Java – how to prevent the function passed to optional orelse from being executed when optional is not empty?

If I call a function from orelse, the function will be executed even if optional is not empty Is there any way to restrict the execution of functions only when option is empty?

Optional.ofNullable(someValue).orElse(someFunction());

Solution

Somefunction () is executed because it is a parameter passed to the method, which is evaluated before the method is executed To avoid execution, you should pass somefunction () in the supplier instance

Use orelseget instead of orelse:

Optional.ofNullable(someValue).orElseGet(SomeClass::someFunction);

or

Optional.ofNullable(someValue).orElseGet(()->someFunction());