class Singleton{
    private static Singleton instance;//內部實例化對象
    public static Singleton getInstance(){
        if(instance == null){
            instance =  new Singleton();
        }
        return instance;
    }
    private Singleton(){} //構造方法私有化
    public void print(){
        System.out.println(
 
"hellow word");
    }
     
    
}

public class Lxd{
    public static void main(String[] args) {
        Singleton s = null; //聲明對象
        s = Singleton.getInstance(); //直接訪問Static屬性
        s.print(); //使用方法
    }
}

class Singleton{
    private static final Singleton instance = new Singleton();//內部實例化對象
 

    public static Singleton getInstance(){  //調用實例對象的方法
        return instance;
    }
    private Singleton(){} //構造方法私有化
    public void print(){
        System.out.print("hello");
    }
}

public class LxdT {
    public static void main(String[] args) {
        Singleton s = Singleton.getInstance();  //
 
類名.方法名調用
        s.print();  //使用方法
    
    }
    
}

定義一個單例設計Singleton