JAVA中的单例模式-＞饿汉式

一、步骤

1.构造器私有化=>防止直接new

// 步骤一、构造器私有化=>防止直接new
private GirlFriend(String name){System.out.println("构造器被调用");this.name = name;
}

2.类的内部创建对象

// 步骤二、类的内部创建对象（该对象是static）
private static GirlFriend girlFriend = new GirlFriend("鞠婧祎");

3.向外暴露一个静态的公共方法。getInstance

// 步骤三、向外暴露一个静态的公共方法。getInstancepublic static GirlFriend getInstance(){return girlFriend;}

二、代码实现

package SingleModel;
public class SingleModel01 {public static void main(String[] args) {// 通过方法可以获取对象GirlFriend girlFriend = GirlFriend.getInstance();System.out.println(girlFriend);GirlFriend girlFriend2 = GirlFriend.getInstance();System.out.println(girlFriend2);System.out.println(girlFriend == girlFriend2);}
}
class GirlFriend{private String name;// 步骤一、构造器私有化=>防止直接newprivate GirlFriend(String name){System.out.println("构造器被调用");this.name = name;}// 步骤二、类的内部创建对象（该对象是static）private static GirlFriend girlFriend = new GirlFriend("鞠婧祎");// 步骤三、向外暴露一个静态的公共方法。getInstancepublic static GirlFriend getInstance(){return girlFriend;}@Overridepublic String toString() {return "GirlFriend{" +"name='" + name + '\'' +'}';}
}