Oracle Java Tutorials
Videos
Handling Exceptions (16:23)
Multiple Exceptions (12:11)
Handle exceptions using try/catch/finally clauses, try-with-resource, and multi-catch statements
Create and use custom exceptions
2 Class Design and Exceptions
2-4: Exceptions and Assertions
Section 2 Quiz
2-4 Practice: Exceptions and Assertions
Mindfulness
Previous week review
write down access code and complete after lesson
Repl.it assignment / Canvas assignment
Resource reinforcement and clarification
Interface vs Abstract classes
Polymorphism
Sample code http://ideone.com/9PiHjl
Components / implications:
Base methods can be overriden in derived classes.
Overriden method code will be executed even from a call that seems to be from base type. This is dynamic dispatch.
A derived type is usable in a context that expects the base type, such as in a collection or as a parameter. This is called subtyping. (More next week.)
2-3
Vocabulary
Bike toString
Project
public class Animal
{
public void showSpecies()
{
System.out.println("Regular animal");
}
public void makeSound()
{
System.out.println("Grrrrr");
}
}
public class Dog extends Animal
{
public void showSpecies()
{
System.out.println("Dog");
}
public void makeSound()
{
System.out.println("Woof");
}
}
public class Cat extends Animal
{
public void showSpecies()
{
System.out.println("Cat");
}
public void makeSound()
{
System.out.println("Meow");
}
}
public class Program
{
public static void main(String[] args)
{
Cat felix = new Cat();
Dog fido = new Dog();
Animal[] myPets = { felix, fido };
for (Animal anAnimal : myPets)
{
anAnimal.showSpecies();
anAnimal.makeSound();
}
}
}