get an outputstream string

what's best proceed summons cost an java.io.outputstream twine java?

say i have method:

  writetostream(object o, outputstream out)

which writes certain information vigilant given stream. however, i wish cost twine simply possible.

i'm deliberation minute category (untested):

class stringoutputstream extends outputstream {

  stringbuilder mbuf;

  open vacant write(int byte) throws ioexception {
    mbuf.append((char) byte);
  }

  open twine getstring() {
    relapse mbuf.tostring();
  }
}

but there improved way? i wholly wish run test!