How to convert Optional<Object> to Optional [closed]

Answer 1

Use:

String value = Optional.ofNullable(getObjectOrNullIfNotAvailable()).map(Object::toString).orElse(null);

Otherwise, you can check if an Object is null and return in that case a String with "null" inside with String.valueOf(Object obj) or Objects.toString(Object obj). Eg.

  String value = Objects.toString(getObjectOrNullIfNotAvailable())

Answer 2

You can use map followed by orElse no need to separate them like so :

String value = Optional.ofNullable(a)
        .map(Object::toString)
        .orElse(null);

Answer 3

Creating an Optional out of the return value of a method seems a bit awkward. Rather let your getObjectOrNullIfNotAvailable() method return an Optional in the first place. Then use the map operator to convert it in to a string. Here's how it looks.

Optional<Object> oa = someOptionalReturningMethod();
String value = oa.map(Object::toString).orElse(null);

For some reason if you can't change the return value of the method to an Optional, just leave the imperative solution using the ternary operator. Nothing wrong with that.

String value = a==null ? null : a.toString();