Trying to update a boolean from a class in another class D:

First of all, sorry for my english!

I have a problem, I´m trying to make a simple java videogame, and I make booleans for the inputs. The inputs works well, but when I try to update the booleans in another class, it doesnt work.

I put here the important classes

I put all the classes in this drive. Classes

package Launcher;

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

public class KeyHandler 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;
            System.out.println(upPressed);

        }
        if(code == KeyEvent.VK_S){
            downPressed = false;
        }
        if(code == KeyEvent.VK_A){
            leftPressed = true;
        }
        if(code == KeyEvent.VK_D){
            rightPressed = true;
        }

    }

    @Override
    public void keyReleased(KeyEvent e) {
        int code = e.getKeyCode();

        if(code == KeyEvent.VK_W){
            upPressed = false;

        }
        if(code == KeyEvent.VK_S){
            downPressed = false;
        }
        if(code == KeyEvent.VK_A){
            leftPressed = false;
        }
        if(code == KeyEvent.VK_D){
            rightPressed = false;
        }

    }
}

package Launcher;


import java.awt.*;
import java.awt.event.KeyListener;
import javax.swing.JPanel;


public class GamePanel extends JPanel  implements  Runnable{

    //Window settings variables
    KeyHandler KH = new KeyHandler();
    final int originalTileSize = 16; //16x16px
    final int scale = 3;
    final int tileSize = originalTileSize * scale; //48x48px
    final int maxScreenCol = 16; //Tiles in a column
    final int maxScreenRow = 12; //Tiles in a row
    final int maxScreenWidth = tileSize * maxScreenCol;
    final int maxScreenHeight = tileSize * maxScreenRow;


    Thread gameThread;


    //Player pos
    int playerX = 100;
    int playerY = 100;
    int playerSpeed = 4;
    public GamePanel(){



        //Window Settings with variable implementation
        this.setPreferredSize(new Dimension(maxScreenWidth, maxScreenHeight));
        this.setBackground(Color.black);
        this.setDoubleBuffered(true);
        this.addKeyListener(KH);
        this.setFocusable(true);


        }


    public void startGameThread(){
        gameThread = new Thread(this);
        gameThread.start();

    }

    public void update(){
        //System.out.println(playerY);
        boolean upP = KH.upPressed;
        //System.out.println(upP);
        if(upP){
            System.out.println("Updating");
            playerY -= playerSpeed;
        }
        else if(KH.downPressed == true){
            playerY += playerSpeed;
        }
        else if(KH.leftPressed == true){
            playerX -= playerSpeed;
        }
        else if(KH.rightPressed){
            playerX += playerSpeed;
        }

    }

    public void run(){
        while(gameThread != null){

            //System.out.println("Running game");

            //1.Update
            update();
            //2Draw screen info
            repaint();

        }




    }

I only want the update function get the boolean variables, for me to be able to move my character. Thank you so much!

Answer

I had a look at the other classes and the reason is outside the code above, it’s in class Launcher.Main:

public static void main(String[] args){
        
 WindowPanel WP = new WindowPanel();
 WP.windowPanel();
        
 GamePanel GP = new GamePanel();
 GP.startGameThread();
}

in here you create a new instance of class WindowPanel, which – by itself – create a another instance of GamePanel.

public void windowPanel(){

// ...

        GamePanel gamePanel = new GamePanel();
        window.add(gamePanel);

        window.pack();
// ...
}

So, the GamePanel that you created in Main, after you created the WindowPanel is not related to the GamePanel you create afterwards and start threading.

Fix:

remove the additional GamePanel from Main class
add to the end of windowPanel() method in WindowPanel class:

  gamePanel.startGameThread();

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Answer