Introduction To Greenfoot Part-2

Disclaimer This document is intended to give a beginner an introductory material for the Greenfoot system. Greenfoot is a software framework made by Poul Henriksen and Michael Koelling at University of Kent / Deakin University. More information can be found at http://www.greenfoot.org This document is available „AS IS“ free of charge for personal use and non-commercial redistribution. It may not be sold for profit or included in other packages which are sold for profit without written authorisation. This document is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; your use of the document is at your sole risk. Reusing and modifying (part of) this document is allowed, as long as you state explicitly that your work is based on the original document produced by the copyright holder: Eueung Mulyana. The author can be contacted via eueung-[at]-yahoo.com (http://kakihijau.googlepages.com).

Purpose This is the second part of the document „Introduction to Greenfoot“ and focuses on understanding the wombats scenario Part of the content of these slides is based on the Greenfoot Tutorial made by Michael Koelling, publicly accesible at the Greenfoot website, http://www.greenfoot.org

Outline Class Display Revisited Class Editor The Leaf Class The Wombat Class The WombatWorld Class

Class Display Revisited Class display contains all classes which are used in a scenario Class World and Actor are abstract superclasses, part of the Greenfoot system Scenario wombats has 2 actor classes (Wombat, Leaf)

Class Editor (1) We can modify objects behaviour by editing the source code of the corresponding class To display the source code editor: Double-click the class Right-click the class, choose the item „Open editor“

Class Editor (2)

The Leaf Class The simplest class compared to the Wombat and WombatWorld class Leaf objects do nothing! As you can see in the previous slide, the Leaf class has no statement and consists of an empty constructor

The Wombat Class (1) import necessary packages class header; Wombat is a subclass from Actor data (constants and variables) class constructor and methods

The Wombat Class (2) 4 constants : EAST, WEST, NORTH, SOUTH 2 variables : direction, leavesEaten 1 constructor : Wombat() 8 methods : getLeavesEaten(), foundLeaf(), eatLeaf() setDirection(), turnLeft() canMove(), move() act()

The Wombat Class (3) constructor  initialising direction and leavesEaten is there any Leaf object in my position? this method is inherited from the superclass Actor remove that Leaf object update the variable leavesEaten

The Wombat Class (4)

The Wombat Class (5) this method is inherited from the superclass Actor

The Wombat Class (6) change direction 90 degrees to the left

The Wombat Class (7) these methods are inherited from Actor new coordinate if the object moves forward; depends on its direction checks if the object reaches the edges of the world

The Wombat Class (8)

The Wombat Class (9) if object reaches one of the borders, do nothing! the object moves forward; depends on its direction setLocation() is inherited from Actor

The Wombat Class (10) if you find leaves, eat ! if you don‘t find leaves, but you can move forward, then move! if you don‘t find leaves and you also cannot move, then turn to the left!

The WombatWorld Class (1) 1 constructor : WombatWorld() 2 methods : populate() randomLeaves()

The WombatWorld Class (2) calls the World constructor sets the background. the method is inherited from the superclass World cell.jpg

The WombatWorld Class (3)

The WombatWorld Class (4) Create a Leaf object at a random position (x,y); repeat howmany times