Hi,
I am new to Hadoop so this might be an easy question for someone to
help me with.
I continually am getting this exception (my code follows below)
java.io.IOException: Type mismatch in key from map: expected
org.apache.hadoop.io.Text, recieved org.apache.hadoop.io.LongWritable
at org.apache.hadoop.mapred.MapTask
$MapOutputBuffer.collect(MapTask.java:807)
at org.apache.hadoop.mapred.MapTask
$NewOutputCollector.write(MapTask.java:504)
at
org
.apache
.hadoop
.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
at org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:124)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:144)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:583)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
at org.apache.hadoop.mapred.Child.main(Child.java:170)
Running 0.20.1
I have a text file with lines of data separated by carriage returns.
This is properly stored in a directory within HDFS. I only have a
Mapping task for processing this file, after the mapping is done it
should go straight to output, No reduce or combiner functions.
I am just trying to test to see if this will run. The mapper just
takes the data sent to it and adds it back to the collector as 2 text
values.
--------------------
My Mapper:
--------------------
public class MyTestMapper extends Mapper<LongWritable,Text,Text,Text> {
public void map(Object key, Text value, Context context) throws
IOException, InterruptedException {
String key = key.toString();
String line = value.toString();
String id = extractId(line);
String reformattedLine = reformatLine(line);
context.write(new Text(id), new Text(reformattedLine));
}
}
--------------------
My job submission code:
-------------------------------------
Job job = new Job(conf);
job.setJarByClass(MyTestMapper.class);
job.setMapperClass(MyTestMapper.class);
FileInputFormat.addInputPath(job, new Path("/myDir/sample.txt"));
FileOutputFormat.setOutputPath(job, new Path("/myDir/output/
results-"+System.currentTimeMillis()+".txt"));
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
job.submit();
