单态设计模式

 1 package com.cn;
 2
 3 public class Test {
 4     public static void main(String agrs[]){
 5         Person p1 = Person.getInstances();
 6         Person p2 = Person.getInstances();
 7         System.out.println(p1==p2);
 8     }
 9 }
10 class Person{
11     static Person person = new Person();
12     private Person(){
13
14     }
15     public static Person getInstances(){
16         return person;
17     }
18 }

打印结果为 ：true

保证了Person类在内存中只能被创建一个实例对象