“线程中的异常”；“主要”；java.lang.ClassCastException:WordCount不能强制转换为org.apache.hadoop.util.Tool

我正在尝试执行新的api mapreduce wordcount示例。这是我的程序，我使用hadoop-core-1.0.4.jar作为插件

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

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.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;




public class NewWordCount {

    public static class WordMapper extends Mapper<LongWritable, Text, Text, IntWritable> {

        @Override
        protected void map(LongWritable key, Text value, Context context)
                throws IOException, InterruptedException {
            String line = value.toString();
            String[] words = line.split("\\W+");
            for (String word : words) {
                context.write(new Text(word), new IntWritable(1));
            }
        }

    }

    public static class WordReducer extends Reducer<Text, IntWritable, Text, IntWritable> {

        protected void reduce(Text key,  Iterator<IntWritable> values,
                Context context)
                throws IOException, InterruptedException {

            /*int sum = 0;
            for (IntWritable value:values) {
                sum += value.get();
            }*/
            int sum = 0;
            while (values.hasNext()) {
                sum += values.next().get();
            }

            context.write(key, new IntWritable(sum));

        }

    }



        public static void main(String[] args) throws Exception
        {
            Configuration conf = new Configuration();
            int exitCode=ToolRunner.run((Tool) new NewWordCount(), args);

            System.exit(exitCode);
        }
        public int run(String[] args) throws IOException, InterruptedException, ClassNotFoundException
        {

            Path inputPath=new Path(args[0]);
            Path outputPath=new Path(args[1]);
            Configuration conf = new Configuration();
            Job job = new Job(conf,"word count");
            job.setJarByClass(NewWordCount.class);
            job.setMapperClass(WordMapper.class);
            job.setReducerClass(WordReducer.class);
            job.setOutputKeyClass(Text.class);
            job.setOutputValueClass(IntWritable.class);

            FileInputFormat.setInputPaths(job,inputPath);
              FileOutputFormat.setOutputPath(job,outputPath);
            job.setNumReduceTasks(2);
        //  job.setPartitionerClass(VCPartitioner.class);
            job.waitForCompletion(true);
            //job.submit();
            return 0;
        }

    }

---

有人能告诉我如何解决这个错误吗？提前感谢。

您不能强制转换

NewWordCount

，因为它没有实现

工具

接口

删除此行：

int exitCode=ToolRunner.run((Tool) new NewWordCount(), args);

您只需使用

main

方法（将run方法的内容复制到main之后）

要运行它：

hadoop NewWordCount input output

---

我试过你的密码。但我仍然无法转换为org.apache.hadoop.util.Tool error.Casting to Tool我在main方法中执行这一行：int exitCode=ToolRunner.run（（Tool）NewWordCount（），args）；

hadoop NewWordCount input output