不兼容的类型:java.lang.Object 无法转换为 T
这是我的代码:
package datastructures;
import java.util.Iterator;
public class Stack<T>{
private class Node<T>{
T data;
Node next;
}
private int size;
private Node head;
private Node newNode(T data){
Node new_node = new Node();
new_node.data = data;
new_node.next = null;
return new_node;
}
public Stack(){
size = 0;
head = null;
}
public T pop() {
if(head == null)
return null;
T ret_val = head.data; //Error here
head = head.next;
this.size--;
return ret_val;
}
}
我在 pop 方法中得到错误，这里是错误:
I get the error in the pop method, here is the error:
Error: incompatible types : java.lang.Object cannot be converted to T
我不明白这个错误，我没有在代码中的任何地方使用 Object.
I don't understand this error, I'm not using Object anywhere in my code.
推荐答案
当你声明 Node 为时
When you declare Node as
private class Node<T>
您正在声明一个泛型类型，其中另一个 T 作为封闭类型中的 T.你隐藏了 T.所以，简而言之，就好像你将它声明为
you're declaring a generic type with another T as the T in the enclosing type. You're hiding T. So, in short, it's as if you were declaring it as
private class Node<E>
随便用
private class Node