Greenfoot Introduction (2)


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Greenfoot Introduction (2)

  1. 1. Introduction To Greenfoot Part-2
  2. 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  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] ( Introduction to Greenfoot 2 Eueung Mulyana |
  3. 3. 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, Introduction to Greenfoot 3 Eueung Mulyana |
  4. 4. Outline  Class Display Revisited  Class Editor  The Leaf Class  The Wombat Class  The WombatWorld Class Introduction to Greenfoot 4 Eueung Mulyana |
  5. 5. 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) Introduction to Greenfoot 5 Eueung Mulyana |
  6. 6. 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“ Introduction to Greenfoot 6 Eueung Mulyana |
  7. 7. Class Editor (2) Introduction to Greenfoot 7 Eueung Mulyana |
  8. 8. 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 Introduction to Greenfoot 8 Eueung Mulyana |
  9. 9. The Wombat Class (1) import necessary packages class header; Wombat is a subclass from Actor data (constants and variables) class constructor and methods Introduction to Greenfoot 9 Eueung Mulyana |
  10. 10. 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() Introduction to Greenfoot 10 Eueung Mulyana |
  11. 11. 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 Introduction to Greenfoot 11 Eueung Mulyana |
  12. 12. The Wombat Class (4) Introduction to Greenfoot 12 Eueung Mulyana |
  13. 13. The Wombat Class (5) this method is inherited from the superclass Actor Introduction to Greenfoot 13 Eueung Mulyana |
  14. 14. The Wombat Class (6) change direction 90 degrees to the left Introduction to Greenfoot 14 Eueung Mulyana |
  15. 15. 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 Introduction to Greenfoot 15 Eueung Mulyana |
  16. 16. The Wombat Class (8) Introduction to Greenfoot 16 Eueung Mulyana |
  17. 17. The Wombat Class (9) if object reaches one of the borders, do nothing! the object moves setLocation() is forward; inherited from Actor depends on its direction Introduction to Greenfoot 17 Eueung Mulyana |
  18. 18. 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! Introduction to Greenfoot 18 Eueung Mulyana |
  19. 19. The WombatWorld Class (1)  1 constructor : WombatWorld()  2 methods : – populate() – randomLeaves() Introduction to Greenfoot 19 Eueung Mulyana |
  20. 20. The WombatWorld Class (2) calls the World constructor sets the background. the method is inherited from the superclass World cell.jpg Introduction to Greenfoot 20 Eueung Mulyana |
  21. 21. The WombatWorld Class (3) Introduction to Greenfoot 21 Eueung Mulyana |
  22. 22. The WombatWorld Class (4) Create a Leaf object at a random position (x,y); repeat howmany times Introduction to Greenfoot 22 Eueung Mulyana |
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