Java Coding Problems

245. Transforming values via Map() and flatMap()

The Optional.map() and flatMap() methods are convenient for transforming an Optional value.

The map() method applies the function argument to the value, then returns the result wrapped in an Optional object. The flatMap() method applies the function argument to the value and then returns the result directly.

Let's assume that we have Optional<String>, and we want to transform this String from lowercase into uppercase. An uninspired solution can be written as follows:

Optional<String> lowername = ...; // may be empty as well// AvoidOptional<String> uppername;if (lowername.isPresent()) {  uppername = Optional.of(lowername.get().toUpperCase());} else {  uppername = Optional.empty();}

A more inspired ...