day4 单列模式之饿汉式

public class Sing {

    public static  Sing instance = new Sing();

    
    private Sing(){

    }
}




public class SingTest {
    public static void main(String[] args) {
        Sing s1 = Sing.instance;
        Sing s2 = Sing.instance;
        Sing s3 = Sing.instance;

        System.out.println(s1);
        System.out.println(s2);
        System.out.println(s3);
        System.out.println(s3==s1);


    }
}