驱动程序类编译错误 - hadoop Mapreduce [英] Driver class compilation error - hadoop Mapreduce

问题描述

我有3个.java文件

  1）Mapper.java 
 2）Reducer.java 
 3）Driver.java 
  

我试图在Driver类中使用命令行编译hadoop mapreduce程序，但它显示下面的错误

  Driver.java:39：错误：找不到符号
 job.setMapperClass（Mapper。类）; 
 ^ 
 symbol：class Mapper 
 location：class Driver 
 Driver.java:40：error：找不到符号
 job.setReducerClass（Reducer.class）; 
  

如何解决上面的错误。下面是Driver类中的run方法

  public boolean runnerParsing（String inputPath，String outputPath）throws IOException，ClassNotFoundException，InterruptedException {
 Configuration conf = new Configuration（）; 
 
 Job job = new Job（conf，Parsing）; 
 job.setJarByClass（Driver.class）; 
 
 
 job.setOutputKeyClass（Text.class）; 
 job.setOutputValueClass（Text.class）; 
 
 job.setMapperClass（Mapper.class）; 
 job.setReducerClass（Reducer.class）; 
 //job.setNumReduceTasks(0）; 
 
 job.setInputFormatClass（TextInputFormat.class）; 
 job.setOutputFormatClass（TextOutputFormat.class）; 
 
 FileInputFormat.addInputPath（job，new Path（inputPath））; 
 FileOutputFormat.setOutputPath（job，new Path（outputPath））; 
 
 return job.waitForCompletion（true）; 
 
 
 $ / code $ / pre 
 
解决方案
需要编译所有java文件，如下所示：
 
 
 
  javac -classpath /usr/local/hadoop/hadoop-core-1.2.1.jar  - d compiled_classes Driver.java Mapper.java Reducer.java  
 
 
 
请注意，根据您安装Hadoop的方式，您的classpath值可能会稍有变化。 / p> 
 
 
如果您需要进一步帮助，请查看本文，这可能会对您有所帮助：
  http://www.bigdatatutes.com/getting-started-with-big-data/  
 
I have 3 .java file
1) Mapper.java
2) Reducer.java
3) Driver.java
I am trying to compile hadoop mapreduce program at command line using Driver class but it is showing below error 
Driver.java:39: error: cannot find symbol
        job.setMapperClass(Mapper.class);
                           ^
  symbol:   class Mapper
  location: class Driver
Driver.java:40: error: cannot find symbol
        job.setReducerClass(Reducer.class);
How can I solve above error.Below is run method in Driver class
public boolean runnerParsing(String inputPath, String outputPath) throws IOException, ClassNotFoundException, InterruptedException {
         Configuration conf = new Configuration();

        Job job = new Job(conf, "Parsing");
        job.setJarByClass(Driver.class);


        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);

        job.setMapperClass(Mapper.class);
        job.setReducerClass(Reducer.class);
        //job.setNumReduceTasks(0);

        job.setInputFormatClass(TextInputFormat.class);
        job.setOutputFormatClass(TextOutputFormat.class);

        FileInputFormat.addInputPath(job, new Path(inputPath));
        FileOutputFormat.setOutputPath(job, new Path(outputPath));

        return job.waitForCompletion(true);

     }

解决方案
You will need to compile all java files as below:

javac -classpath /usr/local/hadoop/hadoop-core-1.2.1.jar -d compiled_classes Driver.java Mapper.java Reducer.java

Please note that your classpath value may change slightly depending on how you install Hadoop.

If you need further help, please have a look at this article which might help you:
http://www.bigdatatutes.com/getting-started-with-big-data/

                        
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