接口引用

Question

我不知道如何解決這個問題。這裏是我的代碼：

public interface Stuff { 
    public String description(); 
    public double weight(); 
} 

class Bag implements Stuff { 
    public String description() { 
     return "bag of"; 
    } 
    public double weight() { 
     return 10.50; 
    } 
} 

class StuffWrapper implements Stuff { 

    Stuff item; 

    public StuffWrapper(Stuff item) { 
     this.item = item; 
    } 

    public String description() { 
     return item.description(); 
    } 

    public double weight() { 
     return item.weight(); 
    } 
} 

class Material extends StuffWrapper { 

    String material; 
    double weight; 

    public Material(Stuff item, String material, double weight) { 
     super(item); 
     this.material = material; 
     this.weight = weight; 
    } 

    public String description() { 
     return item.description() + " :" + material+ ":"; 
    } 

    public double weight() { 
     return item.weight() + weight; 
    } 
} 

，然後我有這樣的：

Stuff icStuff = new Bag(); 
icStuff = new Material(icStuff, "leather", 10.30); 
icStuff = new Material(icStuff, "plastic", 20.50); 
System.out.println(icStuff.description() + Double.toString(icStuff.weight())); 

其輸出

bag of :leather: :plastic:41.3 

做所有的，如果我想icStuff不再引用此之後：

icStuff = new Material(icStuff, "plastic", 20.50); 

我應該怎麼做？

Answer 1

將其分配給別的東西，或爲空，或任何你想讓它引用

icStuff = null; 
icStuff = Somethingelse;