optionalorElseGet

optionalorElseGet is a method in the Java programming language, part of the Optional class introduced in Java 8. It provides a way to retrieve the value contained within an Optional object if it is present, or generate a value using a supplier function if it is absent. This method is commonly used to handle optional values more gracefully, avoiding the need for explicit null checks.

The signature of optionalorElseGet is as follows: Optional.orElseGet(Supplier<? extends T> other). When invoked, if the Optional contains a non-null value, that value is returned. If the Optional is empty, the Supplier provided as the argument is executed to generate a default or fallback value. This approach allows for lazy evaluation of the alternative value, meaning the supplier function is only invoked if necessary, which can improve performance especially when generating the fallback value is resource-intensive.

For example, suppose an application attempts to retrieve a user's address from a database. If the address is not present, a default address might be provided. Using optionalorElseGet, this can be achieved succinctly: optionalAddress.orElseGet(() -> fetchDefaultAddress()). Here, fetchDefaultAddress() is only called if optionalAddress is empty.

This method complements other Optional methods like orElse, which also provides a fallback value but evaluates it eagerly, regardless of whether the Optional contains a value. Using optionalorElseGet promotes more efficient code, particularly when the fallback logic involves costly operations.

In summary, optionalorElseGet is a useful construct in Java for handling optional values, enabling developers to specify fallback values through supplier functions that are invoked only when necessary, thereby supporting cleaner and more efficient code.