Java-使用for循环反转单个LinkedList

Question

So the challenge right now is to try and take a LinkedList L and create a new LinkedList Reverse with the reverse of L. I need to accomplish this with a forloop. This is what I have so far:

public void ReverseL(Intco obj) {
    ListNode p = obj.c;
    ListNode RevL = c;
    int index = obj.get_howmany();
    if (obj.c != null) {
        while (this.get_howmany() != obj.get_howmany()) {
            p = obj.c;
            for (int i = index; i <= 0; i--) {
                p = p.link;
            }
            RevL = new ListNode(p.info, RevL);
            howmany++;
            index--;
        }
    }
    c = RevL;
}

Intco is the class I am working with. Howmany is the counter for how many integers are in the LinkedList (It is incremented by the insert method I made).

Let's say I add 4 integers to L, so L will contain: L -> 5 -> 12 -> 25 -> 15 -> null

howmany = 4 for L.

The forloop is going to go through L until it hits the 4th value, insert that 4th value to RevL. Go through L again, but hits 3rd value (25) now, then insert 3rd value to RevL.

The problem I am running into is my output is:

Reverse of L (Reverse): 
15
15
15
15

P: 
15
25
12
5

Just in case, here is the private class for the LinkedList:

private class ListNode {

    private int info;
    private ListNode link;

    public ListNode() {
        info = 0;
        link = null;
    }

    public ListNode(int i, ListNode next) {
        info = i;
        link = next;
    }
}

As you can see, it just repeats the last integer I have in the original linkedlist. Any help would be appreciated!

Answer 1

try change

for (int i = index; i <= 0; i--) {
            p = p.link;
        }

to

for (int i = index; i >= 0; i--) {
            p = p.link;
        }

Answer 2

You can implement a function named get(int index). Run the for loop through it. This get function will traverse the n, n-1, n-2, ... ,2,1.

Say you have a list of size 10. Loop goes like this:

for(int i=size; i>0; i-- {
   get(index);
}

Now how to implement get(int index). Since its a singly linked list. There is no way other than to traverse the list from 1st to the desired index.