CODEWITHSUNDEEP
javajava-8
Ram
Ram

Reputation: 731

How effectively we can code null checks Java 8

Little new to Java 8 style;

How effectively, we can code for the below statement by including all the null checks usin Java 8 API

search.getResource()
                        .getResults().get(0).getCustomer().getPhoneNumber()

I tried like following: (Looks little weird to me with Optional everywhere)

List<Result> results = search.getResource().getResults();

                Optional<Result> optionalResult =  Optional.of(results).orElse(new ArrayList<>()).stream().findFirst();
                if(optionalResult.isPresent() && Optional.of(optionalResult.get().getCustomer()).isPresent()) {
                    Source source = Optional.of(optionalResult.get().getCustomer()).get();
                    Optional<List<Customer>> customers = Optional.of(source.getCustomers());
                    if(customers.isPresent() && customers.get().stream().findFirst().isPresent() &&
                            Optional.of(customers.get().stream().findFirst().get().getPhoneNumber()).isPresent())
                        dest.setNumber(Integer.parseInt(customers.get().stream().findFirst().get().getPhoneNumber())));
                }

Could you please suggest me a better way of doing. Thanks!

Upvotes: 0

Views: 89

Answers (2)

Timothy Truckle
Timothy Truckle

Reputation: 15622

OT: Why don't you simply code null safe?

Coding null safe means that you never explicitly retun a (literal) null from a method or pass one in as a parameter. Furthermore you always do you null checks on local variables before you pass them around or return them.
On Map collections you use getOrDefault or computeIfAbsent to replace the null returned for missing keys with a Null Equivalent Constant of the expected type.

Usually passing null back and forth is a in band signal for an error condition which Java has exceptions for.

And no: passing around Optional is not a solution, but another incarnation of the problem. Optional is an elegant way to deal with variables than may contain null within a method.
Don't let it escape...

Upvotes: 2

enzo
enzo

Reputation: 11496

You can use the map method of Optional class:

final Optional<String> optional = Optional.ofNullable(search.getResource())
    .map(resource -> resource.getResults())
    .map(results -> results.size() > 0 ? results.get(0) : null)
    .map(result -> result.getCustomer())
    .map(customer -> customer.getPhoneNumber());

optional.ifPresent(phoneNumber -> {
    System.out.println(phoneNumber);
});

Upvotes: 7

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