(单选) 以下 Java Spark 程序中mapValueRDD输出结果为()

public static void mapValues()
    {
        //创建SparkConf
        SparkConf conf = new SparkConf().setAppName("map").setMaster("local");
        //创建javaSparkContext
        JavaSparkContext sc = new JavaSparkContext(conf);

        JavaPairRDD<String,String> pairRDD = sc.parallelizePairs(Lists.newArrayList(new Tuple2<String, String>("a","1"),
                new Tuple2<String, String>("b","2"),new Tuple2<String, String>("a","3"),new Tuple2<String, String>("b","4")));

        JavaPairRDD<String,String> mapValueRDD=pairRDD.mapValues(new Function<String, String>() {
            public String call(String s) throws Exception {
                return  s+"test";
            }
        });
    }