Programming Forums > Application Development > Java

glopal · Mar 8th, 2007, 9:52 PM

Here, it should be a very simple program. When the mouse is clicked, it toggles a boolean value named hello. if hello is true, it draws hello on the screen. But it doesnt work, this mouse stuff is tricky. I click on the screen and nothing happens. Does it has to do with the thread?

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import java.applet.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;

public class MouseTest extends Applet implements Runnable, MouseListener, MouseMotionListener
{
	Thread loop;
	BufferedImage backbuffer;
	Graphics g2d;
	boolean hello;

	public void init()
	{
		backbuffer = new BufferedImage(100,100, BufferedImage.TYPE_INT_RGB);
        g2d = backbuffer.createGraphics();
	}

	public void start()
	{
	    loop = new Thread(this);
	    loop.start();

	    hello = false;
	}

	public void run()
	{
		Thread t = Thread.currentThread();
	    while (t == loop)
	    {

	    	try
	    	{
	            Thread.sleep(30);
	        }
	        catch(InterruptedException e) {
	            e.printStackTrace();
	        }
	        repaint();
	    }
    }
    public void paint(Graphics g)
    {
		 g.drawImage(backbuffer,0,0,this);
    }

    public void update(Graphics g)
    {
		if(hello)
			g2d.drawString("Hello",2,10);
		paint(g);
	}

    public void mousePressed(MouseEvent evt)
    {
	 	hello = !hello;
    }
    public void mouseReleased(MouseEvent evt) {}
    public void mouseDragged(MouseEvent evt) {}


    public void mouseEntered(MouseEvent evt) { }
    public void mouseExited(MouseEvent evt) { }
    public void mouseClicked(MouseEvent evt) { }
    public void mouseMoved(MouseEvent evt) { }

}

Anyone knows whats wrong?

Eric the Red · Mar 9th, 2007, 12:33 AM

I'm not too sure. However, its always a good idea to have something like this when you're implementing Runnable.

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public void destroy()
	{
		hello = false;
		loop = null;
		
	}

titaniumdecoy · Mar 9th, 2007, 12:53 AM

You don't need to use threads (explicitly, anyway) to listen for mouse clicks. Notice that the applet will not respond to mouse events unless you call addMouseListener with the applet itself (this). In order to update the display, you need to call repaint() in the mousePressed method, which will call the paint method. (Note that mouseClicked, rather than mousePressed, is probably what you want; it waits until the user has released the mouse button to fire the event.)

(Toggle Plain Text)

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class MouseTest extends Applet implements MouseListener
{
    boolean hello;

    public void init() {
        hello = false;
        addMouseListener(this);
    }
    
    public void paint(Graphics g)
    {
        if(hello)
            g.drawString("Hello", 2, 10);
    }

    public void mouseClicked(MouseEvent evt)
    {
        hello = !hello;
        repaint();
    }
   
    public void mousePressed(MouseEvent evt) { }
    public void mouseEntered(MouseEvent evt) { }
    public void mouseExited(MouseEvent evt) { }
    public void mouseReleased(MouseEvent evt) { }

}

andro · Mar 9th, 2007, 1:05 AM

I don't see him calling addMouseListener(this) anywhere.

glopal · Mar 9th, 2007, 12:05 PM

ya, thats what it is, I didnt add it in the init class, thx for the tips

ReggaetonKing · Mar 9th, 2007, 3:59 PM

Quote:

Originally Posted by glopal

ya, thats what it is, I didnt add it in the init class, thx for the tips

the init() method not class.

Mar 8th, 2007, 9:52 PM	#1
glopal Newbie Join Date: May 2005 Location: St. Andrews, Manitoba, Canada Posts: 9 Rep Power: 0	Java applet mouse event. Some trouble... Here, it should be a very simple program. When the mouse is clicked, it toggles a boolean value named hello. if hello is true, it draws hello on the screen. But it doesnt work, this mouse stuff is tricky. I click on the screen and nothing happens. Does it has to do with the thread? (Toggle Plain Text) import java.applet.; import java.awt.; import java.awt.image.; import java.awt.event.; public class MouseTest extends Applet implements Runnable, MouseListener, MouseMotionListener { Thread loop; BufferedImage backbuffer; Graphics g2d; boolean hello; public void init() { backbuffer = new BufferedImage(100,100, BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); } public void start() { loop = new Thread(this); loop.start(); hello = false; } public void run() { Thread t = Thread.currentThread(); while (t == loop) { try { Thread.sleep(30); } catch(InterruptedException e) { e.printStackTrace(); } repaint(); } } public void paint(Graphics g) { g.drawImage(backbuffer,0,0,this); } public void update(Graphics g) { if(hello) g2d.drawString("Hello",2,10); paint(g); } public void mousePressed(MouseEvent evt) { hello = !hello; } public void mouseReleased(MouseEvent evt) {} public void mouseDragged(MouseEvent evt) {} public void mouseEntered(MouseEvent evt) { } public void mouseExited(MouseEvent evt) { } public void mouseClicked(MouseEvent evt) { } public void mouseMoved(MouseEvent evt) { } } import java.applet.; import java.awt.; import java.awt.image.; import java.awt.event.; public class MouseTest extends Applet implements Runnable, MouseListener, MouseMotionListener { Thread loop; BufferedImage backbuffer; Graphics g2d; boolean hello; public void init() { backbuffer = new BufferedImage(100,100, BufferedImage.TYPE_INT_RGB); g2d = backbuffer.createGraphics(); } public void start() { loop = new Thread(this); loop.start(); hello = false; } public void run() { Thread t = Thread.currentThread(); while (t == loop) { try { Thread.sleep(30); } catch(InterruptedException e) { e.printStackTrace(); } repaint(); } } public void paint(Graphics g) { g.drawImage(backbuffer,0,0,this); } public void update(Graphics g) { if(hello) g2d.drawString("Hello",2,10); paint(g); } public void mousePressed(MouseEvent evt) { hello = !hello; } public void mouseReleased(MouseEvent evt) {} public void mouseDragged(MouseEvent evt) {} public void mouseEntered(MouseEvent evt) { } public void mouseExited(MouseEvent evt) { } public void mouseClicked(MouseEvent evt) { } public void mouseMoved(MouseEvent evt) { } } Anyone knows whats wrong?

Mar 9th, 2007, 12:33 AM	#2
Eric the Red Hobbyist Programmer Join Date: Feb 2006 Posts: 214 Rep Power: 0	I'm not too sure. However, its always a good idea to have something like this when you're implementing Runnable. (Toggle Plain Text) public void destroy() { hello = false; loop = null; } public void destroy() { hello = false; loop = null; } __________________ Death smiles at us all. All a man can do is smile back.

Mar 9th, 2007, 12:53 AM	#3
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 839 Rep Power: 3	You don't need to use threads (explicitly, anyway) to listen for mouse clicks. Notice that the applet will not respond to mouse events unless you call addMouseListener with the applet itself (this). In order to update the display, you need to call repaint() in the mousePressed method, which will call the paint method. (Note that mouseClicked, rather than mousePressed, is probably what you want; it waits until the user has released the mouse button to fire the event.) (Toggle Plain Text) import java.applet.; import java.awt.; import java.awt.event.; public class MouseTest extends Applet implements MouseListener { boolean hello; public void init() { hello = false; addMouseListener(this); } public void paint(Graphics g) { if(hello) g.drawString("Hello", 2, 10); } public void mouseClicked(MouseEvent evt) { hello = !hello; repaint(); } public void mousePressed(MouseEvent evt) { } public void mouseEntered(MouseEvent evt) { } public void mouseExited(MouseEvent evt) { } public void mouseReleased(MouseEvent evt) { } } import java.applet.; import java.awt.; import java.awt.event.; public class MouseTest extends Applet implements MouseListener { boolean hello; public void init() { hello = false; addMouseListener(this); } public void paint(Graphics g) { if(hello) g.drawString("Hello", 2, 10); } public void mouseClicked(MouseEvent evt) { hello = !hello; repaint(); } public void mousePressed(MouseEvent evt) { } public void mouseEntered(MouseEvent evt) { } public void mouseExited(MouseEvent evt) { } public void mouseReleased(MouseEvent evt) { } } Last edited by titaniumdecoy; Mar 9th, 2007 at 1:05 AM.

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Mar 9th, 2007, 1:05 AM	#4
andro Professional Programmer Join Date: Oct 2005 Location: California Posts: 294 Rep Power: 3	I don't see him calling addMouseListener(this) anywhere.

Mar 9th, 2007, 12:05 PM	#5
glopal Newbie Join Date: May 2005 Location: St. Andrews, Manitoba, Canada Posts: 9 Rep Power: 0	ya, thats what it is, I didnt add it in the init class, thx for the tips

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Programming Forums > Application Development > Java

Java applet mouse event. Some trouble...