案例三

public class Top3 {

public static void main(String[] args) {

​​SparkConf conf = new SparkConf().setAppName("Top3").setMaster("local");

​​JavaSparkContext sc= new JavaSparkContext(conf);
JavaRDD<String> lines = sc.textFile("C:/Users/zhang/Desktop/a.txt");
JavaPairRDD<Integer, String> pairs =​lines.mapToPair(new PairFunction<String, Integer, String>() {

​​@Override
​​public Tuple2<Integer, String> call(String t) throws Exception {
​​​// TODO Auto-generated method stub
​​​return new Tuple2<Integer, String>(Integer.valueOf(t), t);
​​}
​});

JavaPairRDD<Integer, String> sortedPairs = pairs.sortByKey(false);
​JavaRDD<Integer> sortedNumbers = sortedPairs.map(new Function<Tuple2<Integer,String>, Integer>() {

 @Override
public Integer call(Tuple2<Integer, String> v1) throws Exception {
​​​// TODO Auto-generated method stub
​​​return v1._1;
​​}
​});

​List<Integer> sortedNumberList = sortedNumbers.take(3);
​for(Integer num : sortedNumberList){

System.out.println(num);
​}

​sc.close();
}
}

object Top3 {
def main(args: Array[String]){
  val conf = new SparkConf().setAppName("Top3").setMaster("local")
  val sc = new SparkContext(conf)
 
  val lines = sc.textFile("C:/Users/zhang/Desktop/a.txt", 1)
  val pairs = lines.map { line => (line.toInt,line) }
  val sortedPairs = pairs.sortByKey(false)      
  val sortedNumbers = sortedPairs.map(sortedPair => sortedPair._1)
  val top3Number = sortedNumbers.take(3)
  for(num <- top3Number){
    println(num)
  }
 
}
}