Module 14: Enums and Annotations

Built-in Annotations You Should Use

Use the built-in annotations that improve safety, clarity, and compiler feedback.

Author

Java Learner Editorial Team

Reviewer

Technical review by Java Learner

Last reviewed

2026-04-17

Java version

Java 25 LTS

How this lesson was prepared: AI-assisted draft, manually edited for clarity, and checked against current Java documentation and runnable examples.

Learning goals

Know what the most common built-in annotations actually do
Use `@Override` everywhere it belongs
Avoid lazy overuse of `@SuppressWarnings`

Annotations add metadata to code: They communicate meaning to the compiler, tools, and other developers.

@Override is the most practical one to use constantly: It prevents silent mistakes in inheritance and interface implementations.

@Deprecated warns users away from old APIs, and @SuppressWarnings should be narrow and justified: Do not use it as a broom for messy code.

Intermediate habit: If an annotation improves correctness or clarity, use it. If it hides a real problem, step back first.

Runnable examples

Override with compiler protection

class Animal {
    public void speak() {}
}

class Dog extends Animal {
    @Override
    public void speak() {
        System.out.println("Woof");
    }
}

Expected output

`@Override` ensures the compiler checks that `speak()` really matches a parent method.

Mini exercise

Find one overridden method in your code and add `@Override` if it is missing.

Summary

Annotations communicate intent and metadata.
`@Override` is especially valuable for correctness.
`@SuppressWarnings` should stay narrow and deliberate.

Next step

Next, create your own annotations and choose the right retention policy.

Sources used

Built-in Annotations You Should Use

Override with compiler protection

Why is `@Override` so useful?