Notes

Inheritance is the ability to inherit characteristics from super class to sub classes
- Reduces risk of error and reduces redundancy
- extends key word used to inherit characteristics from a class
- Constructors in a sub class needs to have at least the same definition as the old class
- super() to call supper class's constructor which must have all relevant parameters passed into it
- @Override to overriding methods of a super class and makes it readable
Tree called inheritance hierarchies where lower subclasses inherit upper super classes in the hierarchy
Polymorphism allows methods to have multiple forms for code reusability with different forms/implementations

Homework

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{
    private int wins;
    private int losses;
    private int draws;

    public WorldCup(int wins, int losses, int draws){
        this.wins = wins;
        this.losses = losses;
        this.draws = draws;
    }

    public String toString(){
        return ( "{ \"wins\": "  +this.wins+  ", " + "\"losses\": "  +this.losses+  ", " + "\"draws\": "  +this.draws+ " }" );
    }

    public static void main(String[] args) {
        Argentina argentina = new Argentina(5, 1, 0);
        System.out.println("Argentina: " + argentina);

        Croatia croatia = new Croatia(3, 1, 2);
        System.out.println("Croatia: " + croatia);

        France france = new France(4, 1, 0);
        System.out.println("France: " + france);

        Morocco morocco = new Morocco(4, 0, 1);
        System.out.println("Morocco: " + morocco);

        Brazil brazil = new Brazil(3, 2, 0);
        System.out.println("Brazil: " + brazil);
    }
}

public class Argentina extends WorldCup{
    public Argentina(int wins, int losses, int draws){
        super(wins, losses, draws);
    }
}

public class Croatia extends WorldCup{
    public Croatia(int wins, int losses, int draws){
        super(wins, losses, draws);
    }
}

public class France extends WorldCup{
    public France(int wins, int losses, int draws){
        super(wins, losses, draws);
    }
}

public class Morocco extends WorldCup{
    public Morocco(int wins, int losses, int draws){
        super(wins, losses, draws);
    }
}

public class Brazil extends WorldCup{
    public Brazil(int wins, int losses, int draws){
        super(wins, losses, draws);
    }
}
WorldCup.main(null);

Argentina: { "wins": 5, "losses": 1, "draws": 0 }
Croatia: { "wins": 3, "losses": 1, "draws": 2 }
France: { "wins": 4, "losses": 1, "draws": 0 }
Morocco: { "wins": 4, "losses": 0, "draws": 1 }
Brazil: { "wins": 3, "losses": 2, "draws": 0 }

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 additional 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.

import java.util.Date;
import java.text.SimpleDateFormat;
import java.time.LocalDate;
import java.time.Period;
import java.time.ZoneId;

public class Person {
   public String name;
   public LocalDate birthday;

   public Person (String name, LocalDate birthday){
      this.name = name;
      this.birthday = birthday;
   }

   public String getName(){
      return name;
   }

   public int getAge(){
      return Period.between(this.birthday, LocalDate.now()).getYears();
   }

   public String toString() {
      return ( "{ \"name\": "  +this.name+  ", " + "\"birthday\": "  +this.birthday+ " }" );
   }
 }
 
public class Student extends Person {
   public int grade;
   public double gpa;

   public Student (String name, LocalDate birthday, int grade, double gpa) {
      super(name, birthday);
      this.grade = grade;
      this.gpa = gpa;
   }

   public int getGrade(){
      return grade;
   }

   public double getGPA(){
      return gpa;
   }

   @Override
   public String toString(){
      return ( "{ \"name\": "  +this.name+  ", " + "\"birthday\": "  +this.birthday+  ", " + "\"grade\": "  +this.grade+  ", " + "\"gpa\": "  +this.gpa+ " }" );
   }
}

public class Teacher extends Person {
   private String subject;

   public Teacher (String name, LocalDate birthday, String subject){
      super(name, birthday);
      this.subject = subject;
   }

   @Override
   public String toString(){
      return ( "{ \"name\": "  +this.name+  ", " + "\"birthday\": "  +this.birthday+  ", " + "\"subject\": "  +this.subject+ " }" );
   }
}

public class Main{
   public static void main(String[] args){
      LocalDate dob = LocalDate.parse("2000-01-01");
      Person person = new Person("Person", dob);
      System.out.println(person.toString());

      Student student = new Student("Student", dob, 11, 4.0);
      System.out.println(student.toString());
      
      Teacher teacher = new Teacher("Teacher", dob, "Computer Science");
      System.out.println(teacher.toString());
   }
}

Main.main(null);

{ "name": Person, "birthday": 2000-01-01 }
{ "name": Student, "birthday": 2000-01-01, "grade": 11, "gpa": 4.0 }
{ "name": Teacher, "birthday": 2000-01-01, "subject": Computer Science }