private void readFromSourceInput(){
  if (sourceInput.isDone()) {
    close();
  }
 else {
    sourceInput.read(thisBuffer);
  }
}

private void readFromSourceInput ( ) { if ( sourceInput . isDone ( ) ) { close ( ) ; } else { sourceInput . read ( thisBuffer ) ; } }
pre - condition : sourceinput ! = null , thisbuffer . getsamplecount ( ) > 0
