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?

Solution 1

Avoiding an exception is always better.

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

Solution 2

With Java8 the following works, too:

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

Solution 3

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);

Solution 4

Apache Commons Lang 3

ObjectUtils.firstNonNull(T...)

Java 8 Stream

Stream.of(T...).filter(Objects::nonNull).findFirst().orElse(null)

Taken From: https://stackoverflow.com/a/18741740/6620565

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Comments

[S. Pauk]

you shouldn't use assert in this case cause null is a valid execution path and could indeed happen in production

[Kayaman]

Darn you and your fast fingers. I was going for the autoboxing way of int i = integer == null ? 0 : integer;.

[S. Pauk]

avoiding C legacy notation could also be considered to be a better way by some ppl

[Eran]

@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?

[Konstantin Yovkov]

@Eran, by calling .intValue() you avoid the un-boxing and get the primitive value directly.

[khelwood]

@kocko .intValue() isn't avoiding unboxing; it is explicitly unboxing

[Konstantin Yovkov]

@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.

[Snekse]

How does NumberUtils or Guava not already have a method for this? They have defaultValue(primary, fallback) for so many things, but not this.

[Kong]

This is the correct answer for modern Java as it can be done in one assignment. The ternary expression can't.