Question

我正在尝试运行一个简单的MapReduce程序来计算男性和女性的平均年龄。当我试图执行它时，它给了我Class Not Found Exception（泰坦尼克号类）。我发现很多问题提供了类似的答案，并基于我修改了我的程序，但它仍然给我同样的错误。如果有人可以调试它，那将非常有用。

import java.io.IOException;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;

public class Titanic{
public static class Map extends Mapper<LongWritable, Text, Text, IntWritable>{
    private Text category = new Text();
    public void map(LongWritable key, Text text, Context context) throws IOException, InterruptedException{
        String line = text.toString();
        String str[] = line.split(",");
        if(str[4] == "male"){
            category.set(str[4]);
        }else{
            category.set(str[4]);
        }
        IntWritable value = new IntWritable(Integer.parseInt(str[5]));
        context.write(category,value);
    }

}

public static class Reduce extends Reducer<Text, IntWritable, Text, FloatWritable>{

    public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException{
        float average = 0;
        int count =0;
        for(IntWritable val : values){
                average = average+val.get();
                count = count + 1;              
        }
        average =average/count;
        context.write(key, new FloatWritable(average));

    }   

}

public static void main(String[] args) throws Exception{
    Configuration conf = new Configuration();
    Job job = Job.getInstance(conf, "titanic");
    job.setJarByClass(Titanic.class);
    job.setMapperClass(Map.class);
    job.setReducerClass(Reduce.class);
    job.setMapOutputKeyClass(Text.class);
    job.setMapOutputValueClass(IntWritable.class);
    FileInputFormat.addInputPath(job, new Path(args[0]));
    FileOutputFormat.setOutputPath(job, new Path(args[1]));
    System.exit(job.waitForCompletion(true) ? 0 : 1);       
}

}

以下是我在其上执行的命令。

创建一个jar文件：

jar cf example/titanic/titanic.jar example/titanic/Titanic*.class

执行jar文件：

bin/hadoop jar example/titanic/titanic.jar Titanic /user/akhil/titanic/input/TitanicData.txt /user/akhil/titanic/output/

Answer 1

删除*：

jar cf example/titanic/titanic.jar example/titanic/Titanic.class

Answer 2

罐子搞砸了。如果您的类属于默认包，则它们不应位于example/titanic/目录下，而应位于根目录下。

Hadoop Java错误：线程“main”中的异常java.lang.ClassNotFoundException：泰坦尼克号

2 个答案: