Java intersects method not working Properly

Question

Could someone please tell me why my code does not work Properly?

I am trying to make the colour change when I move over it but its just not working.

I'm using the intersects method.

package com.dilkiel.game;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;

import javax.swing.ImageIcon;
import javax.swing.JPanel;

public class Screen extends JPanel implements Runnable {

private static final long serialVersionUID = 1L;

private Thread thread;

public int tickCount = 0;
public boolean running = false;
public int xPlayerOffset = 100;
public int yPlayerOffset = 100;
public int WIDTH = 1280;
public int HEIGHT = 720;

public InputHandler input = new InputHandler(this);

public Screen() {
    setFocusable(true);
    setMaximumSize(new Dimension(WIDTH, HEIGHT));
    setMinimumSize(new Dimension(WIDTH, HEIGHT));
    setPreferredSize(new Dimension(WIDTH, HEIGHT));
    start();
}

public void tick() {
    tickCount++;
    if (input.up.isPressed()) {
        yPlayerOffset -= 5;
    }
    if (input.down.isPressed()) {
        yPlayerOffset += 5;
    }
    if (input.left.isPressed()) {
        xPlayerOffset -= 5;
    }
    if (input.right.isPressed()) {
        xPlayerOffset += 5;
    }
}

public synchronized void start() {
    running = true;
    thread = new Thread(this, "Game Loop");
    thread.start();
}

public synchronized void stop() {
    running = false;
    try {
        thread.join();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

Image frontView = new ImageIcon("res/frontView.png").getImage();
Rectangle player = new Rectangle(xPlayerOffset, yPlayerOffset + 40, 40, 40);
Rectangle box = new Rectangle(250, 250, 80, 80);

public void paint(Graphics g) {

    g.setColor(Color.CYAN);
    g.fillRect(0, 0, WIDTH, HEIGHT);
    g.drawImage(frontView, xPlayerOffset, yPlayerOffset, this);

    g.setColor(Color.BLACK);
    if (player.intersects(box)) {
        //i want this to work can you please show me how. Thanks
        g.setColor(Color.GREEN);
    }
    g.fillRect(xPlayerOffset, yPlayerOffset + 40, 40, 40);
    g.fillRect(250, 250, 80, 80);
    g.dispose();
}

public void run() {
    long lastTime = System.nanoTime();
    double nsPerTick = 1000000000D / 60D;

    int ticks = 0;
    int frames = 0;

    long lastTimer = System.currentTimeMillis();
    double delta = 0;

    while (running) {
        long now = System.nanoTime();
        delta += (now - lastTime) / nsPerTick;
        lastTime = now;
        boolean shouldRender = false;

        while (delta >= 1) {
            ticks++;
            tick();
            delta -= 1;
            shouldRender = true;
        }
        /*
         * try { Thread.sleep(2); } catch (InterruptedException e) {
         * e.printStackTrace(); }
         */
        if (shouldRender) {
            frames++;
            repaint();
        }

        if (System.currentTimeMillis() - lastTimer >= 1000) {
            lastTimer += 1000;

            System.out.println(ticks + ", " + frames);
            frames = 0;
            ticks = 0;
        }
    }
}
}

Answer 1

I addressed some points that might help you.

1. Use Swing Timer instead of Thread

   Learn more How to Use Swing Timers

2. Override paintComponent() method for custom painting instead of overriding paint() method.

3. Don't forget to call super.paintComponent() in overridden method.

4. Override JComponent#getPreferredSize() instead of using setPreferredSize()

   Learn more Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?

---

Sample code: (Custom painting in JPanel)

final JPanel panel = new JPanel(){
    @Override
    public void paintComponent(Graphics g){
        super.paintComponent(g);
        // your custom painting code here
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(..., ...);
    }
};

Sample code: (Swing Timer)

// wait for 1 second
Timer timer = new Timer(1000, new ActionListener() {
    
    @Override
    public void actionPerformed(ActionEvent arg0) {            
        // next call 
    }
});
timer.setRepeats(false);
timer.start()

Answer 2

I think instead of using intersect method , you can add an on Mouse hover listener and write the code to change the colour within it which is better as it gives you more control and response.