面對編譯錯誤Hadoop Junit測試

我是hadoop的新手，我正在學習haddop權威指南。我正在使用MRunit進行單元測試，但在進行reduce任務測試時，我正面臨編譯錯誤。面對編譯錯誤Hadoop Junit測試

下面是我的降低的java文件：MaxTemperatureReducer.java

package org.priya.mapred.mapred; 

import java.io.IOException; 
import java.util.Iterator; 
import org.apache.hadoop.io.IntWritable; 
import org.apache.hadoop.io.Text; 
//import org.apache.hadoop.mapred.MRBench.Reduce; 
import org.apache.hadoop.mapreduce.Reducer; 

public class MaxTemperatureReducer extends Reducer<Text, IntWritable , Text, IntWritable> { 

    public void reduce(Text key,Iterator<IntWritable> values, Context context) throws InterruptedException ,IOException 
    { 
     int maxValue = Integer.MIN_VALUE; 
     while(values.hasNext()) 
     { 
      IntWritable value =values.next(); 
      if(maxValue >= value.get()) 
      { 
       maxValue= value.get(); 
      } 
     } 

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

    } 

}

下面是我的JUnit進行測試文件：MaxTemperatureReducerTest.java

package org.priya.mapred.mapred; 

import static org.junit.Assert.*; 
import java.util.ArrayList; 
import org.junit.Test; 
import org.apache.hadoop.io.IntWritable; 
import org.apache.hadoop.io.Text; 
import org.apache.hadoop.mapreduce.Reducer; 
//import org.apache.hadoop.mrunit.ReduceDriver; 
import org.apache.hadoop.mrunit.ReduceDriver; 
//import org.apache.hadoop.mrunit.mapreduce.MapReduceDriver; 

public class MaxTemperatureReducerTest { 

    @Test 
    public void reducerTestValid() 
    { 
     ArrayList<IntWritable> listOfValues = new ArrayList<IntWritable>(); 
     listOfValues.add(new IntWritable(20)); 
     listOfValues.add(new IntWritable(30)); 
     listOfValues.add(new IntWritable(40)); 
     listOfValues.add(new IntWritable(60)); 
     new ReduceDriver<Text ,IntWritable , Text, IntWritable>() 
         .withReducer(new MaxTemperatureReducer()) 
         .withInput(new Text("1950"),listOfValues) 
         .withOutput(new Text("1950"), new IntWritable(60)); 



    } 

}

而我傳遞reduceclass即新MaxTemperatureReducer的一個實例（）給我的reducerdriver使用，withReducer（）方法的驅動類。我正在收到編譯錯誤。

The method withReducer(Reducer<Text,IntWritable,Text,IntWritable>) in the type ReduceDriver<Text,IntWritable,Text,IntWritable> is not applicable for the arguments (MaxTemperatureReducer)

請幫我，我可以看到MaxTemperatureMapper類擴展了減速類，我不能understatnd爲什麼withReducer（）方法不接受MaxTemperatureReducer實例。

感謝， Priyaranjan

來源

2014-02-07 priyaranjan