A try-catch scenario - correct to use checked or not

Question

I am looking at a code base where the domain model consists of many nested member variables.

Consider this scenario

private static String getSomeStringRepresentation(A input) {
    String result = "";
    try {
         result = input.getTypeA().getTypeAInfo().get(0).getRepresentation();
    } catch (NullPointerException e) {
        Logger.logDebug(e.getMessage());
    }
    return result;
}

In this call chain, any method call can result in a NullPointerException. Is it correct to handle it with a catch clause in this case? Is this a case where "it is possible to handle the exception" ?

Edit

The case of checking for null four times is really ugly. Don't you consider catching the NPE is justified in this case?

The problem here is calling some method on a object that possibly could be null.

If all methods could throw an NullPointerException, why would it be incorrect not to use a try-catch case? — akluth, Apr 26 '13 at 07:59

score 4 · Accepted Answer · edited May 23 '17 at 11:43

4

Why don't you check for null rather than putting a catch block? Catching NullPointerException isn't considered good practice.

If catching null pointer exception is not a good practice, is catching exception a good one?

also

Is Catching a Null Pointer Exception a Code Smell?

edited May 23 '17 at 11:43

Community

1
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answered Apr 26 '13 at 07:59

gurvinder372

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Basically I don't think it's pretty to do N different != null checks :). – H.Rabiee Apr 26 '13 at 10:26
@hajder It might not be pretty, but if you are using a third-party library, then its better to use a null check explicitly – gurvinder372 Apr 26 '13 at 10:31

score 2 · Answer 2 · edited May 23 '17 at 11:43

2

Catching a NullPointerException is not a good practice without a serious reason: Rather check for null object like this:

private static String getSomeStringRepresentation(A input) {
    String result = "";
    try {
         if(input != null && input.getTypeA() != null && input.getTypeA().getTypeAInfo() != null && getTypeAInfo().get(0) != null){
              result = input.getTypeA().getTypeAInfo().get(0).getRepresentation();     
         }

    } catch (NullPointerException e) {
        Logger.logDebug(e.getMessage());
    }
    return result;
}

Here is a possible duplicate on the subject.

edited May 23 '17 at 11:43

Community

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answered Apr 26 '13 at 08:02

javadev

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Sorry if I was a bit unclear, none of the methods actually throw a NPE. What could cause an exception is if a method is called on a null object. – H.Rabiee Apr 26 '13 at 10:28
A NullPointerException for sure. – javadev Apr 26 '13 at 12:59

score 1 · Answer 3 · answered Apr 26 '13 at 08:03

1

NPEs are just an error in the code and should therefore not be catched - they should be fixed.

answered Apr 26 '13 at 08:03

LionC

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score 0 · Answer 4 · answered Apr 26 '13 at 07:59

0

NullPointerException indicates a programming error, catching it is wrong. Instead of catching it fix bugs in your program.

answered Apr 26 '13 at 07:59

Evgeniy Dorofeev

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A try-catch scenario - correct to use checked or not

Edit

4 Answers4