Greenfoot Introduction (1)

kakihijau.googlepages.com

Introduction To

GreenfootPart-1

2Introduction to Greenfoot

Eueung Mulyana | kakihijau.googlepages.com

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).



Introduction

„Greenfoot is a software tool designed to let beginners get experience with object-oriented programming. It supports development of graphical applications in the Java™ Programming Language“

Designed and implemented at the University of Kent and Deakin University

Copyright held by Poul Henriksen and Michael Koelling

More information at http://www.greenfoot.org

Part of the content of these slides is based on the Greenfoot Tutorial made by Michael Koelling, publicly accesible at the website



Outline

Visual Interface Creating Objects Interaction with Objects Removing Objects Objects‘ Action Simulation „Run“ Scenario plane Scenario turtleGraphics Scenario ants Scenario lunarlander



Visual Interface (scenario wombats)



Visual Interface

Consists of 3 main parts

The world– The large canvas that covers the majority of the window– Has a title e.g. WombatWorld– The enviroment („the world“) where objects exist

Class display– Contains all Java classes involved in the scenario– 3 groups: World, Actor and other classes

Execution controls– Controls the action of each object: the „Act“ button– Controls simulation: „Run“, „Pause“, slider– Resets the scenario



Creating Objects (1)

(Left-)Click on the Wombat or Leaf class to make it active

To create and place an object into the world :– Activate a class then shift+click somewhere in the World– Right-click a class (e.g. Wombat class) to open the class

context menu, select the „New Wombat()“ item then click somewhere in the World



Creating Objects (2)

Classcontext menu

Creating 3 objects and placing them into the World



Interaction with Objects (1) Methods of an

object can directly be invoked

„A method is a single action that an object can perform“

Right-click on one object to show its (object) context menu, where you can select a method to ask the object to do „something“

turnleft() move()



Interaction with Objects (2)

The world where the wombats live (WombatWorld) is actually an object, too

But there may exist only one World object at a time

It functions as a container for Actor objects (e.g. Wombat, Leaf etc.)

Single method invocation is still possible for the World object; just right-click the title „WombatWorld“ and select a method from the menu




populate() randomLeaves()




A method may have one or more parameters You will be requested to give value(s) of the

parameter(s) when you invoke such a method Try the method setDirection() from a Wombat

object or the method randomLeaves() from the WombatWorld

A method may also return one value (or reference to an object) if it is invoked

Try foundLeaf() or getLeavesEaten() from a Wombat object



Removing Objects (1)

An object can be removed by selecting item „Remove“ from the object context menu

Clicking the „Reset“ button or creating a new World object from the class context menu may remove all objects; however it actually depends on the constructor implementation of the World class (*)



Removing Objects (2)



Objects‘ Action

Each Actor object has a special method called act() Pressing the button „Act“ on the control panel

means asking Greenfoot to execute act() method for all objects in the world

An object acts by doing „whatever it wants to do“ e.g.:– Wombats move forward, if they find a leaf in their path,

they will eat it– Leaves do nothing

The action depends actually on how act() method is defined; that is, we can program object behaviors!!



Simulation „Run“

A scenario can be run by clicking the „Run“ button

This equivalent to clicking the „Act“ button over and over again very quickly

The slider next to the „Act“ and „Run“ buttons sets the „running/simulation“ speed

Make an experiment with scenario wombats– Click „Reset“ if you have already some objects– Select Populate() from the WombatWorld menu– Click „Run“



Simulation „Run“

Running wombats scenario



Scenario plane (1)

Choose „Open ...“ from the „Scenario“ menu and select the plane scenario from the Greenfoot sample scenarios

Press the „Compile all“ button, if necessary

Instantiate a Plane object and place somewhere in the world

Run the scenario by pressing „Run“

Try to drag the ControlKnob object and observe the result



Scenario plane (2)



Scenario plane (3)



Scenario turtleGraphics (1)

Choose „Open ...“ from the „Scenario“ menu and select the turtleGraphics scenario from the Greenfoot sample scenarios

Press the „Compile all“ button, if necessary Instantiate several turtle objects (CircleTurtle,

SquareTurtle, FlowerTurtle and SpiralTurtle) and place somewhere in the world

Run the scenario by pressing „Run“ Observe the result



Scenario turtleGraphics (2)



Scenario ants (1)

Choose „Open ...“ from the „Scenario“ menu and select the ants scenario from the Greenfoot sample scenarios

Press the „Compile all“ button, if necessary By default (standard Greenfoot 1.3 distribution)

you will have several objects, which are actually formed together as the World object is created; these objects are instances of the class AntHill and Food; other objects will be created „on-the-fly“

Run the scenario by pressing „Run“ Observe the result



Scenario ants (2)



Scenario lunarlander (1)

Choose „Open ...“ from the „Scenario“ menu and select the lunarlander scenario from the Greenfoot sample scenarios

Press the „Compile all“ button, if necessary By default you will have a Lander object, which

is actually formed together as the World object is created

Now you are ready to play the game; run the scenario by pressing „Run“

The rocket thrust can be controlled by pressing the „down“ key on the keyboard



Scenario lunarlander (2)

Greenfoot Introduction (1)

Education

Transcript of Greenfoot Introduction (1)