<分区>
我在尝试搜索列表中的特定 Java 对象时遇到问题。
实际上我得到了我想要为另一个 Java 类工作的搜索功能。现在我尝试了另一个结果，但没有返回结果列表，而是得到了 NullPointerException。
这是我的函数的样子:
public static List<Customer> searchByEverything(String keyword){
List<Customer> customerList = find.all(); //Using java Ebean
System.out.println(keyword); //Check if keyword is not empty
System.out.println(customerList); //Check if list is not empty
Predicate<Customer> customerPredicate = u -> u.name.toLowerCase().contains(keyword.toLowerCase());
try{
return customerList.stream().filter(customerPredicate).collect(Collectors.toList());
}catch (Exception e){
e.printStackTrace();
}
这是异常 e 的 strack 跟踪:
java.lang.NullPointerException
at models.Customer.lambda$searchByEverything$2(Customer.java:174)
at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:174)
at java.util.ArrayList$Itr.forEachRemaining(ArrayList.java:891)
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
at models.Customer.searchByEverything(Customer.java:179)
at controllers.Application.searchCustomers(Application.java:262)
at router.Routes$$anonfun$routes$1$$anonfun$applyOrElse$17$$anonfun$apply$17.apply(Routes.scala:479)
at router.Routes$$anonfun$routes$1$$anonfun$applyOrElse$17$$anonfun$apply$17.apply(Routes.scala:479)
at play.core.routing.HandlerInvokerFactory$$anon$4.resultCall(HandlerInvoker.scala:157)
at play.core.routing.HandlerInvokerFactory$$anon$4.resultCall(HandlerInvoker.scala:156)
at play.core.routing.HandlerInvokerFactory$JavaActionInvokerFactory$$anon$14$$anon$3$$anon$1.invocation(HandlerInvoker.scala:136)
at play.core.j.JavaAction$$anon$1.call(JavaAction.scala:73)
at play.http.HttpRequestHandler$1.call(HttpRequestHandler.java:54)
at play.mvc.Security$AuthenticatedAction.call(Security.java:53)
at play.core.j.JavaAction$$anonfun$7.apply(JavaAction.scala:108)
at play.core.j.JavaAction$$anonfun$7.apply(JavaAction.scala:108)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.liftedTree1$1(Future.scala:24)
at scala.concurrent.impl.Future$PromiseCompletingRunnable.run(Future.scala:24)
at play.core.j.HttpExecutionContext$$anon$2.run(HttpExecutionContext.scala:56)
at play.api.libs.iteratee.Execution$trampoline$.execute(Execution.scala:70)
at play.core.j.HttpExecutionContext.execute(HttpExecutionContext.scala:48)
at scala.concurrent.impl.Future$.apply(Future.scala:31)
at scala.concurrent.Future$.apply(Future.scala:492)
at play.core.j.JavaAction.apply(JavaAction.scala:108)
at play.api.mvc.Action$$anonfun$apply$2$$anonfun$apply$5$$anonfun$apply$6.apply(Action.scala:112)
at play.api.mvc.Action$$anonfun$apply$2$$anonfun$apply$5$$anonfun$apply$6.apply(Action.scala:112)
at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
at play.api.mvc.Action$$anonfun$apply$2$$anonfun$apply$5.apply(Action.scala:111)
at play.api.mvc.Action$$anonfun$apply$2$$anonfun$apply$5.apply(Action.scala:110)
at scala.Option.map(Option.scala:146)
at play.api.mvc.Action$$anonfun$apply$2.apply(Action.scala:110)
at play.api.mvc.Action$$anonfun$apply$2.apply(Action.scala:103)
at scala.concurrent.Future$$anonfun$flatMap$1.apply(Future.scala:251)
at scala.concurrent.Future$$anonfun$flatMap$1.apply(Future.scala:249)
at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)
at akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:55)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply$mcV$sp(BatchingExecutor.scala:91)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
at akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:72)
at akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:90)
at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:39)
at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:415)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
正如我所说，我对不同的类实现了完全相同的搜索，而且效果非常好。 customerList 和 keyword 都不为空。在我的 customerList 中搜索与在另一个列表中搜索的唯一区别是它有大约 4500 个对象，每个对象有大约 50 个属性。也许这就是问题所在？
提前致谢!