Java中如何使某个类的对象唯一性，只能创建一个对象

方法一、

对象唯一性一般能想到工厂模式，单例模式，我们这里介绍一下举例懒汉法。

package com.liuyanzhao; class Student { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } private Student() { } private static Student s = new Student(); public static Student getInstance() { return s; } } public class Test { public static void main(String[] args) { Student s1 = Student.getInstance(); Student s2 = Student.getInstance(); s1.setName("Tom"); s2.setName("Jerry"); System.out.println(s1.getName());//Jerry System.out.println(s2.getName());//Jerry } }

新建的两个对象s1,s2其实是一个对象

方法二、

通过计数器统计来创建对象

package com.liuyanzhao; class Teacher { static int i=0; private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } private Teacher() { } public static Teacher newTeacher() { Teacher.i++; if(Teacher.i>1){ return null; } return new Teacher(); } } public class Test1 { public static void main(String[] args) { Teacher t = Teacher.newTeacher(); Teacher t1 = Teacher.newTeacher(); t.setName("Tom"); //t1.setName("Jerry"); System.out.println(t.getName()); //System.out.println(t1.getName()); } }

如上 只能创建一个对象，否则会报错。

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