Using Jeroo To Teach Object-Oriented Concepts By Christian Digout

What is Jeroo? A tool for helping students learn object- oriented concepts including: ◦ Instantiating and using objects ◦ Constructors ◦ Writing methods to extend behavior ◦ Information Hiding

Jeroo Layout

Example of a Program

Features of the Jeroo Application Animation showing Jeroos moving around the island Source code highlighting synchronized with execution Stepwise or continuous execution mode Choice of execution speeds Ability to switch between execution modes and change speeds at will Error messages

Summary of Jeroo Small Object-Oriented Language Only one class, the Jeroo class Can instantiate up to four Jeroos Three attributes per Jeroo ◦ location ◦ direction ◦ number of flowers

Summary of Jeroo Six constructors to initialize the attributes Seven action methods Seven sensor methods to examine the immediate surroundings Four relative directions

Instantiation The process of creating an instance of an object. Jeroo has 6 constructors ◦ Including a default constructor The new operator is used to instantiate objects

Constructors

Objects and Jeroo States (or member variables) Position (x, y) Direction (North, East, South, West) Number of flowers Information Hiding ◦ A Jeroo’s data is protected ◦ Protects data integrity ◦ Need to use member methods to access member variables

Behavior and Member Methods

Behaviors and Member Members

Student Assignments From the Jeroo website: ◦ Pick All Flowers ◦ The Maze ◦ Walk the Lake ◦

Jeroo Use of constructors Get use to the dot-notation Use member methods Can extend the Jeroo class with new methods

Java – Building a Class public class Circle { private static final double PI = 3.14; private double radius; public Circle() { radius = 1; } public void setRadius(double newRadius) { radius = newRadius; } }

Jeroo Class It is written in Java Ask students what would it include? ◦ 6 constructors ◦ Member variables ◦ Member methods

Turtle Graphics Downloaded from: wadsworth/course_products_wp.pl?fid=M 20bI&product_isbn_issn= wadsworth/course_products_wp.pl?fid=M 20bI&product_isbn_issn= Part of textbook resources for: ◦ Fundamentals of Java by Lambert/Osbourne Allows students to create simple graphics using Java

Turtle Graphics Good for showing: ◦ Composition “has a” relationships ◦ Inheritance “is a” relationships ◦ Interfaces ◦ Abstract classes

Turtle Graphics Create a Shape Interface AbstractShape can implement Shape ◦ Can implement members that would be the same for all shapes such as:  X and Y coordinates  Move function ◦ Abstract methods would be:  Area  Draw

Shape Hierarchy Can implement Circle and Rectangle Classes with students. ◦ Extend Abstract Shape Assignment: ◦ Students implement a Triangle Class ◦ Students can add a Perimeter Method to the hierarchy