我有一个mapreduce程序如下

import java.io.IOException;
import java.util.Iterator;
import java.util.StringTokenizer;

import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.FileInputFormat;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobClient;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.KeyValueTextInputFormat;
import org.apache.hadoop.mapred.MapReduceBase;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.OutputCollector;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mapred.Reporter;
import org.apache.hadoop.mapred.TextOutputFormat;

public class Sample {

public static class SampleMapper extends MapReduceBase implements
        Mapper<Text, Text, Text, Text> {

    private Text word = new Text();

    @Override
    public void map(Text key, Text value,
            OutputCollector<Text, Text> output, Reporter reporter)
            throws IOException {
        StringTokenizer itr = new StringTokenizer(value.toString(),",");
        while (itr.hasMoreTokens()) {
            word.set(itr.nextToken());
            output.collect(key, word);
        }
    }
}

public static class SampleReducer extends MapReduceBase implements
        Reducer<Text, Text, Text, Text> {

    private Text result = new Text();

    @Override
    public void reduce(Text key, Iterator<Text> values,
            OutputCollector<Text, Text> output, Reporter reporter)
            throws IOException {

        StringBuffer aggregation = new StringBuffer();
        while (values.hasNext()) {
            aggregation.append("|" + values.next().toString());
        }
        result.set(aggregation.toString());
        output.collect(key, result);
    }

}

public static void main(String args[]) throws IOException {
    JobConf conf = new JobConf(Sample.class);
    conf.setJobName("Sample");

    conf.setMapperClass(SampleMapper.class);
    conf.setReducerClass(SampleReducer.class);
    conf.setOutputKeyClass(Text.class);
    conf.setOutputValueClass(Text.class);
    conf.setInputFormat(KeyValueTextInputFormat.class);
    conf.setOutputFormat(TextOutputFormat.class);
    FileInputFormat.setInputPaths(conf, new Path(args[0]));
    FileOutputFormat.setOutputPath(conf, new Path(args[1]));

    JobClient.runJob(conf);

}
}

我已经做了jar，我一直在努力得到输出。但是正在创建的输出文件是空的。
我正在使用以下命令运行作业

hadoop jar mapreduce.jar Sample /tmp/input tmp/output

jar是我打包的jar，我的输入文件如下

1 a,b,c
2 e,f
1 x,y,z
2 g

预期产量

1 a|b|c|x|y|z
2 e|f|g