Question

我的执行文件是：

package hadoop; 

import java.util.*; 

import java.io.IOException; 
import java.io.IOException; 

import org.apache.hadoop.fs.Path; 
import org.apache.hadoop.conf.*; 
import org.apache.hadoop.io.*; 
import org.apache.hadoop.mapred.*; 
import org.apache.hadoop.util.*; 
import javax.lang.model.util.Elements;
public class ProcessUnits 
{ 
   //Mapper class 
   public static class E_EMapper extends MapReduceBase implements 
   Mapper<LongWritable ,/*Input key Type */ 
   Text,                /*Input value Type*/ 
   Text,                /*Output key Type*/ 
   IntWritable>        /*Output value Type*/ 
   { 

      //Map function 
      public void map(LongWritable key, Text value, 
      OutputCollector<Text, IntWritable> output,   
      Reporter reporter) throws IOException 
      { 
         String line = value.toString(); 
         String lasttoken = null; 
         StringTokenizer s = new StringTokenizer(line,"\t"); 
         String year = s.nextToken(); 

         while(s.hasMoreTokens())
            {
               lasttoken=s.nextToken();
            } 

         int avgprice = Integer.parseInt(lasttoken); 
         output.collect(new Text(year), new IntWritable(avgprice)); 
      } 
   } 


   //Reducer class 
   public static class E_EReduce extends MapReduceBase implements 
   Reducer< Text, IntWritable, Text, IntWritable > 
   {  

      //Reduce function 
      public void reduce( Text key, Iterator <IntWritable> values, 
         OutputCollector<Text, IntWritable> output, Reporter reporter) throws IOException 
         { 
            int maxavg=30; 
            int val=Integer.MIN_VALUE; 

            while (values.hasNext()) 
            { 
               if((val=values.next().get())>maxavg) 
               { 
                  output.collect(key, new IntWritable(val)); 
               } 
            } 

         } 
   }  


   //Main function 
   public static void main(String args[])throws Exception 
   { 
      JobConf conf = new JobConf(Eleunits.class); 

      conf.setJobName("max_eletricityunits"); 
      conf.setOutputKeyClass(Text.class);
      conf.setOutputValueClass(IntWritable.class); 
      conf.setMapperClass(E_EMapper.class); 
      conf.setCombinerClass(E_EReduce.class); 
      conf.setReducerClass(E_EReduce.class); 
      conf.setInputFormat(TextInputFormat.class); 
      conf.setOutputFormat(TextOutputFormat.class); 

      FileInputFormat.setInputPaths(conf, new Path(args[0])); 
      FileOutputFormat.setOutputPath(conf, new Path(args[1])); 

      JobClient.runJob(conf); 
   } 
}

当我用以下命令编译时：

javac -classpath /home/javier/entrada/hadoop-core-1.2.1.jar -d / home / javier / units /home/javier/entrada/ProcessUnits.java

我遇到以下错误：

javac -classpath /home/javier/entrada/hadoop-core-1.2.1.jar -d /home/javier/units /home/javier/entrada/ProcessUnits.java
/home/javier/entrada/ProcessUnits.java:72: error: cannot find symbol
      JobConf conf = new JobConf(Eleunits.class); 
                                 ^
  symbol:   class Eleunits
  location: class ProcessUnits
1 error

我的hadoop版本是2.9.2，而我的Java版本是1.8.0_191

当我用eclipse打开它并查看它时，找不到Eleunits.class的导入

Answer 1

我的hadoop版本是2.9.2，而我的Java版本是1.8.0_191

首先，hadoop-core-1.2.1.jar的构建甚至还没有想到Hadoop 2.9.2，因此您将需要一个新的JAR

当我用eclipse打开它并查看它时，找不到Eleunits.class的导入

不清楚您为什么不一直使用Eclipse！即使不使用Maven或Gradle来获取Hadoop的正确库版本，也令我感到恐惧……但是Eclipse可能并没有说谎。您只显示了一个类，而该类未称为Eleunits，除了从其他地方复制之外，我不确定您如何获得该值

此外，主类应该extends Configured implements Tool，正如您在其他MapReduce示例中所发现的

Javac找不到作业类别的符号

1 个答案: