    if(c==KeyEvent.VK_UP){
        up();

    }
    if(c==KeyEvent.VK_DOWN){
       down();


    }


}

@Override
public void keyPressed(KeyEvent e) {

}

@Override
public void keyReleased(KeyEvent e) {
    speedXCordinate=0;
    speedYCordinate=0;

}

}

There are a couple of simple things you can do to get this code working better. Firstly, in your `paintComponent(Graphics g)` method include a call to `super.paintComponent(g)` before drawing your image. This will cause the background to be repainted and avoid unwanted painting artifacts. Next, move all the code in your `keyTyped(KeyEvent e)` method into your `keyPressed` method instead. You cannot use `e.getKeyCode()` inside the `keyTyped` method as it always returns `VK_UNKNOWN` there. Finally there is a little bug in your `right()` method. Hope this helps! — Julian Wright, Jun 26 '19 at 04:35

score -2 · Answer 1 · answered Jun 24 '19 at 21:42

-2

It looks like you need a delay in between setting your X and Y speeds, this can be done using Thread.sleep(milliseconds) in between setting the speed and changing it back to 0.

answered Jun 24 '19 at 21:42

finman

40
6

1

Using `Thread.sleep(...)` will block the EDT, OP is correctly using a Swing Timer, but needs to use KeyBindings. – Frakcool Jun 24 '19 at 21:45
Sorry, but this recommendation will just lead the original poster to more pain. Please retract it. – Hovercraft Full Of Eels Jun 24 '19 at 22:29

Java GUI: How to make an object move using arrow keys?

1 Answers1