Question

when scanning a file for words and using the built-in hashset class from the API, my word count returns 349 (which is what it’s supposed to be)

Using my home-made hashset class, I get 235… so something in my add() method must be wrong, but I can’t understand what it is.

thanks for any help!

public class HashWordSet implements WordSet {

private int size = 0;
private Node[] buckets = new Node[8];

public Iterator<Word> iterator() {
    return new WordIterator();
}

//Add word if not already added
public void add(Word word) {
    int key = getBucketNumber(word);
    Node node = buckets[key];
    while (node != null) {
        if (node.value.equals(word))
            return;
        else
            node = node.next;
    }
    node = new Node(word);
    buckets[key] = node;
    size++;
    if (size == buckets.length) rehash();
}

private int getBucketNumber(Word word) {
    int hc = word.hashCode();
    if (hc < 0) hc = -hc;
    return hc % buckets.length;
}

Answer 1

node = new Node(word);
buckets[key] = node;

If there are any nodes already in the bucket you have just thrown them away. Try something like:

node = new Node(word);
node.next = buckets[key];
buckets[key] = node;