java反转双链接列表的整个列表的顺序

Question

我在读java实现中的队列。我想执行以下任务：

public class DoublyLinkedList
{
    private Node first; // the first Node in the list
    private Node last; // the last Node in the list  

    private class Node
    {
        private Point p;
        private Node prev; // the previous Node
        private Node next; // the next Node
    }  

    public void reverse()
    {
        // your code
    }
}

我喜欢这样：

public void reverse() { // that reverses the order of the entire list
    if (first == null && last == null) {
         throw new RuntimeException(); 
    }  

    Node current = first;
    while (current!=null) {
        current.next= current.next.prev;
        current.prev=current.prev.next;
        current=current.next;
    }  
}

我做得对吗？ 谢谢

Answer 1

不，不是current.next = current.next.prev像current.next = current，而current.prev = current.prev.next像current.prev = current。请附加调试器并按照代码查找错误和正确的解决方案。我们不会在这里给你做作业

Answer 2

您不会更改代码中的第一个和最后一个指针。如果列表为空，为什么要抛出异常

我想我会这样做：

public void reverse()
{
    Node current = first;
    while (current != null) {
        Node next = current.next;
        current.next = current.prev;
        current.prev = next;
        current = next;
    }
    Node temp = first;
    first = last;
    last = temp;
}