How can I make my program run the validation code in my sub-class rather than the parent class?

As the title suggests, I was wondering if there was a way to make my program execute the validation code in the constructor of my sub-class, instead of the validation code in the constructor in my parent class? Here is a very basic example:

Here I have the constructor of my Teacher class, which throws an exception if age < 18

Teacher(String name, int age) throws InvalidAgeException {
        this.name = name;
        this.age = age;

        if(age < 18){
            throw new InvalidAgeException();
        }

    }
}

And here is the constructor & main method of my Student class, where I would like an exception to be thrown if age > 18, rather than throwing an Exception because age < 18.

    Student(String name, int age) throws InvalidAgeException{
        super(name, age);

        if(age > 18){
            throw new InvalidAgeException();
        }

    }

    public static void main (String[] args) throws InvalidAgeException {
        try {
            Teacher teacher = new Teacher("Matt Jones", 29);
            Student student = new Student ("Liam Price", 16);
        }catch(InvalidAgeException e){
            System.out.println("Invalid age");
        }
    }
}

How could I re-write my code so that different validation checks can be carried out depending on the object being created? This is something I’ve found confusing in a few of my projects.

Thanks

Answer

Your code will check both validations in the sub-class, since you’re using the super() method. But having contradicting validations violates principles of good design, as a subclass be applicable anywhere the super class is applicable.

Instead of writing the validation in the constructor, it’s possible that you could write the validation as another method.