spark action之countbykey

java

 public class CountByKeyDemo {
     private static SparkConf conf = new SparkConf().setMaster("local").setAppName("countbykeydemo");
     private static JavaSparkContext jsc = new JavaSparkContext(conf);
     public static void main(String[] args) {
         List<Tuple2<String,Integer>> list = Arrays.asList(
                                             new Tuple2<String,Integer>("tele",100),
                                             new Tuple2<String,Integer>("tele",200),
                                             new Tuple2<String,Integer>("tele",300),
                                             new Tuple2<String,Integer>("yeye",50),
                                             new Tuple2<String,Integer>("yeye",10),
                                             new Tuple2<String,Integer>("yeye",70),
                                             new Tuple2<String,Integer>("wyc",10000)
                                              );

         JavaPairRDD<String, Integer> rdd = jsc.parallelizePairs(list);

         Map<String, Long> map = rdd.countByKey();
         map.entrySet().forEach(i-> System.out.println(i.getKey() + ":" + i.getValue()));

         jsc.close();
     }
 }

scala

 object CountByKeyDemo {
     def main(args: Array[String]): Unit = {
     val conf = new SparkConf().setMaster("local").setAppName("countdemo");
     val sc = new SparkContext(conf);

     val arr = Array(("class1","tele"),("class1","yeye"),("class2","wyc"));
     val rdd = sc.parallelize(arr,1);

     val result = rdd.countByKey();
     for((k,v) <- result) {
       println(k + ":" + v);
     }
   }
 }