java 简单的单例模式

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package com.lesson3_1类和对象;

//懒汉式单例模式
public class Singleton_2 {
   //私有化构造方法使其不能被初始化
   private Singleton_2() {
   }
   //属性
   private static Singleton_2 instance;

   //实例化方法 synchronized线程同步
   public synchronized static Singleton_2 getIntance(){
       if(instance == null){
           instance = new Singleton_2();
       }
       return instance;
   }
}

package com.lesson3_1类和对象;

//饿汉式单例模式
public class Singleton_1 {
   //私有化构造方法使其不能被初始化
   private Singleton_1() {
   }
   //属性
   private static Singleton_1 instance = new Singleton_1();

   //实例化方法
   public static Singleton_1 getInstance(){
       return instance;
   }
   String name;//测试属性

}

package com.lesson3_1类和对象;

class C1{
   String name;
}

//测试类
public class SingletonTest {

   public static void main(String[] args) {
       /** 普通对象 **/
       C1 a = new C1();
       C1 b = new C1();

       System.out.println(a == b);
       System.out.println(a.equals(b));

       /** 单例 **/
       Singleton_1 s1 = Singleton_1.getInstance();
       Singleton_1 s2 = Singleton_1.getInstance();

       System.out.println(s1 == s2);
       System.out.println(s1.equals(s2));

       /** 懒汉式 **/
       Singleton_2 ss1 = Singleton_2.getIntance();
       Singleton_2 ss2 = Singleton_2.getIntance();

       System.out.println(ss1 == ss2);
       System.out.println(ss1.equals(ss2));

       //---------------------------------
       a.name = "张三";
       System.out.println(b.name);

       s1.name = "王二麻子";
       System.out.println(s2.name);
   }
}//测试截图

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