class Singleton{        private static final Singleton INSTANCE = new Singleton(); //在类内部封装对象        public static Singleton getInstance(){        return INSTANCE;    }        private Singleton(){ //构造方法私有化            }        public void print(){        System.out.println("HelloWorld!");            }}public class helloworld {    public static void main(String[] args) {        Singleton inst = null;        inst = Singleton.getInstance();        inst.print();            }}