今天運行hadoop突然出現一個問題!
java.lang.RuntimeException: java.lang.NoSuchMethodException: tfidf$Reduce.<init>()
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:115)
at org.apache.hadoop.mapred.Task$OldCombinerRunner.combine(Task.java:1423)
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.sortAndSpill(MapTask.java:1436)
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.flush(MapTask.java:1298)
at org.apache.hadoop.mapred.MapTask.runOldMapper(MapTask.java:437)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:372)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
Caused by: java.lang.NoSuchMethodException: tfidf$Reduce.<init>()
at java.lang.Class.getConstructor0(Class.java:2715)
at java.lang.Class.getDeclaredConstructor(Class.java:1987)
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:109)
... 10 more
閱讀錯誤提示可以看出是構造函數出了問題,在網上找了好久都沒有解決問題。最後通過仔細觀察終於讓我發現一個小細節。就是在定義自己的map時沒有使用static關鍵字,所以出現了以上的錯誤。添加上static關鍵字之後瞬間就可以了!