Java/Event/Customized Event

ActionMap javax.swing.JComponent.getActionMap()

 
import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
public class Main {
  public static void main(String[] argv) throws Exception {
    JButton component = new JButton();
    MyAction action = new MyAction();
    component.getActionMap().put(action.getValue(Action.NAME), action);
  }
}
class MyAction extends AbstractAction {
  public MyAction() {
    super("my action");
  }
  public void actionPerformed(ActionEvent e) {
    System.out.println("hi");
  }
}

Creating a Custom Event

 

import java.util.EventListener;
import java.util.EventObject;
import javax.swing.event.EventListenerList;
class MyEvent extends EventObject {
  public MyEvent(Object source) {
    super(source);
  }
}
interface MyEventListener extends EventListener {
  public void myEventOccurred(MyEvent evt);
}
class MyClass {
  protected EventListenerList listenerList = new EventListenerList();
  public void addMyEventListener(MyEventListener listener) {
    listenerList.add(MyEventListener.class, listener);
  }
  public void removeMyEventListener(MyEventListener listener) {
    listenerList.remove(MyEventListener.class, listener);
  }
  void fireMyEvent(MyEvent evt) {
    Object[] listeners = listenerList.getListenerList();
    for (int i = 0; i < listeners.length; i = i+2) {
      if (listeners[i] == MyEventListener.class) {
        ((MyEventListener) listeners[i+1]).myEventOccurred(evt);
      }
    }
  }
}
public class Main {
  public static void main(String[] argv) throws Exception {
    MyClass c = new MyClass();
    c.addMyEventListener(new MyEventListener() {
      public void myEventOccurred(MyEvent evt) {
        System.out.println("fired");
      }
    });
  }
}

Customized Event

 
import java.awt.AWTEvent;
import java.awt.ruponent;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.EventListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
public class CustomEventPanel extends JPanel implements TimerListener {
  private int currentValue = 10;
    JProgressBar bar = new JProgressBar(1,100);
  public CustomEventPanel() {
    TimerComponent t = new TimerComponent(1000);
    t.addTimerListener(this);
    add(bar);
  }
  public void timeElapsed(TimerEvent evt) {
    currentValue += 10;
    bar.setValue(currentValue);
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setTitle("Customized Event");
    frame.setSize(300, 80);
    frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    Container contentPane = frame.getContentPane();
    contentPane.add(new CustomEventPanel());
    frame.show();
  }
}
interface TimerListener extends EventListener {
  public void timeElapsed(TimerEvent evt);
}
class TimerComponent extends Component implements Runnable {
  private int interval;
  private TimerListener listener;
  private static EventQueue evtq;
  public TimerComponent(int i) {
    interval = i;
    Thread t = new Thread(this);
    t.start();
    evtq = Toolkit.getDefaultToolkit().getSystemEventQueue();
    enableEvents(0);
  }
  public void addTimerListener(TimerListener l) {
    listener = l;
  }
  public void run() {
    while (true) {
      try {
        Thread.sleep(interval);
      } catch (InterruptedException e) {
      }
      TimerEvent te = new TimerEvent(this);
      evtq.postEvent(te);
    }
  }
  public void processEvent(AWTEvent evt) {
    if (evt instanceof TimerEvent) {
      if (listener != null)
        listener.timeElapsed((TimerEvent) evt);
    } else
      super.processEvent(evt);
  }
}
class TimerEvent extends AWTEvent {
  public static final int TIMER_EVENT = AWTEvent.RESERVED_ID_MAX + 5555;
  public TimerEvent(TimerComponent t) {
    super(t, TIMER_EVENT);
  }
}

implements AWTEventListener

 
import java.awt.AWTEvent;
import java.awt.Toolkit;
import java.awt.event.AWTEventListener;
import java.awt.event.ActionEvent;
import java.awt.event.ruponentEvent;
import java.awt.event.WindowEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
public class Main implements AWTEventListener {
  public void eventDispatched(AWTEvent evt) {
    if (evt.getID() == WindowEvent.WINDOW_OPENED) {
      ComponentEvent cev = (ComponentEvent) evt;
      if (cev.getComponent() instanceof JFrame) {
        System.out.println("event: " + evt);
        JFrame frame = (JFrame) cev.getComponent();
        loadSettings(frame);
      }
    }
  }
  public static void loadSettings(JFrame frame) {
    System.out.println("loading");
  }
  public static void saveSettings() {
    System.out.println("saving");
  }
  public static void main(String[] args) throws Exception {
    Toolkit tk = Toolkit.getDefaultToolkit();
    final Main main = new Main();
    tk.addAWTEventListener(main, AWTEvent.WINDOW_EVENT_MASK);
    final JFrame frame = new JFrame("");
    frame.setName("your frame");
    JMenuBar mb = new JMenuBar();
    JMenu menu = new JMenu("File");
    menu.add(new AbstractAction("Quit") {
      public void actionPerformed(ActionEvent evt) {
        try {
          main.saveSettings();
          System.exit(0);
        } catch (Exception ex) {
          System.out.println(ex);
        }
      }
    });
    mb.add(menu);
    frame.setJMenuBar(mb);
    frame.pack();
    frame.setVisible(true);
  }
}

int java.awt.AWTEvent.getID()

 
import java.awt.AWTEvent;
import java.awt.Toolkit;
import java.awt.event.AWTEventListener;
import java.awt.event.ActionEvent;
import java.awt.event.ruponentEvent;
import java.awt.event.WindowEvent;
import javax.swing.AbstractAction;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
public class Main implements AWTEventListener {
  public void eventDispatched(AWTEvent evt) {
    if (evt.getID() == WindowEvent.WINDOW_OPENED) {
      ComponentEvent cev = (ComponentEvent) evt;
      if (cev.getComponent() instanceof JFrame) {
        System.out.println("event: " + evt);
        JFrame frame = (JFrame) cev.getComponent();
        loadSettings(frame);
      }
    }
  }
  public static void loadSettings(JFrame frame) {
    System.out.println("loading");
  }
  public static void saveSettings() {
    System.out.println("saving");
  }
  public static void main(String[] args) throws Exception {
    Toolkit tk = Toolkit.getDefaultToolkit();
    final Main main = new Main();
    tk.addAWTEventListener(main, AWTEvent.WINDOW_EVENT_MASK);
    final JFrame frame = new JFrame("");
    frame.setName("your frame");
    JMenuBar mb = new JMenuBar();
    JMenu menu = new JMenu("File");
    menu.add(new AbstractAction("Quit") {
      public void actionPerformed(ActionEvent evt) {
        try {
          main.saveSettings();
          System.exit(0);
        } catch (Exception ex) {
          System.out.println(ex);
        }
      }
    });
    mb.add(menu);
    frame.setJMenuBar(mb);
    frame.pack();
    frame.setVisible(true);
  }
}

Removing listeners: remove the registered listeners.

 
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();
  }
}