单例模式

package com.bh.test;

public class Person {
    //(2)
    //private static Person person;
    //将person变量定义成静态变量，因为getInstance()为静态方法只能调用静态变量
    private static Person person = new Person();
    private String name;
    private Person(){}
 //将构造器私有化后只能本类调用，所以通过一个public方法来调用构造器实现创建对象，别的类只需要调用这个方法就行，又因为别的类不能创建对象所以方法变成static修饰的静态，只需要类名.方法就行
    public static Person getInstance(){
       /*(2) 
       Person p = new Person();
        if (person == null){
            person = new Person();
        }*/
        return person;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

package com.bh.test;

public class Test {
    public static void main(String[] args) {
        Person p1 = Person.getInstance();
        Person p2 = Person.getInstance();
        Person p3 = Person.getInstance();

        System.out.println(p1.getName());
        System.out.println(p2.getName());
        System.out.println(p3.getName());
    }
}