Iterator <strings>不适用于HashTable Test

Question

我为哈希表编写的Iterator<String> elements()方法没有通过我给出的其中一个测试。这有什么问题？

public Iterator<String> elements(){
    Iterator<String> it = new Iterator<String>(){

        private int i = 0;

        @Override
        public boolean hasNext() {
            return i < hashTable.length && hashTable[i] != null;  //if i set this to always return true i get a null.pointer.exception.
                                                                  // then an error on line 115 which is the line for next().
        }

        @Override
        public String next() {
            i++;
            return hashTable[i].getKey();
        }

    };
    return it;
}

以下是测试：

    /** Test 8: Get iterator over all keys 
 * @throws MapException */
private static boolean test8() throws MapException {

    boolean result = true;
    String s;
    StringHashCode sHC = new StringHashCode();
    float maxLF = (float) 0.5;
    HashTableMap h = new HashTableMap(sHC,maxLF);
    try
    {
        for (int k = 0; k < 100; k++) 
        {
            s = (new Integer(k)).toString();           
            h.insert("R"+s+"C"+s);
        }

        for (int k = 10; k < 30; k++) 
        {
            s = (new Integer(k)).toString();
            h.remove("R"+s+"C"+s);
        }
    }
    catch(MapException e)
    {
        result = false;
    }
    Iterator<String> it = h.elements();
    int count = 0;

    while (it.hasNext()){
        count++;
        it.next();
    }
    if ( h.numberOfElements() != 80) {
        result = false;           
    }
    if ( count != 80) {
        result = false;           // if i comment out this line the test passes so i am assuming the iterator is the problem.                    
    }
    return result;
} 

我确信我的Iterator<String> elements()方法的代码是正确的，但我可能错过了一个简单的错误，因为我已经看了这么久。