java - 类型不匹配 : cannot convert from "sth" to "sth"

Question

我有这段代码:

public class ListCollection<T> implements Iterable<T> {

    private int size;
    private ListNode<T> first;
    private ListNode<T> last;
    ...

private class ListNode<E> {
    private ListNode<E> next;
    private ListNode<E> previous;
    private E value;

    public ListNode() {
        super();
    }
}
private class ListIterator<T> implements Iterator<T> {

        ListNode<T> next, previous;

        public ListIterator() {
            next = first;
        }

我想初始化迭代器。在 next = first 行中，我收到错误消息。

Type mismatch: cannot convert from ListCollection.ListNode to ListCollection.ListNode

为什么？我该如何纠正这个问题？

Answer 1

改变

private class ListIterator<T> implements Iterator<T>

到

private class ListIterator implements Iterator<T>

否则ListIterator<T>使用的类型参数T不会与 ListCollection<T> 中声明的类型参数 T 相同.