java 写一个单例设计程序，打印出该对象的地址

class Test{
    public static void main(String[] args) {
        singleton s1=singleton.getinstance();
        singleton s2=singleton.getinstance();
        System.out.println(s1);
        System.out.println(s2);

    }
}
class singleton{

 private final static singleton per=new singleton();
    private singleton (){};
    public  static singleton getinstance(){
        return per;
    }