Infinite loop when iterating through Linked List

Question

I am trying to count the number of time a particular integer occurs within my Linked List. However I am running into an infinite loop. I try to print variables to see where the code reaches but nothing prints. I was wondering if someone could be an extra pair of eyes for me.

My LinkedListNode class is simply:

public class LinkedListNode {
    int data;
    public LinkedListNode next;


    // constructor
    public LinkedListNode(int newData) {
        this.next = null;
        this.data = newData;
    }
}

My code:

public static int countInt(LinkedListNode head, int number) {
    int count = 0;

    while (head.next != null) {
        if (head.data == number) {
            count++;
            //System.out.println(count);
            head = head.next;
            //System.out.println(head.data);
        }
    }
    return count;
}

Maroun · Accepted Answer · 2014-01-07 11:51:49Z

5

You should move head to the next node even if the if doesn't satisfy.

answered Jan 7, 2014 at 11:51

Maroun

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5 Comments

Liondancer Over a year ago

did not see this thanks! it's late in the night for me!

Maroun Over a year ago

@Liondancer No problem, that's why there's a day and night in the world :) People in day help people in night ;)

Liondancer Over a year ago

I thought the world was flat... haha

Maroun Over a year ago

Well.. it is.

Liondancer Over a year ago

linked not found =/ but im sure it was funny haha

Balduz · Accepted Answer · 2014-01-07 11:52:12Z

3

You only move to the next node when the current node is equal to the number you send to countInt.

answered Jan 7, 2014 at 11:52

Balduz

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Comments

Vu Doan · Accepted Answer · 2018-08-15 15:54:23Z

1

Moving head = head.next out of the while loop will help with the infinite loop, but you would want to check the head for null, not head.next, so the while loop will check the value of the last element

public static int countInt(LinkedListNode head, int number) {
    int count = 0;

    while (head != null) {
        if (head.data == number) {
            count++;
            //System.out.println(count);

            //System.out.println(head.data);
        }
        head = head.next;
    }
    return count;
}

answered Aug 15, 2018 at 15:54

Vu Doan

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