java使用静态关键字实现单例模式

/**
 * 单例模式
 * @author xiongda
 * @date 2018年4月15日
 */
public class SingletonMode {
  private static SingletonMode single =null;
  public int number = 1;
  
  //将构造方法定义为私有
  private SingletonMode(){
    single=this;
  }
  public static SingletonMode getInstance(){
    if(single==null){
      single=new SingletonMode();
    }
    return single;
  }
}

public class Testit {

public static void main(String[] args) {
// TODO Auto-generated method stub
SingletonMode single =SingletonMode.getInstance();
System.out.println("single的number值："+single.number);

SingletonMode single2 =SingletonMode.getInstance();
single2.number=100;

SingletonMode single3 =SingletonMode.getInstance();
System.out.println("single3的number值："+single3.number);

System.out.println(single2==single3);
}

}