How to use an action listener to check if a certain button was clicked?

Question

I have 4 lists of buttons arranged into a column in my program. As of now I have 4 loops that check to see if a button has been clicked or not. Is there a simple way to check if any button has been clicked instead of looping through each list to see if that certain button was clicked. There must be an easier way to check if "actionSource == anybutton"...

Answer 1

Use anonymous inner classes for each button:

JButton button = new JButton("Do Something");
button.addActionListener( new ActionListener()
{
    @Override
    public void actionPerformed(ActionEvent e)
    {
        System.out.println("Do Something Clicked");
    }
});

Or if your logic is related, then you can share a listener:

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

public class ButtonCalculator extends JFrame implements ActionListener
{
    private JButton[] buttons;
    private JTextField display;

    public ButtonCalculator()
    {
        display = new JTextField();
        display.setEditable( false );
        display.setHorizontalAlignment(JTextField.RIGHT);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout( new GridLayout(0, 5) );
        buttons = new JButton[10];

        for (int i = 0; i < buttons.length; i++)
        {
            String text = String.valueOf(i);
            JButton button = new JButton( text );
            button.addActionListener( this );
            button.setMnemonic( text.charAt(0) );
            buttons[i] = button;
            buttonPanel.add( button );
        }

        getContentPane().add(display, BorderLayout.NORTH);
        getContentPane().add(buttonPanel, BorderLayout.SOUTH);
        setResizable( false );
    }

    public void actionPerformed(ActionEvent e)
    {
        JButton source = (JButton)e.getSource();
        display.replaceSelection( source.getActionCommand() );
    }

    public static void main(String[] args)
    {
        UIManager.put("Button.margin", new Insets(10, 10, 10, 10) );
        ButtonCalculator frame = new ButtonCalculator();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }
}