If you want to make your first example faster

FileChannel inChannel = new FileInputStream(fileName).getChannel();ByteBuffer buffer = ByteBuffer.allocateDirect(CAPACITY);while(inChannel.read(buffer) > 0)    buffer.clear(); // do something with the data and clear/compact it.inChannel.close();

If you want it to be even faster.

FileChannel inChannel = new RandomAccessFile(fileName, "r").getChannel();MappedByteBuffer buffer = inChannel.map(FileChannel.MapMode.READ_ONLY, 0, inChannel.size());// access the buffer as you wish.inChannel.close();