Challenge

Quick Index

Problem Statement
Point
Circle
Running The Grahics System
Ellipse

This challenge follows the examples.

Our challege is to code Point, Circle and Ellipse so that we can run our graphics system.

First download this code into your working directory.

Then follow the instructions below for coding the three classes.

Point

Point is the core object in graphics. And we've already coded most of it!

Point.java is provided for you.
There are two methods with the tag "//CODE HERE".
Finish those two methods

Circle

Circle is a composite -- i.e. it is made up of component(s). In it's case, it has a "Point" child.

Circle.java is started for you.

Add These Private Ivars:

Find tag "//CODE HERE (ivars)"
An ivar "center" of type "Point"
An ivar "radius" of type "int"

Code:

Find all methods with tag "//CODE HERE".
Finish those methods

Running The Grahics System

Once Circle is finished and compiling okay you can fire up the graphics system.

One way is in the console, in your working directory:

">javac GraphicsApp.java
>java GraphicsApp"

If you hit "Go" that will kick off the graphics. And hitting "Randomize" will change things up.

Ellipse

Ellipse is a composite -- i.e. it is made up of component(s). In it's case, it has a "Point" child.

Ellipse.java is started for you.

Add These Private Ivars:

Find tag "//CODE HERE (ivars)"
An ivar "center" of type "Point"
An ivar "a" of type "int"
An ivar "b" of type "int"

Code:

Find all methods with tag "//CODE HERE".
Finish those methods

To activate Ellipse (rather than Circle) you can tweak the constructor in "OuterSpace" (uncomment the Ellipse line). Then fire up the graphics system again.

Introduction To Objects With Java (Chapter 501 - Composition)

Chapter 501 - Composition Challenge

Contents Concepts Example1 Example2 References Challenge

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