beeper.java

该程序是用jbuilder制作

package myoven.beeper;

public class Beeper {

  private static Beeper instance;

  public static Beeper getInstance(){
    if(instance==null){
      instance = new Beeper();
      System.out.println("new a beeper");
    }
    return instance;//返回唯一实例
  }

  public Beeper() {
  }
  public void beep(){
    java.awt.Toolkit.getDefaultToolkit().beep();
  }

}