Nested objects null checking

Question

I know many ways how to check on nested objects for a NullPointerException, as for Java 8 the simplest is to apply the Optional. or t

Answer 1

As you mentioned yourself in the question, use Optional, but it's more lenghty.

excel.setCell(name1, Optional.of(contract).map(Contract::getContactInfo).map(ContactInfo::getPosition).orElse(null));
excel.setCell(name2, Optional.of(contract).map(Contract::getEntitledPerson).map(Person::getEmail).orElse(null));

Which is more easily read when formatted like this:

excel.setCell(name1, Optional.of(contract)
                             .map(Contract::getContactInfo)
                             .map(ContactInfo::getPosition)
                             .orElse(null));
excel.setCell(name2, Optional.of(contract)
                             .map(Contract::getEntitledPerson)
                             .map(Person::getEmail)
                             .orElse(null));

If your goal is smallest code, you could just catch the NullPointerException. It's a bit of a hack, in my opinion, but it'll do the trick.

First, a helper method:

public static <T> T nullGuard(Supplier<T> supplier) {
    try {
        return supplier.get();
    } catch (@SuppressWarnings("unused") NullPointerException ignored) {
        return null;
    }
}

Then you wrapper the expression in question:

excel.setCell(name1, nullGuard(() -> contract.getContactInfo().getPosition()));
excel.setCell(name2, nullGuard(() -> contract.getEntitledPerson().getEmail()));