Output stream over a StringBuilder [duplicate]

Question

I think this has been answered but I can't seem to find it.

I have an instance method which writes some contents to an output stream

writeTo(OutputStream){
     //class specific logic
}

I want it to get these contents into a StringBuilder. I can do this via a temporary file but that does not seem right. I want to do something like:

Stringbuilder sb = /* */;
OutputStream os = outForStringBuilder(sb);//not sure how to do this
instance.writeTo(os); //This should write the contents to Stringbuilder

Answer 1

Use a ByteArrayOutputStream and then call toString(charSet) - no need for a StringBuilder.