我有以下类型的CombineFn -
CombineFn[KV[ItemVectorKey, java.lang.Iterable[ItemVectorValue]],
java.util.Map[ItemVectorKey, Double],
java.util.Map[ItemVectorKey, Double]]
当我尝试Combine.globally(nc)时，我收到以下错误 -
java.lang.IllegalStateException: Unable to return a default Coder for ComputeNorm/Combine.perKey(NormComputer)/Combine.GroupedValues/ParDo(Anonymous)/ParMultiDo(Anonymous).output [PCollection]. Correct one of the following root causes:
No Coder has been manually specified; you may do so using .setCoder().
Inferring a Coder from the CoderRegistry failed: Cannot provide coder for parameterized type org.apache.beam.sdk.values.KV<K, OutputT>: Unable to provide a Coder for K.
Building a Coder using a registered CoderProvider failed.
See suppressed exceptions for detailed failures.
Using the default output Coder from the producing PTransform failed: PTransform.getOutputCoder called.
at org.apache.beam.sdk.repackaged.com.google.common.base.Preconditions.checkState(Preconditions.java:444)
at org.apache.beam.sdk.values.PCollection.getCoder(PCollection.java:259)
at org.apache.beam.sdk.values.PCollection.finishSpecifying(PCollection.java:107)
at org.apache.beam.sdk.runners.TransformHierarchy.finishSpecifyingInput(TransformHierarchy.java:190)
at org.apache.beam.sdk.Pipeline.applyInternal(Pipeline.java:536)
at org.apache.beam.sdk.Pipeline.applyTransform(Pipeline.java:472)
at org.apache.beam.sdk.values.PCollection.apply(PCollection.java:286)
at org.apache.beam.sdk.transforms.Combine$Globally.expand(Combine.java:1158)
at org.apache.beam.sdk.transforms.Combine$Globally.expand(Combine.java:1025)
at org.apache.beam.sdk.Pipeline.applyInternal(Pipeline.java:537)
at org.apache.beam.sdk.Pipeline.applyTransform(Pipeline.java:491)
at org.apache.beam.sdk.values.PCollection.apply(PCollection.java:299)
at prague.dataflow.logic.recommend.fn.NormComputerTest.runTest(NormComputerTest.scala:67)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.apache.beam.sdk.testing.TestPipeline$1.evaluate(TestPipeline.java:324)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
我让所有编码员都在编码注册表中注册，但我仍然收到此错误。但是，当我用Double替换scala＆＃39; java.lang.Double时，错误消失了。我已经尝试为scala Double注册编码器，但这也没有帮助。
我不想使用java.lang.Double因为它迫使我做了很多scala＆lt; - ＆gt;用于Double的java转换。
除了这个组合之外，我的其他变换（不使用组合）都不会抛出此错误。
我正在使用Apache Beam 2.4.0。