This particular NPE can be avoided if the comparison order is reversed; namely, use .equals on a guaranteed non-null object. All elements inside of an array are initialized to their common initial value ; for any type of object array, that means that all elements are null .

2018年10月29日 · Here are some restrictions: 1) errorList - cannot be null here so a call to .stream() is safe - when it's empty it will just return false 2) getErrorSegment() and getErrorDetails() can both be nulls tha's why I'm using filter like that to make sure none of them is null 3) getErrorCode() can be null but it will never throw NPE because it will ...

Usually it's good either to check if variable is null or catch NPE and trow more appropriate reason. For example if a method getCar() returned null you may catch NPE on trying to call some method of the car, or check if the car is null and throw RuntimeException(but only if the situation is really exceptionable). Thus you make errors more ...

2016年7月4日 · The second row of myMethod(String someId, SomeHeaderParams someHeaderParams) in MyController class:. There is an invocation of the method myClientService.getHeaderParams(SomeHeaderParams): I don't see any mock configuration for that invocation, so it should return null, and when the buildRequest(String, Map, Map) method …

When you do that, n2.next.next may be null, so n2 will be null after the assignment. When the loop repeats and it checks if n2.next is not null, it throws the NPE because it can't get to next since n2 is already null. You want to do something like what Alex posted instead.

2015年3月31日 · You should have a stacktrace if this is a NPE as you state. The reason for the program not crashing is you may be handling and "swallowing" your exceptions. Consider removing catch blocks or re-throwing a RuntimeException wrapping the root cause to make you application crash - then address the cause of the crash!

2017年8月25日 · I used to use lots of @NotNull/@Nullable annotations to enable IDE to help me find out potential NPE at compile time. However, my new team doesn't allow any use of @NotNull/@Nullable annotations, and nor are custom annotations like those allowed. As a result, I become much more likely to write bugs caused by NPE than before.

2015年10月14日 · If you're using Scala and you try to create an any matcher on a value class, you'll get an unhelpful NPE. So given case class ValueClass(value: Int) extends AnyVal , what you want to do is ValueClass(anyInt) instead of any[ValueClass]

2019年8月8日 · The third option is for NPE-lovers: the not-null assertion operator (!!) converts any value to a non-null type and throws an exception if the value is null. We can write b!!, and this will return a non-null value of b (e.g., a String in our example) or throw an NPE if …

2017年4月11日 · Because of the cases where it might be absent due to a condition or something (try/catch? etc.)... I think the stream methods findFirst or findAny are good examples for it: if you filter a stream it could be that nothing matches... in that case findFirst/findAny would return an empty Optional, which I personally prefer instead of null (also due to the convenience methods …