Java – attach a single action listener to all buttons

I have a program with many buttons, all of which will perform the same function I wonder if there is a way to attach a single listener to all the existing jbuttons in the program

Solution

It's like:

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

public class CalculatorPanel extends JPanel
{
    private JTextField display;

    public CalculatorPanel()
    {
        Action numberAction = new AbstractAction()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                display.setCaretPosition( display.getDocument().getLength() );
                display.replaceSelection(e.getActionCommand());
            }
        };

        setLayout( new BorderLayout() );

        display = new JTextField();
        display.setEditable( false );
        display.setHorizontalAlignment(JTextField.RIGHT);
        add(display,BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel();
        buttonPanel.setLayout( new GridLayout(0,5) );
        add(buttonPanel,BorderLayout.CENTER);

        for (int i = 0; i < 10; i++)
        {
            String text = String.valueOf(i);
            JButton button = new JButton( text );
            button.addActionListener( numberAction );
            button.setBorder( new LineBorder(Color.BLACK) );
            button.setPreferredSize( new Dimension(50,50) );
            buttonPanel.add( button );

            Keystroke pressed = Keystroke.getKeystroke(text);
            InputMap inputMap = button.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
            inputMap.put(pressed,text);
            button.getActionMap().put(text,numberAction);
        }
    }

    private static void createAndShowUI()
    {
//      UIManager.put("Button.margin",new Insets(10,10,10) );

        JFrame frame = new JFrame("Calculator Panel");
        frame.setDefaultCloSEOperation( JFrame.EXIT_ON_CLOSE );
        frame.add( new CalculatorPanel() );
        frame.pack();
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
    }

    public static void main(String[] args)
    {
        EventQueue.invokelater(new Runnable()
        {
            public void run()
            {
                createAndShowUI();
            }
        });
    }
}

The action gets the source object from the event so that it knows which button was clicked

If you need to use if / else logic in an action, you should create a separate action If the code does not belong to an action, please do not enforce it