Remove embedded null check with 'Optional' in Java 8

Question

I replaced the following code:

if (status.getPlace() == null) {
    row.set("CountryCode", "Unknown");
    row.set("Country", "Unknown");
} else {
    if (status.getPlace().getCountryCode() == null) {
        row.set("CountryCode", "Unknown");
    } else {
        row.set("CountryCode", status.getPlace().getCountryCode());
    }
    if (status.getPlace().getCountry() == null) {
        row.set("Country", "Unknown");
    } else {
        row.set("Country", status.getPlace().getCountry());
    }
}

With this:

String countryCode = Optional.ofNullable(status.getPlace())
        .filter(p -> p.getCountryCode() != null)
        .map(Place::getCountryCode)
        .orElse("Unknown");
row.set("CountryCode", countryCode);

String country = Optional.ofNullable(status.getPlace())
        .filter(p -> p.getCountry() != null)
        .map(Place::getCountry)
        .orElse("Unknown");
row.set("Country", country);

It's working as expected but somehow I think I can do better. I still have a 'null' check in there.

.filter(p -> p.getCountryCode() != null)

Is there a way to avoid the above null check?

There is a way if you make getCountryCode return Optional, then you can simply use flatMap — FilipRistic
– FilipRistic, Commented Jul 19, 2018 at 16:25

Pankaj Singhal · Accepted Answer · 2018-07-19 16:35:25Z

18

You don't need the null check - .filter(p -> p.getCountry() != null). Remove this and your code should work fine.

Optional.map() returns an Optional instance itself. So no need to apply the null check.

edited Jul 19, 2018 at 16:35

answered Jul 19, 2018 at 16:28

Pankaj Singhal

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1 Comment

Holger Over a year ago

Don’t know who downvoted, but perhaps it’s worth to link to the specification and citing the relevant sentence: “If a value is present, apply the provided mapping function to it, and if the result is non-null, return an Optional describing the result. Otherwise return an empty Optional.”. Maybe that’ll convince the disbelievers.

Ousmane D. · Accepted Answer · 2018-07-19 16:36:29Z

9

You don’t need the filter operation at all. if the call to Place::getCountryCode or Place::getCountry returns null then an empty optional is returned which means the orElse method will be called to retrieve the alternative value.

answered Jul 19, 2018 at 16:36

Ousmane D.

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