Question

我正在为以下代码执行mapreduce。当我运行这个Job时，每件事情都可以。但是输出显示0 0.我怀疑这可能是由于TrypparseInt（）方法由于之前未定义而快速修复。最初没有TryparseInt（）的方法。所以我创建了一个，任何人都可以检查代码是否正确，特别是TryParseInt方法，并告诉我任何建议成功运行该程序。

输入如下：

先谢谢

    import java.io.IOException;

import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.mapreduce.Mapper;
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.Reducer;
import org.apache.hadoop.io.LongWritable;


public class MaxPubYear {

public static class MaxPubYearMapper extends Mapper<LongWritable , Text, IntWritable,Text>
    {
        public void map(LongWritable key, Text value , Context context)

                throws IOException, InterruptedException
                {
            String delim = "\t";
            Text valtosend = new Text();
            String tokens[] = value.toString().split(delim);
            if (tokens.length == 2)
            {
                valtosend.set(tokens[0] + ";"+ tokens[1]);
                context.write(new IntWritable(1), valtosend);
            }

                }      
    }


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

        public void reduce(IntWritable key, Iterable<Text> values , Context context) throws IOException, InterruptedException
        {
            int maxiValue = Integer.MIN_VALUE;
            String maxiYear = "";
            for(Text value:values)          {
                String token[] = value.toString().split(";");
                if(token.length == 2 && TryParseInt(token[1]).intValue()> maxiValue)
                {
                    maxiValue = TryParseInt(token[1]);
                    maxiYear = token[0];
                }
            }
            context.write(new Text(maxiYear), new IntWritable(maxiValue));
        }
    }

public static void main(String[] args) throws Exception  {

            Configuration conf = new Configuration();
            Job Job = new Job(conf, "Maximum Publication year");
            Job.setJarByClass(MaxPubYear.class);

            Job.setOutputKeyClass(Text.class);
            Job.setOutputValueClass(IntWritable.class);

            Job.setMapOutputKeyClass(IntWritable.class);
            Job.setMapOutputValueClass(Text.class);

            Job.setMapperClass(MaxPubYearMapper.class);              
            Job.setReducerClass(MaxPubYearReducer.class);

            FileInputFormat.addInputPath(Job,new Path(args[0]));
            FileOutputFormat.setOutputPath(Job,new Path(args[1]));
            System.exit(Job.waitForCompletion(true)?0:1);                

        }

public static Integer TryParseInt(String string) {
    // TODO Auto-generated method stub
    return(0);
}
    }

Answer 1

这些错误正是他们所说的：对于三个'无法解析为类型'错误，你可能忘记导入正确的类。错误2仅表示类TryParseInt(String)中没有方法MaxPubYear.MaxPubYearReducer，您必须在那里创建一个方法。

无法识别此程序中的错误

1 个答案: