Re: need help or explanation
On 12/22/2009 4:56 PM, Dave wrote:
I'm new to Java and I'm running into a problem I can't figure out.
I have a menu on a screen and I'm also drawing a moving filled oval on it.
When I run the program, I end up with a double menu line. It's as if
the first repaint is shifting the whole display down the size of the menu
line.
The first oval is also shifted down the size of the menu line. The rest of
the oval repaints seem to be where they should be.
Even though I have 2 menu lines, only the top menu works when I
click on it. When I click on "Menu1", I get 2 "first entry" items, one
below the other. See Menu example below.
------------------------------------------------
Menu1 (this menu works when I click on it)
------------------------------------------------
Menu1 (this menu doesn't do anything)
------------------------------------------------
-----------------------------------------------------------
Menu1 (when I click the top menu, I get 2 first entries)
-----------------------------------------------------------
first entry (the lower Menu1 is written over)
-----------------------------------------------------------
first entry
-----------------------------------------------------------
The bad part is, when I run this program at work, it works like
it's supposed to. When I run it at home, I get the double menu.
I haven't tried the program on any other PC's yet.
I'm using JCreator LE version 3.50.013 both at work and home.
My Java version is 1.6.0_17-b04 both at work and home.
I have XP Pro at work, but just XP at home.
Here is the program.
import javax.swing.*;
import java.awt.*;
public class graph1
{
int x = 70;
int y = 70;
public static void main(String[] args)
{
graph1 gui = new graph1();
gui.go();
}
public void go()
{
JMenuBar mBar = new JMenuBar();
JMenu mMenu1 = new JMenu("Menu1");
JMenuItem mItem = new JMenuItem("first entry");
mBar.add(mMenu1);
mMenu1.add(mItem);
JFrame frame = new JFrame("Graph1");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setJMenuBar(mBar);
MyPaint mp = new MyPaint();
frame.getContentPane().add(mp);
frame.setSize(600,600);
frame.setVisible(true);
for ( int i = 0; i< 200; i++ )
{
++x;
++y;
try
{
Thread.sleep(200);
}
catch(Exception ex) {}
mp.repaint();
}
}
class MyPaint extends JPanel
{
public void paintComponent(Graphics g)
{
g.setColor(Color.green);
g.fillOval(x,y,40,40);
}
}
}
Minimum to make your work:
import javax.swing.*;
import java.awt.*;
public class graph1 implements Runnable
{
int x = 70;
int y = 70;
MyPaint mp;
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable() {
public void run() {
graph1 gui = new graph1();
gui.go();
new Thread(gui).start();
}
});
}
public void go()
{
JMenuBar mBar = new JMenuBar();
JMenu mMenu1 = new JMenu("Menu1");
JMenuItem mItem = new JMenuItem("first entry");
mBar.add(mMenu1);
mMenu1.add(mItem);
JFrame frame = new JFrame("Graph1");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setJMenuBar(mBar);
mp = new MyPaint();
frame.getContentPane().add(mp);
frame.setSize(600,600);
frame.setVisible(true);
}
public void run() {
for ( int i = 0; i < 200; i++ )
{
++x;
++y;
try
{
Thread.sleep(200);
}
catch(Exception ex) {}
mp.repaint();
}
}
class MyPaint extends JPanel
{
public void paintComponent(Graphics g)
{
g.setColor(getBackground());
g.fillRect(0,0,getWidth(),getHeight());
g.setColor(Color.green);
g.fillOval(x,y,40,40);
}
}
}
Better example and a few goodies thrown in:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class GraphOne extends JPanel implements ActionListener, Runnable {
private int x,y;
private int deltaX = 1;
private int deltaY = 1;
public GraphOne() {
setBackground(Color.WHITE);
setForeground(Color.GREEN);
setPreferredSize(new Dimension(400,300));
}
public void actionPerformed(ActionEvent ae) {
String ac = ae.getActionCommand();
if (ac.equals("Quit"))
System.exit(0);
}
public void run() {
while (true) {
x += deltaX;
y += deltaY;
if (x >= getWidth()-40 || x <= 0)
deltaX = -deltaX;
if (y >= getHeight()-40 || y <=0)
deltaY = -deltaY;
repaint();
try { Thread.sleep(10);
} catch (InterruptedException ie) { }
}
}
public void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(getBackground());
g2d.fillRect(0,0,getWidth(),getHeight());
g2d.setColor(getForeground());
g2d.fillOval(x,y,40,40);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame("GraphOne");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
GraphOne g1 = new GraphOne();
JMenuBar mb = new JMenuBar();
JMenu file = new JMenu("File");
JMenuItem quit = new JMenuItem("Quit");
f.setJMenuBar(mb);
mb.add(file);
file.add(quit);
quit.addActionListener(g1);
f.add(g1,BorderLayout.CENTER);
f.pack();
f.setVisible(true);
new Thread(g1).start();
}
});
}
}
--
Knute Johnson
email s/nospam/knute2010/
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