public String readUntil(char c){
  int ix=data.indexOf(c,pos);
  if (ix == -1)   throw new RuntimeException("readUntil did not find character '" + c + "'");
  return readN(data.indexOf(c,pos) - pos);
}

public String readUntil ( char c ) { int ix = data . indexOf ( c , pos ) ; if ( ix == - 1 ) throw new RuntimeException ( "readUntil did not find character '" + c + "'" ) ; return readN ( data . indexOf ( c , pos ) - pos ) ; }
read until the next char is c , and return the string .
