Operator_countByKey

package com.bjsxt.spark.actions;

import java.util.Arrays;
import java.util.Map;
import java.util.Map.Entry;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.JavaPairRDD;
import org.apache.spark.api.java.JavaSparkContext;

import scala.Tuple2;
/**
* countByKey
*
* 作用到K,V格式的RDD上，根据Key计数相同Key的数据集元素。返回一个Map<K,Object>
* @author root
*
*/
public class Operator_countByKey {
public static void main(String[] args) {
SparkConf conf = new SparkConf();
conf.setMaster("local").setAppName("countByKey");
JavaSparkContext sc = new JavaSparkContext(conf);
JavaPairRDD<Integer, String> parallelizePairs = sc.parallelizePairs(Arrays.asList(
new Tuple2<Integer,String>(1,"a"),
new Tuple2<Integer,String>(2,"b"),
new Tuple2<Integer,String>(3,"c"),
new Tuple2<Integer,String>(4,"d"),
new Tuple2<Integer,String>(4,"e")
));

Map<Integer, Object> countByKey = parallelizePairs.countByKey();
for(Entry<Integer,Object> entry : countByKey.entrySet()){
System.out.println("key:"+entry.getKey()+"value:"+entry.getValue());
}


}
}