Add ActionListener to JButton

[Thomas Webb]

Hi, i have a JPanel with GridLayout(20,20) and i am filling it with buttons like this:

for (int i = 0; i < 400; i++)
{
gamePanel.add(new JButton("" + i));
}

I just want to know how i would add an action listener to each button and then identify each button individually when clicked. Thanks.

[Michael Dunn]

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
 
class Testing extends JFrame
{
  public Testing()
  {
    setLocation(300,200);
    setSize(600,400);
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    JPanel gamePanel = new JPanel(new GridLayout(20,20));
    gamePanel.setPreferredSize(new Dimension(1200,1200));
    for (int x = 0; x < 400; x++)
    {
      JButton btn = new JButton("" + x);
      final int selectedIndex = x;
      btn.addActionListener(new ActionListener(){
        public void actionPerformed(ActionEvent ae){
          JOptionPane.showMessageDialog(getContentPane(),"I am button "+selectedIndex);}});
      gamePanel.add(btn);
    }
    JScrollPane sp = new JScrollPane(gamePanel);
    getContentPane().add(sp);
  }
  public static void main(String[] args){new Testing().setVisible(true);}
}

[luc comeau]

hi,
i never did like that way that was shown above...i hate cramming code like that ...i duno just a preference thing though..
what i always to is ,
1:make your class implement the ActionListener interface
2:you must then have an ActionPerformed method that looks like this
--->public void actionPerformed(ActionEvent e)
a short short example may help

public class Weeee implements ActionListener{
.
.
.private JButton b1;
 
//initialize button and add action listener
b1= new button("this is a button");
b1.addActionListener(this);
 
//now ur set for the actionPerformed method
public void actionPerformed(ActionEvent e){
 
if(e.getSource()==b1){
do stuff;
}

you can do this for as many buttons as you want, and just folow the same basic outline i have shown.Hope it helps some, or atleast gives you another perspective.