@Override
    public String toString() {
        StringBuffer sb = new StringBuffer();
        sb.append("HashtableNaive {\n");
        for (int i = 0; i < currentSize; i++) {
            sb.append("  " + keys[i] + " => " + values[i] + "\n");
        }
        sb.append("}");
        return sb.toString();
    }