单例模式-饿汉与懒汉式

package Java0908;

public class TestSingleton {
    public static void main(String[] args) {
        Singleton instance = Singleton.getInstance();
        Singleton instance1 = Singleton.getInstance();

        System.out.println(instance == instance1);

        HungerSingleton singleton = HungerSingleton.getSingleton();
        HungerSingleton singleton1 = HungerSingleton.getSingleton();
        System.out.println(singleton == singleton1);


    }

}

//饿汉式
class Singleton {

    //2、在类的内部创建对象
    private static Singleton instance = new Singleton();

    //1、构造器私有化
    private Singleton() {

    }

    //3、提供公共的get方法
    public static Singleton getInstance() {
        return instance;
    }

}


//懒汉式
class HungerSingleton {

    //1、私有化构造器
    private HungerSingleton() {
    }

    //2、在类的内部创建对象
    private static HungerSingleton singleton = null;

    //3、提供公共的get方法
    public static HungerSingleton getSingleton() {
        if (singleton == null) {
            singleton = new HungerSingleton();
        }

        return singleton;

    }


}