Java Optional - If Else Statements

Question

So after some reading I've seen that

if (optional.isPresent()) {     //do smth } 

is not the preferred way to use Optional (http://www.oracle.com/technetwork/articles/java/java8-optional-2175753.html). But if I have an if-statement like this:

if (optional.isPresent()) {     car = getCar(optional.get()); } else {     car = new Car();     car.setName(carName); } 

Is this the best way to do this or is there a more recommended way?

Answer 1

You can use Optional as following.

Car car = optional.map(id -> getCar(id))             .orElseGet(() -> {                 Car c = new Car();                 c.setName(carName);                 return c;             }); 

Writing with if-else statement is imperative style and it requires the variable car to be declared before if-else block.

Using map in Optional is more functional style. And this approach doesn't need variable declaration beforehand and is recommended way of using Optional.

Answer 2

If you can incorporate the name into the Car constructor, then you can write this:

car = optional.map(id -> getCar(id))               .orElseGet(() -> new Car(carName)); 

If you must call the setter separately from your constructor, you would end up with something like this:

car = optional.map(id -> getCar(id))               .orElseGet(() -> {                   Car c = new Car();                   c.setName(carName);                   return c;               });