Help understanding why mouse event seems to be registering twice.

[Felix Chien]

I'm working on a applet that in part will update the user with the amount of times they have clicked and it seems that the variable I set 'count' is doing: count += 2; instead of what I put down as: count ++; I need help understanding why that is.

import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
import java.util.ArrayList;
import javax.swing.*;

public class pointTest extends Applet
{
  private int xMP = 200, yMP = 200, count =0;
  private int counter = 0;
  private ArrayList<Point> pointList = new ArrayList<Point>();
  private int [] xMotherShip = {xMP, xMP +35, xMP +20, xMP + 50, xMP -50, xMP-20,xMP -35};
  private int [] yMotherShip = {yMP -20, yMP +10, yMP+10, yMP +30, yMP +30, yMP +10, yMP +10};	

  public void paint (Graphics page)
  {
    init(page);
    page.fillPolygon (xMotherShip, yMotherShip, xMotherShip.length);
	 page.drawString("Clicks: " + counter, 10, 10); 
  }

  
  public void init(Graphics page)
  {
    setBackground (Color.black);
	 page.setColor (Color.yellow);
  	 setPreferredSize(new Dimension(500, 500));
	 UserClickedListener listener2 = new UserClickedListener();
	 addMouseListener(listener2);
  }
  
    
  private class UserClickedListener implements MouseListener
  {
	 public void mouseClicked(MouseEvent e) {
	   counter ++;
		
		System.out.println(counter);
    }
	 public void mouseReleased(MouseEvent e) {}
	 public void mouseEntered(MouseEvent e){}
	 public void mouseExited(MouseEvent e){}
    public void mousePressed(MouseEvent e){}
  }
}	 

Any help is appreciated.

[Rob Spoor]

Don't call init from your paint method. The paint method is called quite often, in some applets even multiple times per second. That means that you will do all that initialization each and every time. Instead, use the "regular" init method:

public void paint(Graphics page)   
{   
    //init(page);   
    page.setColor(Color.yellow);
    page.fillPolygon (xMotherShip, yMotherShip, xMotherShip.length);   
    page.drawString("Clicks: " + counter, 10, 10);    
}

public void init() // part of the Applet API, called only once by the browser / applet viewer
{   
    setBackground (Color.black);   
    setPreferredSize(new Dimension(500, 500));   
    UserClickedListener listener2 = new UserClickedListener();   
    addMouseListener(listener2);   
}

Note how I did move the changing of the color of page to the paint methods; that is the one thing from your old init method that you do want to occur during each paint.

[Felix Chien]

Ah, Thanks Rob! I was quite confused... That fix worked perfectly =D

[Rob Spoor]

You're welcome.