hadoop程序中的类型不匹配错误

Question

import java.io.IOException;
import java.util.*;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
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;
public class CommonFriends {
        public static class TokenizerMapper
                extends Mapper<Object, Text, Text, IntWritable>{
                private IntWritable friend = new IntWritable();
                private Text friends = new Text();
                public void map(Object key, Text value, Context context )     throws IOException, InterruptedException {
                        StringTokenizer itr = new     StringTokenizer(value.toString(),"\n");
                    while (itr.hasMoreTokens()) {
                            String[] line = itr.nextToken().split(" ");
                            if(line.length > 2 ){
                                    int person = Integer.parseInt(line[0]);
                                    for(int i=1; i<line.length;i++){
                                            int ifriend = Integer.parseInt(line[i]);
                                            friends.set((person < ifriend ? person+"-"+ifriend : ifriend+"-"+person));
                                            for(int j=1; j< line.length; j++ ){
                                                    if( i != j ){
                                                            friend.set(Integer.parseInt(line[j]));
                                                            context.write(friends, friend);
                                                    }
                                            }
                                    }
                            }
                    }
            }
    }

    public static class IntSumReducer extends Reducer<Text,IntWritable,Text,Text> {
            private Text result = new Text();
            public void reduce(Text key, Iterable<IntWritable> values, Context context)
                    throws IOException, InterruptedException {
                    HashSet<IntWritable> duplicates = new HashSet();
                    ArrayList<Integer> tmp = new ArrayList();
                    for (IntWritable val : values) {
                            if(duplicates.contains(val))
                                    tmp.add(val.get());
                            else
                                    duplicates.add(val);
                    }
                    result.set(tmp.toString());
                    context.write(key, result);
            }
    }

    public static void main(String[] args) throws Exception {
            Configuration conf = new Configuration();
            Job job = Job.getInstance(conf, "Common Friends");
            job.setJarByClass(CommonFriends.class);
            job.setMapperClass(TokenizerMapper.class);
            job.setCombinerClass(IntSumReducer.class);
            job.setReducerClass(IntSumReducer.class);
            job.setMapOutputKeyClass(Text.class);
            job.setMapOutputValueClass(IntWritable.class);
            job.setOutputKeyClass(Text.class);
            job.setOutputValueClass(Text.class);
            FileInputFormat.addInputPath(job, new Path(args[0]));
            FileOutputFormat.setOutputPath(job, new Path(args[1]));
            System.exit(job.waitForCompletion(true) ? 0 : 1);
    }
}

错误：java.io.ioException：错误值类：类org.apache.hadoop.io.text不是类org.apache.hadoop.mapred.ifile$writer.append(ifile.java:194)在org.apache.hadoop.mapred.task$combineoutputCollector.collect(task.java:1350)在org.apache.hadoop.mapred.task$newcombinerrunner$outputconverter.write(task.java:1667)在apred.maptask$NewOutputCollector.Close(maptask.java:723)在org.apache.hadoop.mapred.maptask.runnewmapper(maptask.java:793)在org.apache.hadoop.mapred.maptask.run(maptask.java:341)在org.apache.hadoop.mapred.maptask.run(maptask.java:341)在org.apache.hadoop.mapred.yarnchild$2.run(yarnchild.java:164)在

这是我的代码，错误信息如下。知道吗？？我认为问题在于mapper和reducer的输出类的配置，输入文件是一个文件中的数字列表。如有需要，将提供更多细节。程序在朋友之间找到共同的朋友

Answer 1

删除代码中的Job.SetCombinerClass（IntSumReducer.Class）；可以解决此问题