ByteBufferList skip bug

Created by: frank-fan

There is a bug about ByteBufferList#skip.

        ByteBufferList list = new ByteBufferList();
        list.add(ByteBuffer.wrap("12345".getBytes()));
        list.add(ByteBuffer.wrap("67890".getBytes()));

        list.skip(3);

        String content = list.readString();
        System.out.println(content);

Above code should output "4567890" instead of "1234567890".

I checked skip(int) method, redirecting to get(null, 0, length), and found out why.

public void get(byte[] bytes, int offset, int length) {
        if (remaining() < length)
            throw new IllegalArgumentException("length");

        int need = length;
        while (need > 0) {
            ByteBuffer b = mBuffers.peek();
            int read = Math.min(b.remaining(), need);
            if (bytes != null)
                b.get(bytes, offset, read);
            need -= read;
            offset += read;
            if (b.remaining() == 0) {
                ByteBuffer removed = mBuffers.remove();
                assert b == removed;
                reclaim(b);
            }
        }

        remaining -= length;
    }

When bytes is null, non effect will be took to ByteBuffer b, position should be still without change. I changed the code described as below, and fix this.

    public void get(byte[] bytes, int offset, int length) {
        if (remaining() < length)
            throw new IllegalArgumentException("length");

        int need = length;
        while (need > 0) {
            ByteBuffer b = mBuffers.peek();
            int read = Math.min(b.remaining(), need);
            if (bytes != null) {
                b.get(bytes, offset, read);
            } else {
                //when bytes is null, just skip data.
                b.position(b.position() + read);
            }

            need -= read;
            offset += read;
            if (b.remaining() == 0) {
                ByteBuffer removed = mBuffers.remove();
                assert b == removed;
                reclaim(b);
            }
        }

        remaining -= length;
    }