COSC 135 B Lab 1

Objectives

• Locate class web-pages and dropfolders.
• Experience the basics of using CodeWarrior.
• Basic Java String operations and errors.
• Learn some simple BreezyGUI commands.

1. Login to a Windows NT machine and navigate (via MyComputer or Windows Explorer) to your folder on the H:\ drive. Create a folder called cosc135 (or programming1 etc.) and in that new folder, create a subfolder called lab01.
2. Open another navigation window and proceed to the folder G:\MathCS (the dropfolders drive). Arrange your desktop so that both the BreezyGUI subfolder on the G-drive and your newly created cosc135 folder on the H-drive are visible.
3. Drag the BreezyGUI folder onto your cosc135 folder. You should now have a copy of the classes in the BreezyGUI package.
   
   We will be using CodeWarrior from Metrowerks for our programming environment. Click here for a brief explanation of how to start CodeWarrior and setup a new project. Go ahead and setup a project called HelloWorld in your lab01 folder on the H-drive. The class name should be HelloWorld. Since we'll be using BreezyGUI to construct our windowing interfaces for our programs, our java source files will look something like this:
   
   /* ProgramName.java

 
   Author:
   Date Started:
   Description:
*/

import java.awt.*;
import BreezyGUI.*;

public class ProgramName extends GBFrame {
   // GUI design and declaration goes here

   // data and variable declarations

   public void buttonClicked (Button pressedButton){

      // handle the click of all buttons here
   } // end of buttonClicked method

   public static void main ( String[] args){
      // create a new object, set its size and turn it on
      Frame frm = new ProgramName();
      frm.setSize (widthInPixels, heightInPixels);
      frm.setVisible (true);
   } // end of main method
} // end of class ProgramName

You'll have to add details to the topmost comments, change the three occurences of ProgramName to match the name of the file (remember, the class name must match exactly the filename without the .java extension), and select a width and height for the setSize method. In a Java source file, any text between /* and */ is considered a comment (even if it extends over several lines). As well, any text after // on a single line is also a comment. Look at the code above for examples of both types of comments.

4. In CodeWarrior, copy the code above into the HelloWorld.java file. You can double click on the HelloWorld.java file in the project window to open an editor window. Be sure you change ProgramName to HelloWorld.
5. In the GUI design section, add the line
             Button messageButton = addButton ("Click to Print",1,1,1,1);
   This line adds a button named "messageButton" in the first row, first column of our GUI grid. The button is 1 column wide and 1 row tall. In general, BreezyGUI items take the parameters (initial value, row, column, width, height).
6. To make our button do something when we click it, add the line
             messageBox ("Hello there great big world!");
   to the buttonClicked method, between the curly brackets { and }. The messageBox command will open a box that contains the String you pass in. Anything in double quotes is considered a String in Java.
7. Select Run from the Project menu in CodeWarrior (near the bottom), and observe any errors you receive. Try to fix your errors. If you need help, ask. When you get your application to run, be sure to close the messageBox by clicking on the OK button, and then the DOS window by pressing [ENTER]. Be sure to save your project, once you get it to run.
8. Sometimes we will have several strings that we need to print together. Java allows us to concatenate strings using the + operation. Briefly, "string1" + "string2" is "string1string2". You can also treat literal numbers, like 4 or 9, as strings, thus (in Java), "I am " + 39 + " years old." gives "I am 39 years old." (notice the spaces), whereas "I am" + 39 + "years old." gives "I am39years old.". In the data-variable section of your HelloWorld.java file, add a string data field called myName. For me, the line would be
         String myName = "Tom";
   Modify your code so that the messageBox displays the message Hello world. My name is ????? (where ???? is your name, and you use + myname inside the messageBox method call. Once your code runs, print out the messageBox command you used here:
   
   
   
   
   
   
   
9. Add another variable called age to the class file. The line should be something like (if you are 39 years old):
        int age = 39;
   Modify the messageBox command so that the printout reads "My name is ??? and I am ??? years old" (again, the ??? are filled in by the variables name and age). Record your messageBox command below (once you get the code to run).
   
   
   
   
   
   
10. Edit your last messageBox command by adding \n (backslash n with no spaces) just before the and I am part of your messageBox command. Describe what the \n did to the printed material.
    
    
    
    
    
    
11. Hopefully your messageBox command contains something like + age + in its input. Change age to age*2 and explain what happened to the output.
    
    
    
    
    
12. Now replace the age*2 with age / 0. Describe what happened.
    
    
    
    
    
    
13. Fix your HelloWorld.java file by replacing the age / 0 with just age again. Run the code to make sure it compiles and runs correctly. Now delete the semicolon at the end of the messageBox command. Try to run the program and explain what happens.
    
    
    
    
    
    
    
14. Put the semicolon back (be sure your code runs) and delete the word public from the main method declaration line. Try to run the code and explain what happens.
    
    
    
    
    
    
    
    
    
    
15. Put the word public back in your code and make sure it compiles and runs. Once it does, save your project one last time. In your cosc135 folder, create a subfolder whose name is your name (my subfolder would be called TomLinton). Copy your lab01 folder (with your HelloWorld.* files) into the folder with your name. You should be able to right-click and drag the folder, then select Copy (not Move). Open another navigation window and navigate to G:\Lintont\cosc135. That folder should have a Handin subfolder. Drag the folder with your name on it onto the Handin folder icon. In the future, you can hand stuff in by placing it in your folder, inside my cosc135\Handin folder. If you finish, turn in this paper before you leave. 
    
    
    
16. Look at the FahrenheitToCentigrade.java file. You will soon be asked to code a PiggyBank.java file. This program will get an integer number of pennies, nickels, dimes and quarters from the user and report the number of dollars and leftover change equivalent to these coins. For example, 6 pennies, 8 nickels, 12 dimes, and 6 quarters would be 3 dollars and 16 cents. Your GUI will require four integer input fields and a compute button. Draw a picture of your GUI and try to create the code (based on the default.java template above) that constructs your GUI. For now, you can leave the buttonClicked method empty (just as it is in default.java). All you're aiming for is the GUI design.