如何在JavaPairRDD上使用max方法

Question

所以,我试图使用max in JavaPairRDD但无法使其工作.

JavaPairRDD<Integer, String> someRdd = (initialisation)

String maxValue = someRdd.max()  //not working

我的代码:http://ideone.com/0YXCJw

Answer 1

实现描述所需排序的比较器:

import scala.Tuple2;
import java.io.Serializable;

class DummyComparator implements 
      Comparator<Tuple2<Integer, String>>, Serializable {
   public int compare(Tuple2<Integer, String> x, Tuple2<Integer, String> y) {
        return -1;
    }
}

将其传递给max方法:

someRdd.max(new DummyComparator());