Wrapper Class --Decoration design pattern

當你想要使用某個class的功能, 卻想改善既有功能的不足, 可以使用decoration design pattern把原有類別包裹起來, 這樣既可擁有向下相容性,又可以增加新功能.

package designpattern;

public class WrapperClassDemo {
    
    public static void main(String [] args){
        CarV1 v1= new CarV1();
        CarV2 v2 = new CarV2(v1);
        v2.run();
        v2.run(1);
        v1.run();
    }

}

class CarV1{
    public void run(){
        System.out.println(" car v1 run");
    }
}

class CarV2{
    CarV1 c1;
    public CarV2(CarV1 c1){
        this.c1= c1;
    }
    
    public void run(int i){
        System.out.println(" car v2 run " + i);
    }
    
    public void run(){
        c1.run();
    }
}