Inheritance

The capability of a class to derive properties and characteristics from another class

Creating Classes and Subclasses

For the example not using inheritance for each of the three classes we have to rewrite the three methods
By creating a superclass vehicle which is extended by the three subclasses we reduce risk of error and redundancy and simplifies our code

public class Vehicle {
    public int fuelamount;
    public int capacity;
    public boolean applyBrakes;

    public Vehicle (int fuelamount, int capacity, boolean applyBrakes) {
        this.fuelamount;
        this.capacity;
        this.applyBrakes;
    }
}
public class Bus extends Vehicle {
}
public class Car extends Vehicle {
}
public class Truck extends Vehicle {
}

Writing constructors for subclasses

Allows reusing the code and adding attributes if needed in every subclass.
A subclass can also become a super class by extending it again in another subclass.
Same goes for a constructor in which, the keyword “super” is used to call the super class constructor and can add additional attributes for personalization.

Creating References using Inheritance Hierarchies

Superclasses and subclasses are generally organized into a single root tree structure called an inheritance hierarchy. In this type of hierarchy, attributes and methods that are associated with a specific class are inherited by lower levels of the hierarchy.
When working with a hierarchy of subclasses and superclasses, the object type and reference type can be different when instantiating an object variable.
Example: Fruit fruit1 = new Apple(); In this case, the reference type is declared with the superclass, while the object type is declared with the subclass.

Object superclass

The object superclass is located at the top of every class hierarchy. This means all of the other classes in a hierarchy can use the attributes and methods of the object superclass through inheritance. It is a part of the built-in java.lang package.
The object superclass contains common, useful methods such as equals() and toString(). The equals() method compares two objects; it is often used to check for equality between 2 String objects, comparing each character of both strings to check if they are the same.
The toString() method returns a String representation of a given object.

Part 1

Create a world cup superclass with properties of your choice and subclasses for five teams which inherits those properties
Write a constructor for one of those subclasses

public class WorldCup {
    protected String country;
    protected String bestplayer;

    public WorldCup (String country, String bestplayer) {
        this.country = country;
        this.bestplayer = bestplayer;
    }
    public String getCountry(){
        return country;
    }

    public String getBestPlayer(){
        return bestplayer;
    }

    @Override
    public String toString() {
         return "WorldCup (country: " + country + ", bestplayer: " + bestplayer + ")";
    }
    
    public static void main(String[] args) {
        WorldCup Qatar = new WorldCup("Qatar", "who knows");
        System.out.println(Qatar.toString());
    }
}
public class Morocco extends WorldCup {
    private int goalsscored;
    private int goalsagainst;

    public Morocco (String country, String bestplayer, int goalsscored, int goalsagainst){
        super(country, bestplayer);
        this.goalsscored = goalsscored;
        this.goalsagainst = goalsagainst;
    }
    public int getgoalsscored() {
        return goalsscored;
    }
    public int getgoalsagainst() {
        return goalsagainst;
    }

    @Override
    public String toString() {
         return "WorldCup (country: " + country + ", bestplayer: " + bestplayer + ", Goals Scored: " + goalsscored + ", Goals Against: " + goalsagainst + ")";
    }
    public static void main(String[] args) {
        WorldCup Morocco1 = new Morocco("Morocco", "En-Nesyri", 6, 0);
        System.out.println(Morocco1.toString());
    }
}
public class Croatia extends WorldCup {
    private int goalsscored;
    private int goalsagainst;
    public Croatia (String country, String bestplayer, int goalsscored, int goalsagainst){
        super(country, bestplayer);
        this.goalsscored = goalsscored;
        this.goalsagainst = goalsagainst;
    }
    public int getCroatiaScored() {
        return goalsscored;
    }
    public int getgoalsagainst() {
        return goalsagainst;
    }

    @Override
    public String toString() {
         return "WorldCup (country: " + country + ", bestplayer: " + bestplayer + ", Goals Scored: " + goalsscored + ", Goals Against: " + goalsagainst + ")";
    }
    public static void main(String[] args) {
        WorldCup Croatia1 = new Croatia("Croatia", "Modric", 8, 2);
        System.out.println(Croatia1.toString());
    }
}
public class France extends WorldCup {
    private int goalsscored;
    private int goalsagainst;
    public France (String country, String bestplayer, int goalsscored, int goalsagainst){
        super(country, bestplayer);
        this.goalsscored = goalsscored;
        this.goalsagainst = goalsagainst;
    }
    public int getFranceScored() {
        return goalsscored;
    }
    public int getgoalsagainst() {
        return goalsagainst;
    }

    @Override
    public String toString() {
         return "WorldCup (country: " + country + ", bestplayer: " + bestplayer + ", Goals Scored: " + goalsscored + ", Goals Against: " + goalsagainst + ")";
    }
    public static void main(String[] args) {
        WorldCup France1 = new France("France", "Mbappe", 13, 6);
        System.out.println(France1.toString());
    }
}
public class Argentina extends WorldCup {
    private int goalsscored;
    private int goalsagainst;
    public Argentina (String country, String bestplayer, int goalsscored, int goalsagainst){
        super(country, bestplayer);
        this.goalsscored = goalsscored;
        this.goalsagainst = goalsagainst;
    }
    public int getArgentinaScored() {
        return goalsscored;
    }
    public int getgoalsagainst() {
        return goalsagainst;
    }

    @Override
    public String toString() {
         return "WorldCup (country: " + country + ", bestplayer: " + bestplayer + ", Goals Scored: " + goalsscored + ", Goals Against: " + goalsagainst + ")";
    }
    public static void main(String[] args) {
        WorldCup Argentina1 = new Argentina("Argentina", "Messi", 10, 5);
        System.out.println(Argentina1.toString());
    }
}
WorldCup.main(null);
Morocco.main(null);
France.main(null);
Croatia.main(null);
Argentina.main(null);

WorldCup (country: Qatar, bestplayer: who knows)
WorldCup (country: Morocco, bestplayer: En-Nesyri, Goals Scored: 6, Goals Against: 0)
WorldCup (country: France, bestplayer: Mbappe, Goals Scored: 13, Goals Against: 6)
WorldCup (country: Croatia, bestplayer: Modric, Goals Scored: 8, Goals Against: 2)
WorldCup (country: Argentina, bestplayer: Messi, Goals Scored: 10, Goals Against: 5)

Part 2

Add a getAge method in the Person super class
Create a new subclass Student with additional members of your choice to personalize the Student class
Create a new subclass Teacher with additiona members of your choice
Override the toString method using the @Override to print a Student and teacher object with new members
Print the student and teacher.

public class Person {
    protected String name;
    protected String birthday;
    protected int age;
 
    public Person (String name, String birthday, int age){
       this.name = name;
       this.birthday = birthday;
       this.age = age;
    }
 
    public String getName(){
       return name;
    }

    public String getBirthday(){
      return birthday;
    }

    public int getAge() {
      return age;
    }
 }
 
 public class Student extends Person {
    private int grade;
    private double gpa;
 
    public Student (String name, String birthday, int age, int grade, double gpa) {
       super(name, birthday, age);
       this.grade = grade;
       this.gpa = gpa;
    }
 
    public int getGrade(){
       return grade;
    }
    public double getGPA(){
      return gpa;
    }

    @Override
    public String toString(){
      return "Person (name: " + name + ", grade: " + grade + ", birthday: " + birthday + ", Age: " + age + ", GPA: " + gpa + ")";
    }
 }

 public class Teacher extends Person {
   private String classtaught;
   private int yearsteaching;

   public Teacher (String name, String birthday, int age, String classtaught, int yearsteaching) {
      super(name, birthday, age);
      this.classtaught = classtaught;
      this.yearsteaching = yearsteaching;
   }

   public String getClassTaught(){
      return classtaught;
   }

   public int getYearsTeaching(){
      return yearsteaching;
   }


   @Override
    public String toString(){
      return "Person (name: " + name + ", Class Taught: " + classtaught + ", birthday: " + birthday + ", Age: " + age + ", Years Teaching: " + yearsteaching + ")";
    }
}

Person John = new Teacher("John Mortensen", "idk", 65, "Computer Science", 5);
System.out.println(John.toString());
Person Rohan = new Student("Rohan Gaiks", "March 2", 16, 11, 4.0);
System.out.println(Rohan.toString());
System.out.println(Rohan.getAge());

Person (name: John Mortensen, Class Taught: Computer Science, birthday: idk, Age: 65, Years Teaching: 5)
Person (name: Rohan Gaiks, grade: 11, birthday: March 2, Age: 16, GPA: 4.0)
16