Fast erase (not clear) a ByteBuffer in Java

java bytebuffer erase
asksw0rder picture asksw0rder · Jun 25, 2012 · Viewed 10.8k times · Source

I am trying to "clean up" a ByteBuffer to be all zero bytes (all 0x00). I tried to loop over all positions in the buffer and set them to 0x00, but the efficiency is bad. Is there any better way to quickly clear a ByteBuffer - similar to what BitSet.clear() does?

Please note that ByteBuffer.clear() is not an appropriate solution for me in this scenario--I have to erase all the data inside of the buffer, and not just reset the pointer to the beginning.

Any hints?

Edit: the ByteBuffer is used as a part of the hash table, and it maintains the references of the hash table entries. Every time when the hash table needs to be flushed, I have to reset the hash table entries for later hash table insertion. Since the hash table is accessed in a random-fashion, I cannot simply clear() the state of the byte buffer.

Answer

DNA picture DNA · Jun 25, 2012

Have you tried using one of the ByteBuffer.put(byte[]) or ByteBuffer.put(ByteBuffer) methods to write multiple zeros in one go? You could then iterate over the buffer in chunks of 100 or 1000 bytes, or whatever, using an array or buffer pre-filled with zeros.

Downside: this is an optional operation, so not all implementations of ByteBuffer are required to provide it...

Related questions

converting Java bitmap to byte array

Bitmap bmp = intent.getExtras().get("data"); int size = bmp.getRowBytes() * bmp.getHeight(); ByteBuffer b = ByteBuffer.allocate(size); bmp.copyPixelsToBuffer(b); byte[] bytes = new byte[size]; try { b.get(bytes, 0, bytes.length); } catch (BufferUnderflowException e) { // always happens } // do something with byte[] …

Read More
What is the use of ByteBuffer in Java?

What are example applications for a ByteBuffer in Java? Please list any example scenarios where this is used. Thank you!

Read More
Java: Converting String to and from ByteBuffer and associated problems

I am using Java NIO for my socket connections, and my protocol is text based, so I need to be able to convert Strings to ByteBuffers before writing them to the SocketChannel, and convert the incoming ByteBuffers back to Strings. …

Read More