Objectives:

• Become more familiar with Java WorkShop (Exercise I).
• Learn the mechanics of creating a class file (Exercise II).
• Enhance a class (Exercise III).

The second and third parts will be based on a variation of the Button class that was developed during the lecture. You should think about how you are going to do Exercise III before coming into the lab. Note: You can save time by viewing the laboratory instructions in the browser and cutting and pasting code in. However, you should look carefully at the code and make sure that you understand it before coming to the lab. You can ask in the lab or the lecture if you don't understand it.

Check-off procedure:

Be sure to bring your copy of A Beginner's Guide to Java WorkShop 3.0: http://vip.cs.utsa.edu/classes/JavaInfo/JavaWorkShop.html You must attend the recitation and sign in. You are considered to be checked off if you completed the first two parts and have made some progress on the third part. The TA will look at your console to see that you have executed the programs. Classmates please help each other.

Laboratory details:

• Exercise I: The Warm Up
  • Bring up Java WorkShop.

  • Make sure that only the default portfolios show in the Navigation Window.

  • Work through the example in the Beginner's Guide to Java Workshop Using standard packages. This example uses the Date class which will be used in the next parts.

  If you were successfully checked off on this last time you can skip it.

• Exercise II: Making a Button
  • Create a new portfolio called ButtonCode.

  • Create a new standalone project in the ButtonCode portfolio called ButtonMain. Enter the following code:

    public class ButtonMain {
    
        /**
         * Constructor.
         */  
        public ButtonMain () {
        }
    
        public static void main(String args[]) {
            Button mybutton = new Button();
            mybutton.PushButton();
            System.out.println("mybutton has pushed state = " + mybutton.GetState());
            mybutton.ClearButton();
            System.out.println("mybutton has pushed state =  " + mybutton.GetState());
            System.out.println("mybutton was created on " + mybutton.GetWhenMade());
        }
    }
    
    

  • Create a new file that contains the following code:

    import java.util.*;
    
    public class Button {
        private boolean myIamPushed;
        private Date myCreationDate;
    
        public Button () {
            myIamPushed = false;
            myCreationDate = new Date();
        }
    
        public void ClearButton() {
            myIamPushed = false;
        }
    
        public void PushButton() {
            myIamPushed = true;
        }
    
        public boolean GetState(){
            return myIamPushed;
        }
    
        public String GetWhenMade() {
            return myCreationDate.toString();
        }
    }
    
    

    Save the file as Button.java in the same directory as ButtonMain. This should be the default.

  • Add the Button.java file to the ButtonMain project.

  • Build and run the project. If you have bugs, you'll need to fix them.

• Exercise III: Building a Better Button
  • Add two additional fields to the Button class:
    • myLastPushedDate
    • myLastClearedDate
    These fields should be initialized with the creation time. (Each of these involves adding a single line to Button.java .)

  • Add two additional methods to the Button class:

    • GetWhenPushed

    • GetWhenCleared
    (Each of these will involve adding a few lines to Button.java .)

  • Add calls to ButtonMain to test the code that you have written.

  • Document Button.java.

   

  ---

  Last revision: September 16, 1999 at 9 am.