java - How to use OutputStream to write to a String

I have a program in which I use a PrintStream object to write to a file. Is there a way to use something like a String Buffer or similar as the OutputStream for the object instead, so that I can use print to append to the String ?
I later want to be able to retrieve this String (obviously)

(ps. i wanna do this for testing purposes in my program)

Some info:

PrintStream ps = new PrintStream(myOutputStream);
...
ps.print(...);
...
ps.close();

I want to replace myOutputStream with some kind of String buffer which I can retrieve later and read.

As far as I know, in C++ we can do this as

stringstream ss;
ss << ...

How to do this in Java ?