java8 / Java8InAction

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Chapter 10 examples,I got error! #29

Open antianchi opened 5 years ago

antianchi commented 5 years ago

Can you run?I can not successfully run the OptionalMain.java.What went wrong,Here public String getCarInsuranceName(Optional<Person> person) { return person.flatMap(Person::getCar) .flatMap(Car::getInsurance) .map(Insurance::getName) .orElse("Unknown"); }

I got NullPointException.The Exception: image

ThisSeanZhang commented 4 years ago

maybe you can modify your Person.java like this

public class Person {

    private Car car;

    public Optional<Car> getCar() {
        return Optional.ofNullable(car);
    }

}