cityhubtopten.Top10Reducer.java Source code

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Here is the source code for cityhubtopten.Top10Reducer.java

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/*
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package cityhubtopten;

/**
 *
 * @author pranali
 */
import java.io.IOException;

import java.util.Iterator;

import java.util.TreeMap;

import java.util.Map.Entry;

import org.apache.hadoop.io.LongWritable;

import org.apache.hadoop.io.NullWritable;

import org.apache.hadoop.io.Text;

import org.apache.hadoop.mapreduce.Reducer;

import org.apache.hadoop.mapreduce.Reducer.Context;

public class Top10Reducer extends Reducer<NullWritable, Text, NullWritable, Text> {

    public static TreeMap<QualityOfLife, Text> ToRecordMap = new TreeMap<QualityOfLife, Text>();

    public void reduce(NullWritable key, Iterable<Text> values, Context context)
            throws IOException, InterruptedException {

        for (Text value : values) {

            String line = value.toString();

            if (line.length() > 0) {

                String[] tokens = line.split(",");

                //split the data and fetch salary

                double quality = Double.parseDouble(tokens[6]);

                //insert salary as key and entire row as value

                //tree map sort the records based on salary

                ToRecordMap.put(new QualityOfLife(quality), new Text(value));

            }

        }

        // If we have more than ten records, remove the one with the lowest sal

        // As this tree map is sorted in descending order, the user with

        // the lowest sal is the last key.

        Iterator<Entry<QualityOfLife, Text>> iter = ToRecordMap.entrySet().iterator();

        Entry<QualityOfLife, Text> entry = null;

        while (ToRecordMap.size() > 10) {

            entry = iter.next();

            iter.remove();

        }

        for (Text t : ToRecordMap.descendingMap().values()) {

            // Output our ten records to the file system with a null key

            context.write(NullWritable.get(), t);

        }

    }

}