单例模式之饿汉式

class HungryMan {
    //设计模式之饿汉式，因为是static修饰的，所以是类成员，
    //在类被加载时就初始化对象了，不存在线程安全问题
    static private HungryMan hungryMan = new HungryMan();
    static HungryMan getHungryMan() {
        return hungryMan;
    }
}

public class Demo2 {
    public static void main(String[] args) {
        HungryMan hungryMan1 = HungryMan.getHungryMan();
        HungryMan hungryMan2 = HungryMan.getHungryMan();
        System.out.println(hungryMan1 == hungryMan2);
    }
}

输出：
true