import java.util.ArrayList;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;
import java.util.TreeMap;
import java.lang.*;

import org.apache.commons.lang.StringUtils;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Reducer;

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

    ArrayList commonFriends = new ArrayList();
    ArrayList allcommonFriends = new ArrayList();

    for (Text word : values) {
        //java.lang.String[] friends = word.toString().split(" ");//convert string to string array
        //commonFriends.add(friends);
        allcommonFriends.add(word.toString());
    }


    //if(values.size()!=2) System.out.println("Error");

        StringTokenizer list1 = new StringTokenizer((String[]) allcommonFriends[0].toArray();
        StringTokenizer list2 = new StringTokenizer((String[]) allcommonFriends[1].toArray();

        while (list1.hasMoreTokens()) {
        friend1=list1.nextToken();
            while (list2.hasMoreTokens()) {
                friend2=list2.nextToken();
                if(friend1 == friend2) commonFriends(friend1);
                }
        }
        }
        Collection<String> allValues= commonFriends.values();
        java.lang.String entireText = StringUtils.join(allValues, ',');

        friendList.set(entireText);
        context.write(key, friendList);

}