how did you package and compile your jar ? did you specify the main class
for the JAR file you generated ?
2013/12/13 ch huang <justlo...@gmail.com>
> hi,maillist:
>
> i rewrite WordCount.java and try to compile and run it but
> it say not find main class ,why?
>
> [root@CHBM224 myMR]# cat WordCount.java
> import java.io.IOException;
> import java.util.StringTokenizer;
> import org.apache.hadoop.conf.Configuration;
> import org.apache.hadoop.conf.Configured;
> import org.apache.hadoop.fs.Path;
> import org.apache.hadoop.io.IntWritable;
> import org.apache.hadoop.io.Text;
> import org.apache.hadoop.mapreduce.Job;
> import org.apache.hadoop.mapreduce.Mapper;
> import org.apache.hadoop.mapreduce.Reducer;
> import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
> import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
> import org.apache.hadoop.util.GenericOptionsParser;
> import org.apache.hadoop.util.ToolRunner;
> import org.apache.hadoop.util.Tool;
> public class WordCount extends Configured implements Tool {
> public static class TokenizerMapper
> extends Mapper<Object, Text, Text, IntWritable>{
> private final static IntWritable one = new IntWritable(1);
> private Text word = new Text();
> public void map(Object key, Text value, Context context
> ) throws IOException, InterruptedException {
> StringTokenizer itr = new StringTokenizer(value.toString());
> while (itr.hasMoreTokens()) {
> word.set(itr.nextToken());
> context.write(word, one);
> }
> }
> }
> public static class IntSumReducer
> extends Reducer<Text,IntWritable,Text,IntWritable> {
> private IntWritable result = new IntWritable();
> public void reduce(Text key, Iterable<IntWritable> values,
> Context context
> ) throws IOException, InterruptedException {
> int sum = 0;
> for (IntWritable val : values) {
> sum += val.get();
> }
> result.set(sum);
> context.write(key, result);
> }
> }
> private static void usage() throws IOException {
> System.err.println("teragen <num rows> <output dir>");
> }
> public int run(String[] args) throws IOException, InterruptedException,
> ClassN
> otFoundException {
> Job job = Job.getInstance(getConf());
> if (args.length != 2) {
> usage();
> return 2;
> }
> job.setJobName("wordcount");
> job.setJarByClass(WordCount.class);
> job.setMapperClass(TokenizerMapper.class);
> job.setCombinerClass(IntSumReducer.class);
> job.setReducerClass(IntSumReducer.class);
> job.setOutputKeyClass(Text.class);
> job.setOutputValueClass(IntWritable.class);
> FileInputFormat.addInputPath(job, new Path(args[0]));
> FileOutputFormat.setOutputPath(job, new Path(args[1]));
> return job.waitForCompletion(true) ? 0 : 1;
> }
> public static void main(String[] args) throws Exception {
> int res = ToolRunner.run(new Configuration(), new WordCount(),
> args);
> System.exit(res);
> }
> }
> [root@CHBM224 myMR]# javac -cp
> '/usr/lib/hadoop/*:/usr/lib/hadoop-mapreduce/*' -d ../test WordCount.java
> [root@CHBM224 myMR]# hadoop ../test/WordCount
> Error: Could not find or load main class ...test.WordCount
>
