Method overriding: deeper practice

1 Learn

Overriding rules: same name, same parameters, compatible return type, and access that is not more restrictive than the parent's.

The @Override annotation asks the compiler to check you really are overriding. It catches typos.

private, static and final methods are not overridden.

Want more detail? Open the full lesson

2 See the Code

Java

class Employee {
    double pay() { return 20000; }
}

class Manager extends Employee {
    @Override
    double pay() { return super.pay() + 15000; }
}

class Intern extends Employee {
    @Override
    double pay() { return 8000; }
}

public class Payroll {
    public static void main(String[] args) {
        Employee[] staff = { new Employee(), new Manager(), new Intern() };
        for (Employee e : staff) {
            System.out.println(e.pay());
        }
    }
}

Each subclass overrides pay() with its own rule.
One loop calls pay() and each object answers in its own way — this is runtime polymorphism.

Output

20000.0
35000.0
8000.0

3 Practice

Create Animal.sound() and override it in Cow and Cat. Store them in an Animal[] and loop.

Try it in your own Java setup or write it in the Practice Notebook.

4 Quick Check

1. What does @Override do?
2. Can a final method be overridden?

Step 5

Answer and check the Quick Check above to unlock this.

Day 24