public XPatternTokenizer(AttributeFactory factory,Pattern pattern,int group){
  super(factory);
  this.group=group;
  matcher=pattern.matcher("");
  if (group >= 0 && group > matcher.groupCount()) {
    throw new IllegalArgumentException("invalid group specified: pattern only has: " + matcher.groupCount() + " capturing groups");
  }
}

public XPatternTokenizer ( AttributeFactory factory , Pattern pattern , int group ) { super ( factory ) ; this . group = group ; matcher = pattern . matcher ( "" ) ; if ( group >= 0 && group > matcher . groupCount ( ) ) { throw new IllegalArgumentException ( "invalid group specified: pattern only has: " + matcher . groupCount ( ) + " capturing groups" ) ; } }
creates a new patterntokenizer returning tokens from group ( - 1 for split functionality )
