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Graphics2D ....

Hi Experts,

I tried to make a moving circle, but I got mistakes at line 00 & line 01 ? Does anyone know what I did wrong ? thanks.

//------------------------------------------
import java.lang.* ;
import javax.swing.*;
import javax.swing.event.* ;
import java.awt.* ;
import java.awt.event.* ;
import java.awt.image.BufferedImage;

public class MovingFigs extends JFrame{
private MovingItem movingCircle, movingRec ;
/** Creates a new instance of Main */
public MovingFigs() {

javax.swing.Timer circleTimer = new Timer(1000, movingCircle);
circleTimer.start();

setSize(400,400) ;
show();
}

class MovingItem implements ActionListener {

Graphics2D myCircle ;
int x = 30, y = 30;
final int DELTA_X =10;

myCircle.setColor(Color.red) ; // line 00
myCircle.fillOval(30,30,60,60) ; // line 01
public void actionPerformed(ActionEvent e) {
x += DELTA_X;
myCircle.fillOval(x, y, x+60, y);
}
}
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
}

}

CEHJ

If you want to paint on your frame, you'll have to override its paint method:

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

public class MovingFigs extends JFrame {
      private MovingItem movingCircle, movingRec;
      int x = 30, y = 30;
      final int DELTA_X = 10;

      public MovingFigs() {
            javax.swing.Timer circleTimer = new Timer(500, new MovingItem());
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            circleTimer.start();
            setSize(400, 400);
            show();
      }

      class MovingItem implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                  // Cause the ball to move
                  repaint();
            }
      }

      public void paint(Graphics g) {
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.clearRect(0, 0, getWidth(), getHeight());
            g2d.setPaint(Color.red);
            x += DELTA_X;
            g2d.fillOval(x, y, y, y);
            g2d.drawOval(x, y, y, y);
            g2d.dispose();
      }

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

}

meow00

ASKER

err ..... in the :
-------------------
class MovingItem implements ActionListener {
public void actionPerformed(ActionEvent e) {
// Cause the ball to move
repaint();
}
}
-------------------------
why does it call repaint() rather than paint ? thanks !

ASKER CERTIFIED SOLUTION

CEHJ

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CEHJ

8-)