Type mismatch in value from map: expected org.apache.hadoop.io.LongWritable, received

报错信息

java.lang.Exception: java.io.IOException: Type mismatch in value from map: expected org.apache.hadoop.io.LongWritable, received CovidCountBean
	at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:491)
	at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:551)
Caused by: java.io.IOException: Type mismatch in value from map: expected org.apache.hadoop.io.LongWritable, received CovidCountBean
	at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1084)
	at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:721)
	at org.apache.hadoop.mapreduce.task.TaskInputOutputContextImpl.write(TaskInputOutputContextImpl.java:89)
	at org.apache.hadoop.mapreduce.lib.map.WrappedMapper$Context.write(WrappedMapper.java:112)
	at CovidSumMapper.map(CovidSumMapper.java:37)
	at CovidSumMapper.map(CovidSumMapper.java:7)
	at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146)
	at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:793)
	at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
	at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:270)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
[INFO] [org.apache.hadoop.mapreduce.Job.monitorAndPrintJob(Job.java:1640)] reduce.Job - Job job_local155779917_0001 running in uber mode : false
[INFO] [org.apache.hadoop.mapreduce.Job.monitorAndPrintJob(Job.java:1647)] reduce.Job -  map 0% reduce 0%
[INFO] [org.apache.hadoop.mapreduce.Job.monitorAndPrintJob(Job.java:1660)] reduce.Job - Job job_local155779917_0001 failed with state FAILED due to: NA
[INFO] [org.apache.hadoop.mapreduce.Job.monitorAndPrintJob(Job.java:1665)] reduce.Job - Counters: 0

Process finished with exit code 1

原因：

Map的输出与Reduce的输入不一致

解决方法：

1、检查map的输出类型和reduce的输出类型
2、检查驱动类中的类型设置是否一致

        //指定mapper阶段输出的key value数据类型
        job.setMapOutputKeyClass(Text.class);
        job.setMapOutputValueClass(CovidCountBean.class);

        //指定reducer阶段输出的key value数据类型，也是mr程序最终的输出数据类型
        job.setOutputKeyClass(Text.class);
        job.setOutputValueClass(CovidCountBean.class);