NULL safe object checking in JAVA 8

Question

So i want to do a null safe check on a value contained within a value.

So I have 3 objects contained within each other:

Person has a clothes object which has a country object which has a capital

So a person may not have clothes so a check like this throws a null pointer:

if (person.getClothes.getCountry.getCapital)

How would I make a statement like this just return false if any of the objects on the path are null?

I also don't want to do it this way. (A one-liner in Java-8 if possible.

if (person !=null) {
    if (person.getClothes != null) {
        if (person.getClothes.getCountry !=null) {
            etc....
        }
    }
}

Answer 1

You can chain all of those calls via Optional::map. I sort of find this easier to read than if/else, but it might be just me

Optional.ofNullable(person.getClothes())
        .map(Clothes::getCountry)
        .map(Country::getCapital)
        .ifPresent(...)

Answer 2

These "cascade" null-checks are really paranoid and defensive programming. I'd start with a question, isn't better to make it fail fast or validate the input right before it's store into such a data structure?

Now to the question. As you have used nested the null-check, you can do the similar with Optional<T> and a method Optional::map which allows you to get a better control:

Optional.ofNullable(person.getClothes())
        .map(clothes -> clothes.getCountry())
        .map(country -> country.getCapital())
        .orElse(..)                               // or throw an exception.. or use ifPresent(...)