Exception in thread “main“ java.lang.NoSuchMethodException

今天编程又遇到问题了，完整报错如下：

Exception in thread "main" java.lang.NoSuchMethodException: org.apache.zookeeper.server.quorum.QuorumPeer.main([Ljava.lang.String;)
        at java.lang.Class.getMethod(Class.java:1786)
        at org.apache.hadoop.util.RunJar.run(RunJar.java:215)
        at org.apache.hadoop.util.RunJar.main(RunJar.java:136)

解决方法：我们可以将之前的jar包删除，然后重新创建一个jar包，并在创建jar包时设置一个主类

 再跑一次应该就能成功了，如果还不行的话，可以将驱动类（如下）job的输入路径与输出路径互换一下

package S1;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.DoubleWritable;

import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

import java.io.IOException;

public class main1 {
    public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException {
        Job job= Job.getInstance(new Configuration());
        job.setJarByClass(main1.class);

        job.setMapperClass(map1.class);
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(DoubleWritable.class);

        //指定job的reducer和输出类型
        job.setReducerClass(reducer1.class);
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(Text.class);

        //指定job的输入和输出路径
        FileInputFormat.setInputPaths(job,new Path(args[1]));
        FileOutputFormat.setOutputPath(job,new Path(args[0]));

        //执行任务
        job.waitForCompletion(true);
    }
}

 再跑一次就出来了