使用Viritin ListDataProvider的网格随机失败

Question

我正在开发一个内部有几个网格的Vaadin Flow（10.0.5）应用程序。所有这些都使用Viritin的ListDataProvider。

引起我头痛的那个通常由200-300行组成（有些情况下最多有1200行）并且有13列。所有列都可以调整大小和排序，第二个标题行包含每列的过滤器，就像应用程序中的每个其他网格一样。

当我滚动网格时，它会生成一个NPE：

java.lang.NullPointerException
at sun.reflect.GeneratedMethodAccessor403.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.__invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.vaadin.flow.data.binder.BeanPropertySet.invokeWrapExceptions(BeanPropertySet.java:516)
at com.vaadin.flow.data.binder.BeanPropertySet.access$600(BeanPropertySet.java:48)
at com.vaadin.flow.data.binder.BeanPropertySet$NestedBeanPropertyDefinition.lambda$getGetter$3ec26976$1(BeanPropertySet.java:200)
at com.vaadin.flow.component.grid.Grid.runPropertyValueGetter(Grid.java:1137)
at com.vaadin.flow.component.grid.Grid.lambda$addColumn$cb98939f$1(Grid.java:1119)
at com.vaadin.flow.component.grid.Grid.lambda$addColumn$c3690ee2$1(Grid.java:923)
at com.vaadin.flow.data.renderer.Renderer$TemplateRendering.lambda$null$2db14883$1(Renderer.java:261)
at com.vaadin.flow.data.provider.CompositeDataGenerator.lambda$generateData$0(CompositeDataGenerator.java:47)
at java.lang.Iterable.forEach(Unknown Source)
at com.vaadin.flow.data.provider.CompositeDataGenerator.generateData(CompositeDataGenerator.java:47)
at com.vaadin.flow.data.provider.CompositeDataGenerator.lambda$generateData$0(CompositeDataGenerator.java:47)
at java.lang.Iterable.forEach(Unknown Source)
at com.vaadin.flow.data.provider.CompositeDataGenerator.generateData(CompositeDataGenerator.java:47)
at com.vaadin.flow.data.provider.DataCommunicator.generateJson(DataCommunicator.java:627)
at java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
at java.util.stream.ReferencePipeline$3$1.accept(Unknown Source)
at java.util.stream.IntPipeline$4$1.accept(Unknown Source)
at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Unknown Source)
at java.util.Spliterator$OfInt.forEachRemaining(Unknown Source)
at java.util.stream.AbstractPipeline.copyInto(Unknown Source)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(Unknown Source)
at java.util.stream.AbstractPipeline.evaluate(Unknown Source)
at java.util.stream.ReferencePipeline.collect(Unknown Source)
at com.vaadin.flow.data.provider.DataCommunicator.getJsonItems(DataCommunicator.java:587)
at com.vaadin.flow.data.provider.DataCommunicator.lambda$collectChangesToSend$2(DataCommunicator.java:550)
at com.vaadin.flow.data.provider.DataCommunicator.applyIfNotEmpty(DataCommunicator.java:601)
at com.vaadin.flow.data.provider.DataCommunicator.withMissing(DataCommunicator.java:595)
at com.vaadin.flow.data.provider.DataCommunicator.collectChangesToSend(DataCommunicator.java:549)
at com.vaadin.flow.data.provider.DataCommunicator.flush(DataCommunicator.java:452)
at com.vaadin.flow.data.provider.DataCommunicator.lambda$requestFlush$2f364bb9$1(DataCommunicator.java:409)
at com.vaadin.flow.internal.StateTree.lambda$runExecutionsBeforeClientResponse$1(StateTree.java:350)
at java.util.ArrayList.forEach(Unknown Source)
at com.vaadin.flow.internal.StateTree.runExecutionsBeforeClientResponse(StateTree.java:347)
at com.vaadin.flow.server.communication.UidlWriter.encodeChanges(UidlWriter.java:334)
at com.vaadin.flow.server.communication.UidlWriter.createUidl(UidlWriter.java:179)
at com.vaadin.flow.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:119)
at com.vaadin.flow.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:91)
at com.vaadin.flow.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1486)
at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:300)

但是其他具有更多列和更多数据的网格（我的一个案例超过2000）导致绝对没有例外。当NPE发生时，我已经检查了要从提供者加载的最后一个数据库对象的id（将网格页面设置为1以确定它是最后一个），它永远不会相同，并且它对于其他对象没有任何特殊之处。网格。

我正在填充网格，主要通过实体的propId设置列，有些是生成的列，就像其他两列的总和一样。

有什么可以导致那些随机异常的想法吗？

提前致谢 ！

Answer 1

在覆盖Grid并将记录器放入runPropertyValueGetter后，似乎NPE是由嵌套在网格主实体中的另一个嵌套实体中的null嵌套实体引起的。

随机效果是由网格渲染的延迟引起的，有时它在故障之前渲染行之前已经失败。