• Homework Solution
• Inheritance
• Super
• Packages
• Import
• Polymorphism
• Overloading Methods

• "is-a" relationship
• A sub-class (child) inherits properties and behaviors from a super-class (parent)

• Properties & Methods that are common to child Classes should go in the parent Class

 public class Starship {
    private int warpSpeed;
    private int distanceTraveled;
    private int numberOfCrewMembers;
    public boolean travelTo(int xCoord, int yCoord, int zCoord);
 }

 public class Enterprise extends Starship {
    private int episodesAppearedIn;
    public void fireTorpedos(Starship target);
    public void teleport(String crewMember);
 }

 Enterprise enterprise = new Enterprise();
 enterprise.travelTo(0, 13, 26);

• Every Class inherits from another Class
• Every Class has Object as a super-class
• Object provides methods like toString() & equals()
• Object is inherited by default, even if not explicit

• The "super" keyword references a Class's parent Class.
• Used to call a parent Class's constructor, access a parent Class's properties, or call a parent Class's methods.
• Calling the super constructor must be the first line of a Constructor.

 public class Enterprise extends Starship {

      //Enterprise constructor
      public Enterprise(int crewlimit) {
           super(crewlimit);
      }

      public String printDetails() {
           super.printStarship();
      }
 }

• Used to organize and uniquely name Classes

• The directory structure where a .java file exists, decides it's Package.
• Eclipse will automatically move files for you once you've added the package declaration to the top of a Java file.

 package com.foundations.furniture;

 public class Chair {}

• To use Classes from a different Package, import them at the top of your .java file.
• You can import an individual Class or a Package as a whole.

 import Java.lang.Math;
 import Java.io;

 public abstract class Animal {
     public abstract String speak();
 }

 public class Dog extends Animal {
     public String speak() { return "ruff"; }
 }

 public class Cat extends Animal {
     public String speak() { return "meow"; }
 }

 Animal dog = new Dog();
 Animal cat = new Cat();

 dog.speak();
 cat.speak();

• Method overloading occurs when a method is declared with the same identifier as an existing method, but has a different set of arguments.
• Methods cannot have the same identifier and the same arguments.
• Different return types alone will not overload a method.

 public static void aMethod(int x) {}
 public static void aMethod(String word) {}
 public static void aMethod(int num1, int num2) {}