Method References & Optional
Learn Java method references and the Optional class.
Method References & Optional is a free Java Academy lesson on CoddyKit. This is lesson 3 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Java Academy learning path, and your progress syncs across the web and the CoddyKit app. The Java Academy course includes 3 lessons in total.
Intro
Method references are a shorthand for lambdas that call an existing method. Optional helps handle missing values safely.
Syntax
Syntax: ClassName::methodName or object::methodName. It replaces a lambda that just calls that method.
Code: method reference
This uses System.out::println as a method reference to print each name.
import java.util.*;public class Main {
public static void main(String[] args) {
List<String> names = Arrays.asList("Ada", "Bob", "Eve");
names.forEach(System.out::println);
}
}
Optional basics
Optional<T> is a container that may or may not hold a value. It helps avoid null pointer errors.
Code: Optional
This wraps a string in Optional and prints it if present.
import java.util.Optional;public class Main {
public static void main(String[] args) {
Optional<String> opt = Optional.of("Hello");
if (opt.isPresent()) {
System.out.println(opt.get());
}
}
}
Code: ifPresent
Optional.ifPresent accepts a lambda to act only if a value exists.
import java.util.Optional;public class Main {
public static void main(String[] args) {
Optional<String> opt = Optional.of("World");
opt.ifPresent(v -> System.out.println("Value: " + v));
}
}
Method reference check
Quick check: Which symbol is used for method references?
Recap
Recap: Method references are shorthand for simple lambdas. Optional stores a value safely and avoids nulls.
Learn Java with an AI tutor — free
Write and run real code in your browser, get instant help from a 24/7 AI tutor, and pick up where you left off on the web or in the app.
- Courses
- 104
- Lessons
- 374
Frequently Asked Questions
Is the “Method References & Optional” lesson free?
Yes — the full text of “Method References & Optional” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Java Academy course, upgrade to CoddyKit PRO. The Java Academy course includes 3 lessons in total.
What will I learn in “Method References & Optional”?
Learn Java method references and the Optional class. You practise Java Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Java Academy?
No prior experience is required. Java Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 3 of 3.
How long does the “Method References & Optional” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Java Academy lesson?
Yes. Every Java Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Lambda Syntax & Scope
- Functional Interfaces
- Method References & Optional