The super keyword

class Person {
    String name;
    int age;

    Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

class Student extends Person {
    String college;

    Student(String name, int age, String college) {
        super(name, age);
        this.college = college;
    }
}

public class Main {
    public static void main(String[] args) {
        Student s = new Student("Riya", 20, "COEP Pune");
        System.out.println(s.name + ", " + s.age + ", " + s.college);
    }
}

class Grandparent {
    Grandparent() {
        System.out.println("Grandparent constructor");
    }
}

class Parent extends Grandparent {
    Parent() {
        System.out.println("Parent constructor");
    }
}

class Child extends Parent {
    Child() {
        System.out.println("Child constructor");
    }
}

public class Main {
    public static void main(String[] args) {
        new Child();
    }
}

class Vehicle {
    String regNo;
    int wheels;

    void details() {
        System.out.println("Reg no: " + regNo);
        System.out.println("Wheels: " + wheels);
    }
}

class Car extends Vehicle {
    int seats;

    @Override
    void details() {
        super.details();
        System.out.println("Seats: " + seats);
    }
}

public class Main {
    public static void main(String[] args) {
        Car c = new Car();
        c.regNo = "DL-3C-4567";
        c.wheels = 4;
        c.seats = 5;
        c.details();
    }
}

class Shop {
    String city = "Mumbai";
}

class Branch extends Shop {
    String city = "Nashik";

    void show() {
        System.out.println("Branch city: " + city);
        System.out.println("Head office city: " + super.city);
    }
}

public class Main {
    public static void main(String[] args) {
        new Branch().show();
    }
}

class Course {
    String title;
    int seats;

    Course(String title, int seats) {
        this.title = title;
        this.seats = seats;
        System.out.println("Course(" + title + ", " + seats + ")");
    }
}

class OnlineCourse extends Course {
    String platform;

    OnlineCourse(String title) {
        this(title, 500, "Web");
        System.out.println("OnlineCourse(title) done");
    }

    OnlineCourse(String title, int seats, String platform) {
        super(title, seats);
        this.platform = platform;
        System.out.println("OnlineCourse(title, seats, platform) done");
    }
}

public class Main {
    public static void main(String[] args) {
        OnlineCourse a = new OnlineCourse("Core Java");
        System.out.println(a.title + " | " + a.seats + " | " + a.platform);
        OnlineCourse b = new OnlineCourse("Spring Boot", 120, "App");
        System.out.println(b.title + " | " + b.seats + " | " + b.platform);
    }
}

class Product {
    String name;

    Product(String name) {
        this.name = name;
    }
}

class Gift extends Product {
    String message;

    Gift(String message) {
        super("Gift box");          // the fix: call the constructor that exists
        this.message = message;
    }
}

public class Main {
    public static void main(String[] args) {
        Gift g = new Gift("Happy Diwali!");
        System.out.println(g.name + ": " + g.message);
    }
}

class Basic {
    String benefits() {
        return "free delivery";
    }
}

class Silver extends Basic {
    @Override
    String benefits() {
        return super.benefits() + ", 5% cashback";
    }
}

class Gold extends Silver {
    @Override
    String benefits() {
        return super.benefits() + ", priority support";
    }
}

public class Main {
    public static void main(String[] args) {
        System.out.println("Gold: " + new Gold().benefits());
        System.out.println("Silver: " + new Silver().benefits());
    }
}

class Account {
    private final String no;
    protected final double amount;

    Account(String no, double amount) {
        if (amount < 1000) throw new IllegalArgumentException("Minimum Rs 1000");
        this.no = no;
        this.amount = amount;
    }

    String summary() {
        return no + " | principal Rs " + amount;
    }
}

class FixedDeposit extends Account {
    private final int months;
    private final double ratePercent;

    FixedDeposit(String no, double amount, int months, double ratePercent) {
        super(no, amount);
        this.months = months;
        this.ratePercent = ratePercent;
    }

    double maturity() {
        return amount + amount * ratePercent / 100 * months / 12;
    }

    @Override
    String summary() {
        return super.summary() + " | " + months + " months @ " + ratePercent + "% | maturity Rs " + maturity();
    }
}

public class Main {
    public static void main(String[] args) {
        FixedDeposit fd = new FixedDeposit("FD-501", 100000, 12, 7);
        System.out.println(fd.summary());
    }
}

class Delivery {
    protected final int km;

    Delivery(int km) {
        this.km = km;
    }

    double charge() {
        return 40 + 8 * km;
    }
}

class ExpressDelivery extends Delivery {
    ExpressDelivery(int km) {
        super(km);
    }

    @Override
    double charge() {
        return super.charge() * 1.5;
    }
}

class NightExpress extends ExpressDelivery {
    NightExpress(int km) {
        super(km);
    }

    @Override
    double charge() {
        return super.charge() + 100;
    }
}

public class Main {
    public static void main(String[] args) {
        System.out.println("Normal: Rs " + new Delivery(12).charge());
        System.out.println("Express: Rs " + new ExpressDelivery(12).charge());
        System.out.println("Night express: Rs " + new NightExpress(12).charge());
    }
}

class Employee {
    protected final String id;
    protected final double monthlyPay;

    Employee(String id, double monthlyPay) {
        this.id = id;
        this.monthlyPay = monthlyPay;
        System.out.println("Joined: " + id + " at Rs " + monthlyPay);
    }
}

class Intern extends Employee {
    private static final double CAP = 25000;

    Intern(String id, double stipend) {
        super(id, Math.min(stipend, CAP));
    }

    double pay() {
        return monthlyPay;
    }
}

public class Main {
    public static void main(String[] args) {
        Employee e = new Employee("E10", 55000);
        Intern i = new Intern("I07", 30000);
        System.out.println(e.id + " pay: " + e.monthlyPay);
        System.out.println(i.id + " pay: " + i.pay());
    }
}