相关疑难解决方法(0)

我在尝试搜索列表中的特定Java对象时遇到了问题.
实际上我得到了我想为另一个Java类工作的搜索功能.现在我尝试了另一个但不是返回结果列表我得到一个NullPointerException.

这就是我的功能:

 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();
    }

这是来自Exception e的strack trace:

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 …