countdown.java

Java程序设计技巧与开发实例附书源代码。

import java.awt.*;
import java.awt.event.*;

public class CountDown {
  ActionListener listener = null;
  Object source = null;
  int maxCount = 10;

  public CountDown(Object _source,int _maxCount) {
    maxCount = _maxCount;
    source = _source;
  }

  public void addActionListener(ActionListener newListener) {
    listener = AWTEventMulticaster.add(listener,newListener);
  }

  public void removeActionListener(ActionListener oldListener) {
    listener = AWTEventMulticaster.remove(listener,oldListener);
  }

  public void startCounting() {
    if (listener != null) {
      for (int i = maxCount; i >= 0; i--) {
        System.out.println("i: " + i);
      }
      System.out.println("Done. Generating event now ...");
      listener.actionPerformed(new ActionEvent(source,
                                               ActionEvent.ACTION_PERFORMED,
                                               "CountDown"));
    }
  }
}