mapreduce WordCount example using outputcollector - hadoop

Question

I'm trying to run basic wordcount mapreduce example using outputcollector , but im getting exceptions.
INFO mapreduce.Job: Job job_local1048833344_0001 failed with state FAILED due to: NA
java.lang.Exception: java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, received org.apache.hadoop.io.LongWritable ...
Here is the code I'm trying to run:
import java.io.*;
import java.util.StringTokenizer;
import java.util.Iterator;
import org.apache.hadoop.io.*;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.io.ObjectWritable;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.util.GenericOptionsParser;
public class WordCountOutputCollector {
public static class WordCountOutputCollectorMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable key, Text value, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
String line = value.toString();
StringTokenizer tokenizer = new StringTokenizer(line);
while (tokenizer.hasMoreTokens()) {
word.set(tokenizer.nextToken());
output.collect(word, one);
}
}
}
public static class WordCountOutputCollectorReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
public void reduce(Text key, Iterator<IntWritable> values, OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException {
int sum = 0;
while (values.hasNext()) {
sum += values.next().get();
}
output.collect(key, new IntWritable(sum));
}
}
public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();
if (otherArgs.length != 2) {
System.err.println("Usage: wordcount <in> <out>");
System.exit(2);
}
Job job = new Job(conf, "word count outputcollector");
job.setJarByClass(WordCountOutputCollector.class);
job.setMapperClass(WordCountOutputCollectorMapper.class);
job.setCombinerClass(WordCountOutputCollectorReducer.class);
job.setReducerClass(WordCountOutputCollectorReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
//conf.setInputFormat(TextInputFormat.class);
//conf.setOutputFormat(TextOutputFormat.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
//JobClient.runJob(conf);
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}

Answer 1

Try This : hadoop-wordcount
import java.io.IOException;
import java.io.PrintStream;
import java.util.StringTokenizer;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Mapper.Context;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.Reducer.Context;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.GenericOptionsParser;
public class WordCount
{
public static class Map
extends Mapper<LongWritable, Text, Text, IntWritable>
{
private static final IntWritable one = new IntWritable(1);
private Text word = new Text();
public void map(LongWritable paramLongWritable, Text paramText, Mapper<LongWritable, Text, Text, IntWritable>.Context paramMapper)
throws IOException, InterruptedException
{
StringTokenizer localStringTokenizer = new StringTokenizer(paramText.toString());
while (localStringTokenizer.hasMoreTokens())
{
this.word.set(localStringTokenizer.nextToken());
paramMapper.write(this.word, one);
}
}
}
public static class Reduce
extends Reducer<Text, IntWritable, Text, IntWritable>
{
private IntWritable result = new IntWritable();
public void reduce(Text paramText, Iterable<IntWritable> paramIterable, Reducer<Text, IntWritable, Text, IntWritable>.Context paramReducer)
throws IOException, InterruptedException
{
int i = 0;
for (IntWritable localIntWritable : paramIterable) {
i += localIntWritable.get();
}
this.result.set(i);
paramReducer.write(paramText, this.result);
}
}
public static void main(String[] paramArrayOfString)
throws Exception
{
Configuration localConfiguration = new Configuration();
String[] arrayOfString = new GenericOptionsParser(localConfiguration, paramArrayOfString).getRemainingArgs();
if (arrayOfString.length != 2)
{
System.err.println("Usage: WordCount <in> <out>");
System.exit(2);
}
Job localJob = new Job(localConfiguration, "wordcount");
localJob.setJarByClass(WordCount.class);
localJob.setMapperClass(WordCount.Map.class);
localJob.setReducerClass(WordCount.Reduce.class);
localJob.setCombinerClass(WordCount.Reduce.class);
localJob.setOutputKeyClass(Text.class);
localJob.setOutputValueClass(IntWritable.class);
FileInputFormat.addInputPath(localJob, new Path(arrayOfString[0]));
FileOutputFormat.setOutputPath(localJob, new Path(arrayOfString[1]));
System.exit(localJob.waitForCompletion(true) ? 0 : 1);
}
}

Answer 2

I think it's mainly because the map output has not been converted into Text.
Try to uncomment the code below:
conf.setInputFormat(TextInputFormat.class);
conf.setOutputFormat(TextOutputFormat.class);
JobClient.runJob(conf);