- Circle Class
- TV Class
- Point2D Class (Built-in Java Class)
- Date Class (Built-in Java Class)
- Random Class (Built-in Java Class)
- Track the number of objects
- Rectangle Class
- Stock Class
- Use the Date class
- Use the Random class
- Use the GregorianCalendar class
- Build a watch Stopwatch
- Create a bank account
- Fan Class
- Geometry: n-sided polygon class
- Algebra: Quadratic Equations Class
- Algebra: 2×2 Linear Equations Class