"PipedWriter writer = new PipedWriter(System.in);" possible ????

[Peter Blatt]

I want to write something to System.in which in turn should be piped forward
to a buffered readLine() in another thread. In other words

BufferedWriter bw = new BufferedWriter(System.in);
bw.write("hello");

....

BufferedReader buf = new BufferedReader(new InputStreamReader(System.in));
String buf.readLine();

the variable "buf" should contain afterwards the String "hello";

Is such a construction possible ?
Do I have to declare

BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.in));

instead of the simple version above?

Regards
Peter