Let's assume that we have a method that returns a result based on Optional. If Optional is empty then the method returns a default value. If we consider the previous problem, then a possible solution can be written as follows:

public static final String BOOK_STATUS = "UNKNOWN";
...
// Avoid
public String findStatus() {
  Optional<String> status = ...; // this is prone to be empty

  if (status.isPresent()) {
    return status.get();
  } else {
    return BOOK_STATUS;
  }
}

Well, this is not a bad solution, but is not very elegant. A more concise and elegant solution will rely on the Optional.orElse() method. This method is useful for replacing the isPresent()-get() pair when we want to set or return a default value in case of an empty Optional class. The preceding snippet of code can be rewritten as follows:

public static final String BOOK_STATUS = "UNKNOWN";
...
// Prefer
public String findStatus() {
  Optional<String> status = ...; // this is prone to be empty

  return status.orElse(BOOK_STATUS);
}