[大数据]structured streaming java.lang.NullPointerException

?问题描述：structured streaming任务报空指针，但报的不是自己的代码，是spark框架的代码，报错日志如下

Caused by: org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 2.0 failed 4 times, most recent failure: Lost task 0.3 in stage 2.0 (TID 39, 10.2.6.21, executor 1): java.lang.NullPointerException

at org.apache.spark.sql.catalyst.expressions.codegen.UnsafeWriter.write(UnsafeWriter.java:110)

at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.writeFields_0_1$(Unknown Source)

at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)

at org.apache.spark.sql.execution.ObjectOperator$.$anonfun$serializeObjectToRow$1(objects.scala:162)

at org.apache.spark.sql.execution.AppendColumnsWithObjectExec.$anonfun$doExecute$15(objects.scala:365)

at scala.collection.Iterator$$anon$10.next(Iterator.scala:459)

at scala.collection.Iterator$$anon$10.next(Iterator.scala:459)

at org.apache.spark.shuffle.sort.BypassMergeSortShuffleWriter.write(BypassMergeSortShuffleWriter.java:156)

at org.apache.spark.shuffle.ShuffleWriteProcessor.write(ShuffleWriteProcessor.scala:59)

at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:99)

at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:52)

at org.apache.spark.scheduler.Task.run(Task.scala:127)

at org.apache.spark.executor.Executor$TaskRunner.$anonfun$run$3(Executor.scala:444)

at org.apache.spark.util.Utils$.tryWithSafeFinally(Utils.scala:1377)

at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:447)

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)

Driver stacktrace:

at org.apache.spark.scheduler.DAGScheduler.failJobAndIndependentStages(DAGScheduler.scala:2023)

at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2(DAGScheduler.scala:1972)

at org.apache.spark.scheduler.DAGScheduler.$anonfun$abortStage$2$adapted(DAGScheduler.scala:1971)

at scala.collection.mutable.ResizableArray.foreach(ResizableArray.scala:62)

at scala.collection.mutable.ResizableArray.foreach$(ResizableArray.scala:55)

at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:49)

at org.apache.spark.scheduler.DAGScheduler.abortStage(DAGScheduler.scala:1971)

at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1(DAGScheduler.scala:950)

at org.apache.spark.scheduler.DAGScheduler.$anonfun$handleTaskSetFailed$1$adapted(DAGScheduler.scala:950)

at scala.Option.foreach(Option.scala:407)

at org.apache.spark.scheduler.DAGScheduler.handleTaskSetFailed(DAGScheduler.scala:950)

at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.doOnReceive(DAGScheduler.scala:2203)

at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:2152)

at org.apache.spark.scheduler.DAGSchedulerEventProcessLoop.onReceive(DAGScheduler.scala:2141)

at org.apache.spark.util.EventLoop$$anon$1.run(EventLoop.scala:49)

at org.apache.spark.scheduler.DAGScheduler.runJob(DAGScheduler.scala:752)

at org.apache.spark.SparkContext.runJob(SparkContext.scala:2093)

at org.apache.spark.sql.execution.datasources.v2.V2TableWriteExec.writeWithV2(WriteToDataSourceV2Exec.scala:382)

... 37 more

?问题分析：spark框架报空指针错误，可能有如下原因：

1.某个Dataset/RDD里的某一条的数据是空（null）的

2.Dataset做groupByKey，类似于Dataset[IntelligentDrivingData]，而IntelligentDrivingData里任何一个字段为null就会报空指针

解决方案：

? 1.map等操作的返回结果不要返回null，可以构造个新的空的对象实例或者数组集合之类的

? ?2.我此次错误的原因就是第2点，把对象的每个字段都附上值就好了