Removing listeners: remove the registered listeners. : Event Adapter « Swing Event « Java Tutorial

1. Java Tutorial
2. Swing Event
3. Event Adapter

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class RemoveListener {
  class ButtonListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      System.out.println(++count);
    }
  }
  JButton add = new JButton("+");
  JCheckBox active = new JCheckBox("Active listener");
  ButtonListener buttonlistener = new ButtonListener();
  int count = 0;

  public RemoveListener() {
    JPanel panel = new JPanel();
    active.addItemListener(new ItemListener() {
      public void itemStateChanged(ItemEvent event) {
        if (active.isSelected()) {
          add.addActionListener(buttonlistener);
        } else {
          add.removeActionListener(buttonlistener);
        }
      }
    });
    panel.add(add);
    panel.add(active);
    JFrame f = new JFrame();
    f.add(panel);

    f.setSize(310, 200);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
  }

  public static void main(String[] args) {
    new RemoveListener();
  }
}

15.2.Event Adapter
	15.2.1.	Using Adapter Classes
	15.2.2.	void java.awt.Toolkit.addAWTEventListener(AWTEventListener listener, long eventMask)
	15.2.3.	Multiple sources: A listener can be plugged into several sources.
	15.2.4.	Register several listeners for one event.
	15.2.5.	Removing listeners: remove the registered listeners.