Concurrent read/write buffer byte[] in java

Question

I'm new to Java and I want to implement a buffer of byte[] which one thread can write into, and another thread can read from.
It sounds like it should have already been implemented in java , but I spent hours trying to find/understand several number of classes, and I didn't understand if it does what I want, and how to use it.
I saw BufferedInputStream , ByteBuffer , ByteChannel , BlockingQueue ...

Can someone please point to a more specific direction? I use SDK 1.6

Answer 1

If you're looking to simply stream bytes from one thread to the other, I suggest you use PipedInputStream and PipedOutputStream . Though note that it's likely you're in this position where you need a solution such as this because of a design fault.

Here is how you would do such thing, for instance:

PipedOutputStream out = new PipedOutputStream();
PipedInputStream in = new PipedInputStream(out);
new YourReadingThread(in).start();
new YourWritingThread(out).start();

Then anything you write to out will be available for reading through in .

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If you're looking for a solution to make a thread safe ByteBuffer, I would suggest you use a ReentrantReadWriteLock :

ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
ByteBuffer buffer = ByteBuffer.allocate(n);

// Reading thread:
lock.readLock().lock();
buffer.get(i);
lock.readLock().unlock();

// Writing thread:
lock.writeLock().lock();
buffer.put(b,i);
lock.writeLock().unlock();

Answer 2

Sorry, ByteBuffer wasn't good for me cause it involves playing with the position of the buffer.
I realized all I really needed was a simple pipe (I don't know how could I forget about pipes).

I used an example from here :

PipedOutputStream output = new PipedOutputStream();
PipedInputStream input = new PipedInputStream(output);