Question

I would like to ask for opinions/advices regarding a a part of my algorithm.

ByteBuffer bb = ByteBuffer.allocate(8);
bb.putLong(rs.getLong(index));//retrieve long from db (unsigned INT)
byte[] tmp = new byte[4];
bb.position(4);
bb.get(tmp);
(Inet4Address) InetAddress.getByAddress(tmp);

vs.

ByteBuffer bb = ByteBuffer.allocate(4);
bb.putInt((int) rs.getLong(index));//retrieve long from db (unsigned INT)
bb.flip();
byte[] tmp = new byte[4];
bb.get(tmp);
(Inet4Address) InetAddress.getByAddress(tmp);

Basically I would like to know whether there is a performance difference in casting or is it better to use bigger ByteBuffer.

Thanks, regards,

Marek

Answer 1

Basically I would like to know whether there is a performance difference in casting or is it better to use bigger ByteBuffer.

Casting is “cheap” especially compared to allocating new ByteBuffers and calling a few methods.

I’m not entirely sure what you’re trying to do, but perhaps a simple shift-right would do the trick? For instance this snippet of code:

long l = rs.getLong(index);
InetAddress.getByAddress(new byte[] { (byte) ((l & 0xFF000000) >> 24),
                                      (byte) ((l & 0x00FF0000) >> 16),
                                      (byte) ((l & 0x0000FF00) >>  8),
                                      (byte) ((l & 0x000000FF) >>  0)});