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();