Module 12: Generics and Type Safety
Mini-Project: Generic Queue
Build a small generic queue to practice type-safe design.
Author
Java Learner Editorial Team
Reviewer
Technical review by Java Learner
Last reviewed
2026-04-17
Java version
Java 25 LTS
Learning goals
- Apply generic classes and methods together
- Use type-safe APIs in a reusable structure
- Practice naming and designing type parameters clearly
Project goal: Create a queue-like structure with enqueue, dequeue, and peek methods while keeping the API strongly typed.
What to practice: Generic class declarations, method signatures, and safe use from several concrete types.
Stretch idea: Add a helper method that processes queue items through a generic function.
Success check: The compiler should reject wrong types before the program runs.
Runnable examples
One queue type, many valid element types
QueueBox<String> messages = new QueueBox<>();
QueueBox<Integer> numbers = new QueueBox<>();Expected output
The same structure works for several types while staying type-safe.
Mini exercise
Implement the generic container first, then test it with strings and integers.
Summary
- The project should prove reuse without unsafe casts.
- Good generics improve both safety and readability.
- The compiler should become your ally here.
Next step
Next comes streams, where generics and collections work together for cleaner data processing.
Sources used