singletonpattern.java

有一个接口,用抽象类实现它的部分功能,再用实现类继承抽象类,实现其它没实现的接口方法

package cn.edu.csu.oo.staticoper;

import java.awt.*;
public class SingletonPattern {
  /*
  private static SingletonPattern sp;
  double r;
  private SingletonPattern(){
    r = Math.random();
  }
  
  public static SingletonPattern newInstance(){
    if(sp == null){
      sp =  new SingletonPattern();
    }
    return sp;
  }
  
  /**
   * @param args
   */
  /*
  public static void main(String[] args) {
    SingletonPattern sp1 = SingletonPattern.newInstance();
    SingletonPattern sp2 = SingletonPattern.newInstance();
    System.out.println(sp1.r);
    System.out.println(sp2.r);
    System.out.println(sp1 == sp2);
  }
  */
  public static void main(String[] args){
    Frame f = new Frame();
    f.add(new Button("ok"));
    f.setSize(200,200);
    f.setVisible(true);
  }
}