Difference between ByteArrayOutputStream and BufferedOutputStream

Question

Both ByteArrayOutputStream and BufferedOutputStream do buffering by placing data in an array in memory. So my questions are

1. what a

Answer 1

Just look at the javadoc:

ByteArrayOutputStream:

This class implements an output stream in which the data is written into a byte array.

BufferedOutputStream:

The class implements a buffered output stream. By setting up such an output stream, an application can write bytes to the underlying output stream without necessarily causing a call to the underlying system for each byte written.

So, those are really two very different things:

• the first one you use when you know that you have some data that in the end you need as array of bytes
• the second one is just a wrapper around any other kind of output stream - which adds buffering.

That is all there is to this!

And if you want to experience a different behavior: create a buffered one that writes to a file, and an array one. Then just keep pushing bytes into each one. The array one will cause a memory problem at some point, the other one might not stop until all of your disk space is used up.