Optional

java.lang.Object
    java.util.Optional<T>

• Is a container object which may or may not contain a non-null value.

• Is a value-based class; use of identity-sensitive operations may have unpredictable results and should be avoided.

• Primarily intended for use as a method return type where there is a clear need to represent “no result”.

class Person {
    Optional<Bike> bike;
}

class Bike {
    Optional<Insurance> insurance;
}

class Insurance {
    LocalDate validTill;
}

Creating Optional objects

Type	How
Empty Optional	Optional.empty()
From non-null value	Optional.of(bike)
From may be null value	Optional.ofNullable(bike)

Using map on Optional

Before

LocalDate validTill = null;
if (insurance != null) {
    validTill = insurance.getValidTill();
}

After

Optional<Insurance> insurance = Optional.ofNullable(insurance);
Optional<LocalDate> validTille = insurance.map(Insurance::getValidTill);

Chaining Optional objects with flatMap