mapreduce java.lang.Exception: java.lang.RuntimeException: java.lang.NoSuchMethodException

最新推荐文章于 2021-08-06 11:26:27 发布

caiandyong

最新推荐文章于 2021-08-06 11:26:27 发布

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分类专栏： hadoop 文章标签： NoSuchMethodExceptio mapreduce exception

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执行reduce的时候出现如下错误:

java.lang.Exception: java.lang.RuntimeException: java.lang.NoSuchMethodException: org.cy.pack1.MR1_Normalization$Reduce_Normalization.<init>()
   at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
   at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:529)
Caused by: java.lang.RuntimeException: java.lang.NoSuchMethodException: org.cy.pack1.MR1_Normalization$Reduce_Normalization.<init>()
   at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:131)
   at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:611)
   at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:389)
   at org.apache.hadoop.mapred.LocalJobRunner$Job$ReduceTaskRunnable.run(LocalJobRunner.java:319)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
   at java.util.concurrent.FutureTask.run(FutureTask.java:166)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
   at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.NoSuchMethodException: org.cy.pack1.MR1_Normalization$Reduce_Normalization.<init>()
   at java.lang.Class.getConstructor0(Class.java:2800)
   at java.lang.Class.getDeclaredConstructor(Class.java:2043)
   at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:125)
   ... 9 more

原因: 没有在reduce类前面添加static关键字,因为在main函数中是按照类名调用方法的,所以要将reduce内部类声明为静态的.