CODEWITHSUNDEEP
hadoop
Robin
Robin

Reputation: 67

hadoop compiling

I'm new to hadoop. I got this code from net

import java.io.IOException;
import java.util.*;

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.*;

public class Gender {

   private static String genderCheck = "female";

   public static class Map extends MapReduceBase implements Mapper {
       private final static IntWritable one = new IntWritable(1);
       private Text locText = new Text();

       public void map(LongWritable key, Text value, OutputCollector output, Reporter reporter) throws IOException {
           String line = value.toString();
           String location = line.split(",")[14] + "," + line.split(",")[15];
           long male = 0L;
           long female = 0L;
           if (line.split(",")[17].matches("\d+") && line.split(",")[18].matches("\d+")) {
               male = Long.parseLong(line.split(",")[17]);
               female = Long.parseLong(line.split(",")[18]);
           }
           long diff = male - female;
           locText.set(location);
           if (Gender.genderCheck.toLowerCase().equals("female") && diff < 0) {
               output.collect(locText, new LongWritable(diff * -1L));
           }
           else if (Gender.genderCheck.toLowerCase().equals("male") && diff
> 0) {
               output.collect(locText, new LongWritable(diff));
           }
       }    }

   public static void main(String[] args) throws Exception {
       JobConf conf = new JobConf(Gender.class);
       conf.setJobName("gender");
       conf.setOutputKeyClass(Text.class);
       conf.setOutputValueClass(LongWritable.class);
       conf.setMapperClass(Map.class);

       if (args.length != 3) {
           System.out.println("Usage:");
           System.out.println("[male/female] /path/to/2kh/files /path/to/output");
           System.exit(1);
       }

       if (!args[0].equalsIgnoreCase("male") && !args[0].equalsIgnoreCase("female")) {
           System.out.println("first argument must be male or female");
           System.exit(1);
       }
       Gender.genderCheck = args[0];

       conf.setInputFormat(TextInputFormat.class);
       conf.setOutputFormat(TextOutputFormat.class);
       FileInputFormat.setInputPaths(conf, new Path(args[1]));
       FileOutputFormat.setOutputPath(conf, new Path(args[2]));
       JobClient.runJob(conf);    }

}

when I compile this code using "javac -cp /usr/local/hadoop/hadoop-core-1.0.3.jar Gender.java"

getting the following error:

"Gender.Map is not abstract and does not override abstract method map(java.lang.Object,java.lang.Object,org.apache.hadoop.mapred.OutputCollector,org.apache.hadoop.mapred.Reporter) in org.apache.hadoop.mapred.Mapper public static class Map extends MapReduceBase implements Mapper "

How can I compile it correctly?

Upvotes: 1

Views: 859

Answers (2)

Aditi Gupta
Aditi Gupta

Reputation: 66

Change the map class as follows:

public static class Map extends MapReduceBase implements Mapper <Input key, Input value, Output Key , Output Value>

In your case the input key is LongWritable, Input value is Text, Output Key is Text , Output value is LongWritable 

public static class Map extends MapReduceBase implements Mapper <LongWritable, Text, Text,LongWritable>

Upvotes: 0

Amar
Amar

Reputation: 12020

Change the class Maper class declaration as follows:

public static class Map extends MapReduceBase implements Mapper<LongWritable,Text,Text, LongWritable>

If you do not specify any specific class names, you would need to have the map function as follows:

@Override
public void map(Object arg0, Object arg1, OutputCollector arg2, Reporter arg3) throws IOException {
    // TODO Auto-generated method stub
}

Now, the specific types denote here the expected input key-value pair types and the output key-value types from the mapper.

In your case the input key-value pair are LongWritable-Text.

And, guessing from your output.collect method calls, your mapper output key-value pair is Text-LongWritable.

Hence, your Map class shall implememnt Mapper<LongWritable,Text,Text, LongWritable>.

There was one more error in your code -

Using "\d+" will not compile as \d has no meaning, after backslash it expects a special escape sequence, so I guess for you the following should work: line.split(",")[17].matches("\\d+")

Upvotes: 1

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