Inheritance & super

Child class extends parent: class Dog extends Animal. Child inherits fields and methods (except private).

Inheritance — extends parent class

Child class extends parent: class Dog extends Animal. Child inherits fields and methods (except private).

Use extends once per class in Java — single inheritance.

Real-life example: Dog inherits from Animal — all dogs eat and sleep (parent), but also bark (child extra).

Basic inheritance

class Animal {
    void eat() {
        System.out.println("Eating...");
    }
}

class Dog extends Animal {
    void bark() {
        System.out.println("Woof!");
    }
}

Dog d = new Dog();
d.eat();
d.bark();

super — call parent constructor or method

super() calls parent constructor — must be first line in child constructor if used.

super.methodName() calls parent version of an overridden method.

Real-life example: super is asking your parent for help — "use Dad's recipe step first, then add my spice."

super keyword

class Person {
    String name;
    Person(String name) { this.name = name; }
}

class Employee extends Person {
    int id;
    Employee(String name, int id) {
        super(name);
        this.id = id;
    }
}