Question

This case is a bit complex, I hope I will simplify it well.

My task starts when I receive PrintStream where I am supposed to output some data. However entire task is calculating + printing, and I can print when I am done with calculation. So this could be 2-pass task, but I hope for 1-pass.

In order to achieve this, I would like to create some output buffer, do calculation and printing (to buffer) and then print out from the buffer to the real output stream.

So far so good, the problem is I am unable to find appropriate class for buffering — BufferedOutputStream if I understand correctly, starts writing from the buffer when the buffer is full. I have to have much more strict control over it — not writing to real output until I exactly say so.

Question — is there any class appropriate for this task?

Answer 1

You could use ByteArrayOutputStream as your buffer. The byte array where this stream writes is enlarged automatically to hold everything you write.

When you are done generating output, just call the writeTo method to write the contents of the buffer to an output stream that writes to some actual device.

For further details see http://docs.oracle.com/javase/6/docs/api/java/io/ByteArrayOutputStream.html