Word count in apache spark - Java Big Data

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Description

Word count in apache spark

Demo Code

/*// w  w  w . j av  a2  s. c o m
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
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package org.apache.spark.examples;

import scala.Tuple2;
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.FlatMapFunction;
import org.apache.spark.api.java.function.Function2;
import org.apache.spark.api.java.function.PairFunction;

import java.util.Arrays;
import java.util.List;
import java.util.regex.Pattern;

public final class JavaWordCount {
    private static final Pattern SPACE = Pattern.compile(" ");

    public static void main(String[] args) throws Exception {

        if (args.length < 1) {
            System.err.println("Usage: JavaWordCount <file>");
            System.exit(1);
        }

        SparkConf sparkConf = new SparkConf().setAppName("JavaWordCount");
        JavaSparkContext ctx = new JavaSparkContext(sparkConf);
        JavaRDD<String> lines = ctx.textFile(args[0], 1);

        JavaRDD<String> words = lines
                .flatMap(new FlatMapFunction<String, String>() {
                    @Override
                    public Iterable<String> call(String s) {
                        return Arrays.asList(SPACE.split(s));
                    }
                });

        JavaPairRDD<String, Integer> ones = words
                .mapToPair(new PairFunction<String, String, Integer>() {
                    @Override
                    public Tuple2<String, Integer> call(String s) {
                        return new Tuple2<String, Integer>(s, 1);
                    }
                });

        JavaPairRDD<String, Integer> counts = ones
                .reduceByKey(new Function2<Integer, Integer, Integer>() {
                    @Override
                    public Integer call(Integer i1, Integer i2) {
                        return i1 + i2;
                    }
                });

        List<Tuple2<String, Integer>> output = counts.collect();
        for (Tuple2<?, ?> tuple : output) {
            System.out.println(tuple._1() + ": " + tuple._2());
        }
        ctx.stop();
    }
}

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