Should Optional.ofNullable() be used for null check?

Question

Which null-check is preferable?

Optional.ofNullable(port).ifPresent(settings::setPort);

or

if (port != null) {
   settings.         


        

Answer 1

In Java, an Optional value is a fusion of a bit that indicates presence or absence, with a value of an arbitrary reference type T or a primitive int, long, or double.

Fusing these is especially useful when returning a value from a method, as methods have only a single return value. It's often necessary to use a special value such as null in the case of reference types, or -1 in the case of int, as a sentinel to indicate the "no-value" case. Using Optional as a return value avoids the problem of the caller accidentally misusing the sentinel value as the real return value.

Given this, line of code such as

Optional.ofNullable(port).ifPresent(settings::setPort);

is strange in that it fuses a value with the present/absent bit in the first part of the line and then immediately separates them in the second part of the line. This adds complexity to what is ultimately a fairly simple task: checking whether port is non-null and conditionally performing some action. The alternative code snippet:

if (port != null) {
    settings.setPort(port);
}

expresses quite clearly exactly what it does.

It's true that the if-statement takes more vertical space than the Optional chain. The Optional chain is denser, but it's also harder to understand: a poor tradeoff.

Answer 2

It is dependent on several factors when to use this. If port is a property within the class, probably using Optional is a bit overkill. (and don't useOptionals as property as they are not serializbie)

I think Optionals are great when for example writing a library.

public Optional<Integer> getPort()

Is much more descriptive for other developers then

// Returns null if not set
public Integer getPort()

Answer 3

Although, the snippet you have posted in the question is just a simple way to avoid the ugly null-check, yet is valid, correct and null-safe. Follow your personal preference in this case.

The real power of Optional are the following methods:

• Optional::filter(Predicate<? super T> predicate) which applies a filter on a present value.
• Optional::map(Function<? super T,? extends U> mapper) which applies a mapping function on a present value.

As example, let's say you want to get another value from port to add to the list and avoid the NPE if port is null:

Optional.ofNullable(port).map(port::getSomeValue).ifPresent(settings::setPort);

Moreover, please, avoid the following meaningless substitution of null-check I see often:

if (Optional.ofNullable(port).isPresent()) {
    settings.setPort(port);
}