how to double buffer in multiple classes with java

Question

I am creating a Java 2D video game. I can load graphics just fine, but when it gets into double buffering I have issues. If i run this code, nothing is displayed except for the string("hello"); but the image is not displayed. now if i modified the code and exluded the Buffered Image the image would show just fine, so my question is how do i use a buffered image to draw sprites and also how do i do this a cross different classes?

My source code

package myPackage;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;

public class GameView extends JFrame {

    private BufferedImage backbuffer;
    private Graphics2D g2d;

    public GameView() {

        setBounds(0, 0, 500, 500);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        backbuffer = new BufferedImage(getHeight(), getWidth(),
                BufferedImage.TYPE_INT_BGR);
        g2d = backbuffer.createGraphics();

        Toolkit tk = Toolkit.getDefaultToolkit();
        Image img = tk.getImage(this.getClass().getResource("cage.png"));
        g2d.setColor(Color.red);
        //g2d.drawString("Hello",100,100);
        g2d.drawImage(img, 100, 100, this);
        repaint();
    }

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

    public void paint(Graphics g) {
        g2d = (Graphics2D)g;
        g2d.drawImage(backbuffer, 0, 0, this);
    }

}

Answer 1

I am not sure why but the problem was solved when i implemented runnable and drew to the g2d object within the run method.

Solved Source Code:

package myPackage;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;

public class GameView extends JFrame implements Runnable {

    public BufferedImage backbuffer;
    public Graphics2D g2d;
    public Image img;
    Thread gameloop;

    public GameView() {
        super("Game View");
        setSize(600, 600);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        backbuffer = new BufferedImage(600, 600, BufferedImage.TYPE_INT_RGB);
        g2d = backbuffer.createGraphics();

        Toolkit tk = Toolkit.getDefaultToolkit();
        img = tk.getImage(this.getClass().getResource("cage.png"));
        gameloop = new Thread(this);
        gameloop.start();

    }

    public static void main(String args[]) {

        new GameView();
    }

    public void paint(Graphics g) {

        g.drawImage(backbuffer, 0, 0, this);

    }

    @Override
    public void run() {
        // TODO Auto-generated method stub
        Thread t = Thread.currentThread();
        while (t == gameloop) {
            g2d.drawImage(img, 100, 100, this);
        }
    }

}

Answer 2

Look at your code, my guess is that your image is not displayed. I think you should be extending JPanel instead of JFrame. Add that panel into the frame. You will also need to override the preferred