Question

我写了一个类A，如下面的

class A <E> {  // class A has objects of E

    int x;

    private B<T> next // a object of inner class

    class B<T> { 
        // an inner class having objects of type T

        T[] elements = (T[]) Object[x];
        // has other stuff including many objects  
    }

 public A<E> func ( B<E> val ){
  Here I want to clone the value of val so that I can do different operations on other   
 }

问题出现了，我想写B<E> Temp = B<E>Value.clone()，其中Value在代码中定义。

但它说克隆不可见。

我该怎么做才能做到这一点......

非常感谢...

Answer 1

clone（）受到保护，因此您只需要在B中重新定义以执行您需要的任何操作。

Answer 2

最好不要使用clone()，而是在B上实现复制构造函数：

 class B extends A { 
    // an inner class having objects of type 
    List<String> strings = ArrayList<String>();

    public B(B that) {
       super(that); // call the superclass's copy constructor
       this.strings = new ArrayList<String>();
       this.strings.add(that.strings);
    }

    // ...
}

然后致电

public C func ( B val ){
   B clone = new B(val);
}

（删除了泛型内容以限制复制构造函数本身的演示）

Answer 3

以下是Peter的答案示例（未经测试，可能需要一些语法检查）：

class A <E> {  // class A has objects of E

    int x;

    private B<T> next // a object of inner class

    class B<T> implements Cloneable {
        public B<T> clone() {
           try {
              B<T> klon = (B<T>) super.clone();
              // TODO: maybe clone the array too?
              return klon;
           }
           catch(CloneNotSupportedException) {
              // should not occur
              throw new Error("programmer is stupid");
           }
        }
        // an inner class having objects of type T

        T[] elements = (T[]) Object[x];
        // has other stuff including many objects  
    }

 public A<E> func ( B<E> val ){
     B<E> clone = val.clone();
     // more code
 }

克隆内部类的对象

3 个答案: