ofNullable
- Java course
- Advanced
- Lesson 8/82
- 5 min
Learn null safety with Optional.ofNullable.
Null-safe wrapping: ofNullable
Optional.ofNullable(value) works even when the value is null: if it is not null it wraps the value, otherwise it returns an empty Optional. This removes the NullPointerException risk.
Example: Optional.ofNullable(maybeNull). If maybeNull is null the result is Optional.empty(); otherwise it is an Optional holding the value. This method is the safe default for data coming from external sources.
Chaining with ofNullable
ofNullable is usually part of a chain. When the value is present you apply map or filter; when it is not the whole chain silently falls through to an empty Optional.
Example: Optional.ofNullable(input).map(String::toUpperCase).orElse("EMPTY"). If input is null the map is skipped and the result is "EMPTY". This pattern collapses nested null checks into a single line, short and readable.
Practice Wrap a possibly null value
Declare a String maybe = null. Build an Optional<String> with Optional.ofNullable(maybe). Print the result of isPresent() with System.out.println.
Starter code
import java.util.Optional;
// Wrap a possibly null value
// Use Optional.ofNullable
// Print the isPresent resultSample solution
import java.util.Optional;
public class NullableOptional {
public static void main(String[] args) {
String maybe = null;
Optional<String> opt = Optional.ofNullable(maybe);
System.out.println(opt.isPresent());
}
}Expected output
false
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the ofNullable behaviors
| Term | Meaning |
|---|---|
ofNullable(null) |
Optional.empty() |
ofNullable("x") |
Optional[x] |
Optional.of(null) |
NullPointerException |
ofNullable |
null-safe |
2 Which method wraps a null value safely?
- Optional.of
- Optional.empty
- Optional.get
- Optional.ofNullable Correct answer
Explanation: ofNullable returns an empty Optional for null.
3 Complete the ofNullable call
Optional<String> opt = Optional.____(maybeNull);Optional<String> opt = Optional.ofNullable(maybeNull);Explanation: ofNullable is the null-safe wrapper.