Event source and listener

  

import java.util.ArrayList;
import java.util.EventListener;
import java.util.EventObject;

abstract class TestEventSource {
  public abstract void addListener(TestEventListener l);

  public abstract void removeListener(TestEventListener l);

  public abstract void fireEvent(java.util.EventObject o);

  public void test() {
    addListener(new TestEventListener("A"));
    fireEvent(new java.util.EventObject(this));
  }
}

class TestEventListener implements EventListener {
  String id;

  public TestEventListener(String id) {
    this.id = id;
  }

  public void handleEvent(EventObject o) {
    System.out.println(id + " called");
    if (id.equals("C")) {
      ((TestEventSource) o.getSource()).removeListener(this);
    }
  }
}

public class Main extends TestEventSource {
  ArrayList listeners = new ArrayList();
  public void addListener(TestEventListener l) {
    listeners.add(l);
  }
  public void removeListener(TestEventListener l) {
    listeners.remove(l);
  }
  public void fireEvent(EventObject o) {
    for (int i = 0; i < listeners.size(); i++) {
      TestEventListener l = (TestEventListener) listeners.get(i);
      l.handleEvent(o);
    }
  }
  public static void main(String[] args) {
    Main pfles = new Main();
    pfles.test();
  }

}

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5.	Adding an InputMap to a Component
6.	Multiple sources: A listener can be plugged into several sources.
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10.	JComponent.WHEN_IN_FOCUSED_WINDOW
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Event source and listener : Event Queue « Event « Java

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