设计模式之单例模式

//懒汉模式
public class Singleton {

    private static Singleton instance;

    /**
     * 私有化构造方法
     */
    private Singleton(){

    }

    public static Singleton getInstance(){
        if (instance == null){
            instance = new Singleton();
        }
        return instance;
    }

    public static void main(String[] args) {
        Singleton s1 = Singleton.getInstance();
        Singleton s2 = Singleton.getInstance();
        System.out.println(s1==s2);
    }
}

//饿汉模式
public class Singleton {

    private static Singleton instance = new Singleton();

    /**
     * 私有化构造方法
     */
    private Singleton(){

    }

    public static Singleton getInstance(){
        return instance;
    }

    public static void main(String[] args) {
        Singleton s1 = Singleton.getInstance();
        Singleton s2 = Singleton.getInstance();
        System.out.println(s1==s2);
    }
}