I am having trouble making use of a MouseMotionListener to make some card images be able to be dragged around the screen. What this program does is show a table of cards in a random order. The user will be able to drag any of the card images and move it anywhere in the window and have it stay there.

The problem I'm having is that the listener does not seem to ever get called and I cannot figure out why

mouse listener class

import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

public class MouseListener extends Card implements MouseMotionListener 
	{

	public void mousePressed(MouseEvent arg0) {
	}

	@Override
	public void mouseDragged(MouseEvent arg0) 
	{

	// TODO Auto-generated method stub
	super.setx(arg0.getX());
	super.sety(arg0.getY());
	repaint();
	}

	@Override
	public void mouseMoved(MouseEvent arg0) 
	{
		// TODO Auto-generated method stub
	}
}

the card class

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

public class Card extends JPanel 
	{

	private ImageIcon img= null;
	private int x,y;
	

	 public void setx(int X)
	{
	x=X;	
	}
	 
	 public void sety(int Y)
		{
		y=Y;	
		}

	
	public Card(ImageIcon icon)
		{
		this.addMouseMotionListener(new MouseListener());
		this.img = icon;
		x=0;
		y=0;
		
		}
	
	protected Card()
	{
	}
	
	public void paint(Graphics g,int X, int Y) 
		{
		img.paintIcon(this, g, X+x, Y+y);
		}
	}

and main

public static void main(String[] args)
    {
		/**
		 *@param  args		Not used for anything
		 */
		
        //load the card images
        final ImageIcon blank = new ImageIcon("cardImages/gray.gif");
        
        CardDeck deck = new CardDeck();
    	deck.shuffle();
    	
    	//take all the cards off the deck now
    	final Card[] cardIcon = new Card[52];
    	
    	for (int i = 0; i < 52; i++)
    		cardIcon[i]= deck.getCard();
        

        //create a panel displaying the card image
       JPanel panel = new JPanel()
        {
           
			private static final long serialVersionUID = 1L;

			//paintComponent is called automatically by the JRE whenever
            //the panel needs to be drawn or redrawn
            public void paintComponent(Graphics g) 
            	{
            	
            	int x = 0,y = 20;	//offsets used for drawing the cards
                super.paintComponent(g);

                //paint the blank cards: 
                blank.paintIcon(this, g, 20, 20);
                blank.paintIcon(this, g, 20, 130);
                blank.paintIcon(this, g, 20, 240);
                blank.paintIcon(this, g, 20, 350);
                
                //paint the other cards
                for (int i = 0; i <52; i++)
                	{
                	if (i == 13)		//start row two
                		{
                		x = 0;
                		y = 130;
                		}
                	
                	else if (i == 26)	//start row 3
                		{
                		x = 0;
                		y = 240;
                		}

                	else if (i == 39)	//start row 4
                		{
                		x = 0;
                		y = 350;
                		}
                	
                	x += 80;
                	//cardIcon[i].paintIcon(this, g, x+20, y);
                	cardIcon[i].setEnabled(true);
                	cardIcon[i].paint(g, x+20, y);

                	//cardIcon[i].setFocusable(true);
                	//cardIcon[i].setRequestFocusEnabled(isVisible());
                	}
                		
                }
        	};
        		


        //create & make visible a JFrame to contain the panel
        JFrame window = new JFrame("Cards");
        panel.setBackground(new Color(90,190,90));
        window.add(panel);
        window.setPreferredSize(new Dimension(1180,500));
        window.pack();
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setVisible(true);
    }
}

The mouse listener is the only part of this code that doesn't work

MouseListener is a interface in the Java API, so it's not a good name to use for yours. It's worth changing it, just in case.

Edited 6 Years Ago by JamesCherrill: n/a

public class MouseListener extends Card implements MouseMotionListener

MouseListener is already a predefined infce so that you change it..

another thing don't use words in java those are predefined keywords,interface..etc..

I changed its name to 'myMouseListener' now, its still the same story

Edited 6 Years Ago by FotG2: n/a

OK, had another look, try this idea for size:
Your listener class extends Card, but you add a new instance of that class as you listening instance. Althiough you call super.etc in that class, it doesn't extend any actual instance of a card, so that does nothing.
Perhaps you should move your mouse methods into the Card class, then change the constructor to
addMouseMotionListener(this);

I still seem to have the same problem, using breakpoints and debugging mode, I still see that mouseDragged never gets called.

my card class now looks like

import javax.swing.*;
import java.awt.*;		//for some reason this doesn't work
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

public class Card extends JPanel implements MouseMotionListener 
	{

	private static final long serialVersionUID = 1L;
	private ImageIcon img= null;
	private int x,y;			//paint offsets
	
	
	public Card(ImageIcon icon)
		{
		addMouseMotionListener(this);
		this.img = icon;
		x=0;
		y=0;
		}
	
	
	
	public void paint(Graphics g,int X, int Y) 
		{
		img.paintIcon(this, g, X+x, Y+y);
		}
	
	public void mousePressed(MouseEvent arg0) {
	}

	
	@Override
	public void mouseDragged(MouseEvent arg0) 
		{
		// TODO Auto-generated method stub
		x = arg0.getX();
		y = arg0.getY();
		repaint();
		}

	
	@Override
	public void mouseMoved(MouseEvent arg0) 
		{
		// TODO Auto-generated method stub
		}
	}

I've been gtrying to understand your code - which is quite weird.
Card extends JPanel, but you don't seem to add a Card to any visible container. Card just looks like a holder for the paint(...) method that you invoke from somewhere else to paint the card into a JPanel in the main window. It seems to me that the main window has card images drawn in it, but doesn't actually contain any Card objects. In which case no listeners will ever be called for a Card.
Maybe I have this all wrong, in which case I'm sorry and please ignore this.

I really don't know of any other way to do this, the java swing documentation and examples that I've found don't really help me at all.

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