not able to run wordcount example in mapreduce 2.x - hadoop

Question

I am trying to execute mapreduce word count exaple in mapreduce 2.x in java.... I had create the jar but while executing it is showing the error like WordMapper class not found in my package but I had declared that in my package.....please help me to solve the issue......
this is my WordCount driver code :
package com.mapreduce2.x;
public class WordCount {
public static void main(String args[]) throws IOException, ClassNotFoundException, InterruptedException
{
Configuration conf=new Configuration();
org.apache.hadoop.mapreduce.Job job= new org.apache.hadoop.mapreduce.Job(conf, "Word_Count");
job.setMapperClass(WordMapper.class);
job.setReducerClass(WordReducer.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
org.apache.hadoop.mapreduce.lib.input.FileInputFormat.setInputPaths(job, new Path(args[0]));
org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.waitForCompletion(true);
}}
And this is my WordMapper Class :-
public class WordMapper extends Mapper<LongWritable, Text, Text,IntWritable>{
private final static IntWritable one=new IntWritable(1);
private Text word=new Text();
public void map(LongWritable key, Text value, org.apache.hadoop.mapreduce.Reducer.Context context) throws IOException, InterruptedException
{
String line=value.toString();
StringTokenizer tokenizer=new StringTokenizer(line);
while(tokenizer.hasMoreTokens())
{
word.set(tokenizer.nextToken());
context.write(word, one);
}
}}
WordReducer code -
public class WordReducer extends Reducer<Text, IntWritable, Text, IntWritable>{
public void reduce(Text key, Iterator<IntWritable> values,Context context) throws IOException, InterruptedException
{
int sum =0;
while(values.hasNext())
{
sum= sum+values.next().get();
}
context.write(key, new IntWritable(sum));
}}
it is showing the folowing error while executing-
15/05/29 10:12:26 INFO mapreduce.Job: map 0% reduce 0%
15/05/29 10:12:33 INFO mapreduce.Job: Task Id : attempt_1432876892622_0005_m_000000_0, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class com.mapreduce2.x.WordMapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2076)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:742)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
Caused by: java.lang.ClassNotFoundException: Class com.mapreduce2.x.WordMapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1982)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2074)
... 8 more

Answer 1

Include the class name while running the JAR file or you can specify the main class name while creating the JAR file.
If you are running without class name then specify the class name while running the JAR.
Use the command
hadoop jar word.jar com.mapreduce2.x.WordMapper /input /output
Here word.jar is the JAR file name.
OR
you can also include the main class name while creating a jar file.
Steps:
File --> export --> JAR --> location --> then click next --> it asks for selecting main class --> select the class and click OK
After that you can run the jar file with the command
hadoop jar word.jar /input /output
Hope this solves your issue.

Answer 2

Try adding the commented line below
Job job = new Job(conf, "wordcount");
//job.setJarByClass(WordCount.class);
It worked for me

Answer 3

You can try this one:(IN Linux/Unix)
Remove the package name in the java code.
Inside the directory which contains the java program, create a new directory called classes. ex: Hadoop-Wordcount -> classes , WordCount.java
compile: javac -classpath $HADOOP_HOME/hadoop-common-2.7.1.jar:$HADOOP_HOME/hadoop-mapreduce-client-core-2.7.1.jar:$HADOOP_HOME/hadoop-annotations-2.7.1.jar:$HADOOP_HOME/commons-cli-1.2.jar -d ./classes WordCount.java
create a jar jar -cvf wordcount.jar -C ./classes/ .
5.run bin/hadoop jar $HADOOP_HOME/Hadoop-WordCount/wordcount.jar WordCount input output