public < R > MapOperator < T , R > map ( MapFunction < T , R > mapper ) { if ( mapper == null ) { throw new NullPointerException ( "Map function must not be null." ) ; } String callLocation = Utils . getCallLocationName ( ) ; TypeInformation < R > resultType = TypeExtractor . getMapReturnTypes ( mapper , getType ( ) , callLocation , true ) ; return new MapOperator <> ( this , resultType , clean ( mapper ) , callLocation ) ; }
Applies a Map transformation on this DataSet .