Answer to Question #6690 in Java | JSP | JSF for Joe

Question

Building a GRect program in java, it creates rectangle and then allows user to enter a new height of the rectangle. When the program runs the rectangle starts at the bottom left of the screen which it should but when user enters new height the program flips the rectangle to the top of screen and the rectangle grows down the screen, any help?

Answer 1

package grect;
import java.awt.Container;
import
java.awt.Dimension;
import java.awt.Graphics;
import
java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import
java.awt.event.WindowAdapter;
import
java.awt.event.WindowEvent;

import javax.swing.JButton;
import
javax.swing.JFrame;
import javax.swing.JPanel;

public class Main
{
public static void main(String[] args) {
JFrame frame = new
BounceThreadFrame();
frame.show();
}
}
final class BounceThreadFrame
extends JFrame {

public BounceThreadFrame() {
setSize(300,
200);
setTitle("Bounce");
addWindowListener(new WindowAdapter()
{
@Override
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
});
Container contentPane =
getContentPane();
canvas = new JPanel();
contentPane.add(canvas,
"Center");
JPanel p = new JPanel();
addButton(p, "Start", new
ActionListener() {
public void actionPerformed(ActionEvent evt) {
Rect b =
new Rect(canvas);
b.start();
}
});
addButton(p, "Close", new
ActionListener() {
public void actionPerformed(ActionEvent evt)
{
canvas.setVisible(false);
System.exit(0);
}
});
contentPane.add(p,
"South");
}
public void addButton(Container c, String title,
ActionListener a) {
JButton b = new
JButton(title);
c.add(b);
b.addActionListener(a);
}
private JPanel
canvas;
}
class Rect extends Thread {
public Rect(JPanel b) {
box =
b;
}
public void move() {
if (!box.isVisible())
return;
Graphics
g = box.getGraphics();
g.setXORMode(box.getBackground());
g.drawRect(x, y,
XSIZE, YSIZE);
y += dy;
g.drawRect(x, y, XSIZE,
YSIZE);
g.dispose();
}
@Override
public void run() {
try
{
x=0;
y=0;
for (int i = 1; i <= 1000; i++)
{
move();
sleep(30);
}
} catch (InterruptedException e)
{
}
}
private JPanel box;
private static int XSIZE = 10;
private
static int YSIZE = 10;
private int x = 0;
private int y = 120;
private
int dy = 2;
}