CODEWITHSUNDEEP
javaguava
John Rumpel
John Rumpel

Reputation: 4615

Java/Guava: handle 'null' arguments. Which exception?

It's confusing: We all know the words from Doug Lea: "Null sucks". He is right.

Now I there are some approaches to throw exceptions by using googles guava. But what would be the right way now?

1) throwing an NullPointerException

private void foo(Object arg) {
  Preconditions.checkNotNull(arg, "arg 'null' not accepted");
}

2) or an IllegalArgumentException

private void foo(Object arg) {
  Preconditions.checkArgument(arg!=null, "arg 'null' not accepted");
}

3) or a VerifyException

private void foo(Object arg) {
  Verify.verify(arg!=null, "arg 'null' not accepted");
}

I mean, isn't the first approach obsolete cause we don't have a NullPointer access at this time? And why this new third approach.

Could someone lift the fog?

Upvotes: 1

Views: 1059

Answers (3)

Fritz Duchardt
Fritz Duchardt

Reputation: 11920

"Effective Java" seems quite adamantly in favor of throwing a NullPointerException IllegalArgumentException or NullPointerException for a null parameter?

Upvotes: 1

John B
John B

Reputation: 32969

I agree with Aaron. My two cents is that since in Java 7 Objects.requireNonNull was added and it throws a NullPointerException, that is the way I go. To me it seems like the language developers have weighed in on this issue by doing so.

Upvotes: 4

Aaron Digulla
Aaron Digulla

Reputation: 328724

There is no right way. Some people argue NPE since you passed a null pointer. Plus you can directly use Preconditions.checkNotNull() without any additional checks in code that you have to write (!=null is another 6-10 key presses, after all, plus people have to read more code to understand what you're doing).

Preconditions.checkArgument() makes more sense from an API point of view since the method doesn't want null arguments. Plus you have additional code to write and to read when you're debugging.

Verifify seems too weak for this for me, after reading the documentation.

Upvotes: 3

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