代码
import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaRDD;
import org.apache.spark.api.java.JavaSparkContext;
import org.apache.spark.api.java.function.PairFunction;
import org.apache.spark.api.java.function.VoidFunction;
import scala.Tuple2;
import java.util.Iterator;
public class TestTN {
public static void main (String[] args){
SparkConf conf = new SparkConf();
conf.setMaster("local").setAppName("TestTN");
JavaSparkContext context = new JavaSparkContext(conf);
JavaRDD<String> lineRDD = context.textFile("./data/scores.txt");
JavaPairRDD<String, Integer> pairRDD = lineRDD.mapToPair(new PairFunction<String, String, Integer>() {
@Override
public Tuple2<String, Integer> call(String s) throws Exception {
String[] split = s.split(" ");
String topType = split[0];
Integer score = Integer.valueOf(split[1]);
return new Tuple2<String, Integer>(topType,score);
}
});
JavaPairRDD<String, Iterable<Integer> >groupRDD = pairRDD.groupByKey();
groupRDD.foreach(new VoidFunction<Tuple2<String, Iterable<Integer>>>() {
@Override
public void call(Tuple2<String, Iterable<Integer>> tuple2) throws Exception {
String className = tuple2._1;
Iterator<Integer> iterator = tuple2._2.iterator();
System.out.println(tuple2);
Integer[] top3 = new Integer[3];
while (iterator.hasNext()){
Integer next = iterator.next();
for (int i = 0; i < top3.length; i++) {
if (top3[i] == null){
top3[i] = next;
break;
}else if (next > top3[i]){
for (int j = top3.length-1; j>i;j--){
top3[j] = top3[j-1];
}
top3[i] = next;
break;
}
}
}
System.out.println("TopType : "+ className);
for (Integer score : top3){
System.out.println(score);
}
}
});
}
}
优化
Integer[] top3 = new Integer[3];
while (iterator.hasNext()){
Integer next = iterator.next();
for (int i = 0; i < top3.length; i++) {
if (top3[i] == null){
top3[i] = next;
break;
}else if (next > top3[i]){
for (int j = top3.length-1; j>i;j--){
top3[j] = top3[j-1];
}
top3[i] = next;
break;
}
