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From Harit Himanshu <harit.himan...@gmail.com>
Subject Hadoop : java.lang.ClassCastException: org.apache.hadoop.io.LongWritable cannot be cast to org.apache.hadoop.io.Text
Date Thu, 02 Aug 2012 19:59:31 GMT
StackOverflow link -
http://stackoverflow.com/questions/11784729/hadoop-java-lang-classcastexception-org-apache-hadoop-io-longwritable-cannot

----------

My program looks like

public class TopKRecord extends Configured implements Tool {

    public static class MapClass extends Mapper<Text, Text, Text, Text> {

        public void map(Text key, Text value, Context context) throws
IOException, InterruptedException {
            // your map code goes here
            String[] fields = value.toString().split(",");
            String year = fields[1];
            String claims = fields[8];

            if (claims.length() > 0 && (!claims.startsWith("\""))) {
                context.write(new Text(year.toString()), new
Text(claims.toString()));
            }
        }
    }
   public int run(String args[]) throws Exception {
        Job job = new Job();
        job.setJarByClass(TopKRecord.class);

        job.setMapperClass(MapClass.class);

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

        job.setJobName("TopKRecord");
        job.setMapOutputValueClass(Text.class);
        job.setNumReduceTasks(0);
        boolean success = job.waitForCompletion(true);
        return success ? 0 : 1;
    }

    public static void main(String args[]) throws Exception {
        int ret = ToolRunner.run(new TopKRecord(), args);
        System.exit(ret);
    }
}

The data looks like

"PATENT","GYEAR","GDATE","APPYEAR","COUNTRY","POSTATE","ASSIGNEE","ASSCODE","CLAIMS","NCLASS","CAT","SUBCAT","CMADE","CRECEIVE","RATIOCIT","GENERAL","ORIGINAL","FWDAPLAG","BCKGTLAG","SELFCTUB","SELFCTLB","SECDUPBD","SECDLWBD"
3070801,1963,1096,,"BE","",,1,,269,6,69,,1,,0,,,,,,,
3070802,1963,1096,,"US","TX",,1,,2,6,63,,0,,,,,,,,,
3070803,1963,1096,,"US","IL",,1,,2,6,63,,9,,0.3704,,,,,,,
3070804,1963,1096,,"US","OH",,1,,2,6,63,,3,,0.6667,,,,,,,

On running this program I see the following on console

12/08/02 12:43:34 INFO mapred.JobClient: Task Id :
attempt_201208021025_0007_m_000000_0, Status : FAILED
java.lang.ClassCastException: org.apache.hadoop.io.LongWritable cannot
be cast to org.apache.hadoop.io.Text
    at com.hadoop.programs.TopKRecord$MapClass.map(TopKRecord.java:26)
    at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:764)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:370)
    at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:396)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
    at org.apache.hadoop.mapred.Child.main(Child.java:249)

I believe that the Class Types are mapped correctly, Class
Mapper<http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/mapreduce/Mapper.html>
,

Please let me know what is that I am doing wrong here?


Thank you

+ Harit Himanshu

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