A better way to convert Integer (may be null) to int in Java?

Question

An Integer can be null. I convert an Integer to an int by:

Integer integer = null;
int i;

try {
    i = integer.intValue();
}
catch (NullPointerException e) {
    i = -1;
}

Is there a better way?

you shouldn't use assert in this case cause null is a valid execution path and could indeed happen in production — S. Pauk, Oct 22 '15 at 09:30

score 25 · Answer 1 · answered Jan 18 '19 at 15:20

25

With Java8 the following works, too:

Optional.ofNullable(integer).orElse(-1)

answered Jan 18 '19 at 15:20

This is the correct answer for modern Java as it can be done in one assignment. The ternary expression can't. – Kong Nov 20 '20 at 13:39

Eran · Accepted Answer · 2015-10-22T09:27:39.610

20

Avoiding an exception is always better.

int i = integer != null ? integer.intValue() : -1;

edited Oct 22 '15 at 09:27

answered Oct 22 '15 at 09:27

Eran

3

Darn you and your fast fingers. I was going for the autoboxing way of `int i = integer == null ? 0 : integer;`. – Kayaman Oct 22 '15 at 09:28
1

avoiding C legacy notation could also be considered to be a better way by some ppl – S. Pauk Oct 22 '15 at 09:28
@kocko My original answer (before your edit) without `.intValue()` works fine (Java handles the auto-unboxing). Do you think calling `intValue` explicitly is more efficient? – Eran Oct 22 '15 at 09:31
@Eran, by calling `.intValue()` you avoid the un-boxing and get the primitive value directly. – Konstantin Yovkov Oct 22 '15 at 09:35
4

@kocko `.intValue()` isn't avoiding unboxing; it is _explicitly_ unboxing – khelwood Oct 22 '15 at 09:36
1

@khelwood, I don't agree. If you see the source of `Integer#intValue()` you can see that the method returns the nested `private final int value;`. So, by assigning `integer.intValue()` to an `int` doesn't trigger any boxing/unboxing features of the compiler. However, having `int i = integer;` _will_ actually force the compiler to do unboxing from `Integer` to `int`. That's why I find the explicit call to `.intValue()` a bit more efficient (even there's not much performance difference) and _readable_. – Konstantin Yovkov Oct 22 '15 at 09:37
How does NumberUtils or Guava not already have a method for this? They have defaultValue(primary, fallback) for so many things, but not this. – Snekse Mar 08 '16 at 23:04

score 3 · Answer 3 · answered May 16 '22 at 07:54

3

Java 9 introduce Objects.requireNonNullElse, alternative solution in Java Vanilla (without external library):

Integer integerValue = null;
int intValue = Objects.requireNonNullElse(integerValue, 0);

answered May 16 '22 at 07:54

jpep1

IMO better way than using Optional – xwinus Dec 09 '22 at 12:26
What's the reason? I would like to learn. – Jens.Huehn_at_SlideFab.com Jun 23 '23 at 19:08

score 2 · Answer 4 · edited May 23 '17 at 11:50

2

If you already have guava in your classpath, then I like the answer provided by michaelgulak.

Integer integer = null;
int i = MoreObjects.firstNonNull(integer, -1);

edited May 23 '17 at 11:50

Community

answered Mar 08 '16 at 23:33

Snekse

score 1 · Answer 5 · answered Jun 07 '18 at 16:03

1

Apache Commons Lang 3

Java 8 Stream

answered Jun 07 '18 at 16:03

5 Answers5