@Override
    public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
        final int num = in.readInt();
        mapTable = new Entry[num];
        listTable = new Entry[num];
        threshold = (int) (num * LOAD_FACTOR);
        final int size = in.readInt();
        for (int i = 0; i < size; i++) {
            final K key = (K) in.readObject();
            final V value = (V) in.readObject();