Java

HELP with code

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Join Date: Aug 2009

Posts: 25

Reputation: treyd is an unknown quantity at this point

Solved Threads: 0

treyd

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HELP with code

Nov 3rd, 2009

I have to write a program that has a tic tac toe board. When you click it, it should go from one image to another. My code compiles fine, but it doesnt run. I get some errors:

Exception in thread "main" java.lang.NullPointerException
at TicTacToe3.<init>(TicTacToe3.java:27)
at TicTacToe3.main(TicTacToe3.java:41)

My code:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class TicTacToe3 extends JFrame{
 
JButton x;
ImageIcon imageO;
JButton o;
ImageIcon imageX;
JButton[][] button = new JButton[3][3];
int i;
int j;
 
TicTacToe3(){
  super("TicTacToe2");
  setSize(600, 300);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  setLayout(new GridLayout(3,3));
 
  JButton[][] button = new JButton[3][3];
    for(int i=0;i<3;i++){
    for(int j=0;j<3;j++){
    button[i][j].addMouseListener(new ButtonListener());
    add(button[i][j]);
}
}
 
    ImageIcon imageX = new ImageIcon("kate.jpg"); 
    button[i][j].setIcon(imageX);
 
 
  setVisible(true);
}
 
public static void main(String args[]) {
  TicTacToe3 e = new TicTacToe3();
} 
 
 
 class ButtonListener extends MouseAdapter {
   public	void mouseClicked(MouseEvent e){
    ImageIcon imageO = new ImageIcon("jon.jpg");
    button[i][j].setIcon(imageO);
 
         }
      }
   }
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TicTacToe3 extends JFrame{

JButton x;
ImageIcon imageO;
JButton o;
ImageIcon imageX;
JButton[][] button = new JButton[3][3];
int i;
int j;

TicTacToe3(){
  super("TicTacToe2");
  setSize(600, 300);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  setLayout(new GridLayout(3,3));

  JButton[][] button = new JButton[3][3];
    for(int i=0;i<3;i++){
    for(int j=0;j<3;j++){
    button[i][j].addMouseListener(new ButtonListener());
    add(button[i][j]);
}
}

    ImageIcon imageX = new ImageIcon("kate.jpg"); 
    button[i][j].setIcon(imageX);


  setVisible(true);
}

public static void main(String args[]) {
  TicTacToe3 e = new TicTacToe3();
} 


 class ButtonListener extends MouseAdapter {
   public	void mouseClicked(MouseEvent e){
    ImageIcon imageO = new ImageIcon("jon.jpg");
    button[i][j].setIcon(imageO);
            
         }
      }
   }

•

Join Date: May 2007

Posts: 4,508

Reputation: Ezzaral has a brilliant future

Solved Threads: 522

Ezzaral

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Industrious Poster

Nov 3rd, 2009

You have to actually create the JButtons in your array. You have only declared the array of references with this statement

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
JButton[][] button = new JButton[3][3];
JButton[][] button = new JButton[3][3];

You must still initialize those objects by adding

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
button[i][j] = new JButton();
button[i][j] = new JButton();

in your loop before you try to do anything with them.

Last edited by Ezzaral; Nov 3rd, 2009 at 3:40 pm.

•

Join Date: Aug 2009

Posts: 25

Reputation: treyd is an unknown quantity at this point

Solved Threads: 0

treyd

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Nov 3rd, 2009

Thanks! That makes perfect sense. That solves the whole window popping up thing, but I have still am having two probelms. My initial image icon only shows in the first button. Also, when I click a buton I get a long list of errors. Something like:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException

Any ideas?
Thanks again

•

Join Date: Aug 2009

Posts: 25

Reputation: treyd is an unknown quantity at this point

Solved Threads: 0

treyd

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Nov 3rd, 2009

Okay. I got all the images in the right spot. Now I just need to get them to switch to the other image.

New Code:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class TicTacToe3 extends JFrame{
 
JButton x;
ImageIcon imageO;
JButton o;
ImageIcon imageX;
JButton[][] button = new JButton[3][3];
int i;
int j;
 
TicTacToe3(){
  super("TicTacToe2");
  setSize(600, 300);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  setLayout(new GridLayout(3,3));
 
  JButton[][] button = new JButton[3][3];
    for(int i=0;i<3;i++){
    for(int j=0;j<3;j++){
    button[i][j] = new JButton();
    ImageIcon imageX = new ImageIcon("kate.jpg"); 
    button[i][j].setIcon(imageX);
    button[i][j].addMouseListener(new ButtonListener());
 
    add(button[i][j]);
}
}
 
 
 
    setVisible(true);
}
 
public static void main(String args[]) {
  TicTacToe3 e = new TicTacToe3();
} 
 
 
 class ButtonListener extends MouseAdapter {
   public	void mouseClicked(MouseEvent e){
    ImageIcon imageO = new ImageIcon("jon.jpg");
    button[i][j].setIcon(imageO);
 
         }
      }
   }
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TicTacToe3 extends JFrame{

JButton x;
ImageIcon imageO;
JButton o;
ImageIcon imageX;
JButton[][] button = new JButton[3][3];
int i;
int j;

TicTacToe3(){
  super("TicTacToe2");
  setSize(600, 300);
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLocationRelativeTo(null);
  setLayout(new GridLayout(3,3));

  JButton[][] button = new JButton[3][3];
    for(int i=0;i<3;i++){
    for(int j=0;j<3;j++){
    button[i][j] = new JButton();
    ImageIcon imageX = new ImageIcon("kate.jpg"); 
    button[i][j].setIcon(imageX);
    button[i][j].addMouseListener(new ButtonListener());
       
    add(button[i][j]);
}
}

    

    setVisible(true);
}

public static void main(String args[]) {
  TicTacToe3 e = new TicTacToe3();
} 


 class ButtonListener extends MouseAdapter {
   public	void mouseClicked(MouseEvent e){
    ImageIcon imageO = new ImageIcon("jon.jpg");
    button[i][j].setIcon(imageO);
            
         }
      }
   }

•

Join Date: May 2007

Posts: 4,508

Reputation: Ezzaral has a brilliant future

Solved Threads: 522

Ezzaral

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Industrious Poster

Nov 3rd, 2009

Your listener is setting the icon on whichever button i and j corresponds to

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
button[i][j].setIcon(imageO);
button[i][j].setIcon(imageO);

What you really want to do is getSource() from the mouse event and cast that to a JButton and set it's image.

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
JButton clickedButton = (JButton)e.getSource();
JButton clickedButton = (JButton)e.getSource();

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Join Date: Aug 2009

Posts: 25

Reputation: treyd is an unknown quantity at this point

Solved Threads: 0

treyd

Offline

Light Poster

Nov 3rd, 2009

Where do I put that?

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Join Date: Aug 2009

Posts: 25

Reputation: treyd is an unknown quantity at this point

Solved Threads: 0

treyd

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Light Poster

Nov 3rd, 2009

When I take out:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
button[i][j].setIcon(imageO);
button[i][j].setIcon(imageO);

and add:

 Help with Code Tags 
 Java Syntax (Toggle Plain Text) 
JButton clickedButton = (JButton)e.getSource();
JButton clickedButton = (JButton)e.getSource();