3.2 Java3002: creating and manipulating turtles and pictures in a

Revised: Sat Apr 02 13:20:42 CDT 2016

This page is included in the following Books:

• ITSE 2321 - Object-Oriented Programming (Java)
• Object-Oriented Programming (OOP) with Java

Table of contents

• Preface
  • Viewing tip
    • Figures
    • Listings
• Preview
• Discussion and sample code
• Run the program
• Summary
• What's next?
• Online video links
• Miscellaneous
• Complete program listing

Preface

This module is one of a series of modules designed to teach you about Object-Oriented Programming (OOP) using Java.

Before embarking on the material in this module, you should have studied and should understand all of the material in the modules identified as Java1600 through Java1630 in the section of this book titled Essence of OOP and you should have studied and should understand allof the material in the following books:

• Programming Fundamentals with Java
• Java OOP Self-Assessment

The program described in this module requires the use of the Guzdial-Ericson multimedia class library. You will find download, installation, and usageinstructions for the library at Java OOP: The Guzdial-Ericson Multimedia Class Library .

Viewing tip

I recommend that you open another copy of this document in a separate browser window and use the following links to easily find and view the Figures and Listings while you are reading about them.

Figures

• Figure 1 . Graphic screen output.
• Figure 2 . Command-line output.
• Figure 3 . Commands to compile and execute the application.
• Figure 4 . Constructors for the World class.
• Figure 5 . Constructors for the Turtle class.
• Figure 6 . Constructors for the Picture class.

Listings

• Listing 1 . The driver class.
• Listing 2 . Beginning of the class named Prob01Runner.
• Listing 3 . The constructor for the Prob01Runner class.
• Listing 4 . Three accessor methods.
• Listing 5 . The beginning of the run method.
• Listing 6 . Add text to the image.
• Listing 7 . Manipulate the turtle named joe.
• Listing 8 . Manipulate the turtle named sue.
• Listing 9 . Source code for Prob01.

Preview

In this module, I will explain a program that uses Java and Ericson's media library to (see Figure 1 ) :

• Add a picture and two turtles to a world.
• Manipulate the turtles, their colors, and their pens.

Stated in more detail, the program will:

• Create a Picture object from an image file and replace the default white Picture in a World object with the new Picture object.
• Place two Turtle objects in a World object.
• Apply a series of operations to manipulate the two turtle objects so as to produce a specific graphic output.
• Provide accessor methods to get references to two Turtle objects and the World object.
• Use the references to get information from the World and Turtle objects and display that information on the command-line screen.
• Display text on a Picture in a World object.

Program output

Figure 1 shows the graphic screen output produced by this program.

Figure 1 - Graphic screen output.

Figure 2 shows the text output produced by the program on the command line screen.