Returning an optional in getters
A practice I’ve used recently and found quite helpful is to wrap the return type of newly created getters inside an Optional.
With the pre-java 8 approach of not wrapping in Optional, we end up with verbose defensive code that contains a lot of nested if (xx != null), or worse, NPEs in production when some getter in the call chain returns a null, which can happen in a lot of scenarios.
As an example:
Having a trip object, we would usually get the traveller name either by using defensive programming, or not doing checks for nulls:
The first option produces code that is clearly too verbose with three nested ifs that hide the business logic and clutter the code.
On the other hand, just forgetting to check for nulls would have the following code throw NPEs in production for some use cases:
The alternative is to wrap the return object inside an Optional, so the getters would become
That way we would have less verbose code that doesn’t throw NPEs.
If it’s okay that the travellerName is null, we’d write something like this:
If we need to throw an exception when we don’t have a travellerName, we’d use the orElseThrow method:
When using Optional, if any of the intermediate calls returns a null value, the following intermediate calls aren’t executed, and only the terminal operation orElse / orElseGet / orElseThrow is executed, preventing an NPE exception while having clear and concise code.