CPSC 170 Lab 2
Array Lists, Inheritance, and Mouse Listeners

ArrayLists

1. The code has been commented in Javadoc style. Generate the javadoc for the PileOfCards code to generate the html description of the class. Study the HTML file and make not of the following:
   • There are multiple places that identify the lineage of pileofCards. In this case, it is pretty simple - it is a child of java.lang.Object. However, in more complicated objects, this document would tell you the entire list of what other classes this class is decended from.
   • Along the same lines, notice that there is a listing of the methods that this object has inherited (from object). Remember in class, we talked about how the Object class has a toString method? Why does pileOfCards not inherit the toString Method from Object?
   • Some of the comments have questions - you should answer them before writing any code. A good practice to get into is to understand the design of a class and how it works as much as possible before you try to implement it. (It helps to have the comments and the skeleton fleshed out like this). Doing this not only clarifies the tasks ahead for you, it also makes it easier to verify that your code will work properly, and saves you from recoding portions of your program as you redesign on the fly.

2. Implement the pileOfCards class according to the specifications in its JavaDoc.

3. If you have thought about it correctly, you should be confident that pileOfCards is free of logic and run-time errors. If you are not confident, take a few moments to think about where you may have gone wrong and convince yourself that it is correct. Make any changes that you feel are necessary.

4. If you skipped over step 3, because there was nothing to type, you'll regret it in the long run - I'm serious - stop and think about your code for a second.

5. When you are confident that your code is correct, write a text-based driver program to verifies that your pileOfCards code works correctly. (Make sure that your this program will convince me! P.S. there is nothing "random" about this program). The output of your program should include statements or what condition is being checked, the anticipated outcome of this statement and the actual outcome of this statement. Observe: It is not acceptable for the PileOfCards class to generate any run-time errors - all "bad" conditions should be gracefully dealt with.

6. Write a graphical driver program that interacts with a pile of cards. The file CardGame.java contains a simple stub for a JFrame that contains a CardPanel (which is-a JPanel). You will need to update the CardPanel class with the following changes:
   • Add a pile of cards containing one of each of the cards that can be created. (i.e. a complete deck)
   • Add a JLabel that displays the image of card most recently removed from the pile. If no cards have been removed - display the BlankIcon (see the Card class). The file GPLcards.tgz contains the images used by the card class. You will need to untar the file in your Labs directory (tar xzf GPLcards.tgz). Verify that a new directory (GPLCards) was created in Labs and that the Card class is looking in the correct location for the files.
   • Add a button that, when pressed, removes a card from the pile and updates the icon on the JLabel.
   • After all the cards have been displayed, if the user presses the button again, you should pop-up a messagebox indicating that there are no more cards.

       
     JOptionPane.showMessageDialog(null, "No More Cards");
     

Inheritance

In essence we are saying, "do what the parent does.... plus a little more".

We often see this used with constructors - the initial configuration is the same as the parent, but we also are concerned about initializing data that is unique to the child class. Since this is such a common occurrence, the constructor for a child class implicitly invokes the parent's constructor if there is not an explicit call to the constructor.. To see this in action, download ClassA.java, ClassB.java and ABInherit.java After looking at the code, compile and execute ABInherit.java - Does it do what you expected?

Inheritance with methods

File DogTest.java contains a simple driver program that creates a dog and makes it speak. Study DogTest.java, save it to your directory, and then run it to confirm what it does.

The file Yorkshire.java contain declarations for a class that extend Dog. Save and study this files as well. Modify DogTest.java to add statements to add and print a Yorkshire (also make it speak).

The file Labrador.java also extends the Dog class. However, note that the Labrador constructor takes two parameters: the name and color of the labrador, both strings. Notice that this class contains an error:

Implicit super constructor Dog() is undefined

Add code to DogTest.java to print the average breed weight for both your Labrador and your Yorkshire. Use the avgBreedWeight() method for both. Look at the error that you get. Figure out what is wrong and fix the problem by adding the needed code to the Yorkshire class.

Print DogTest.java, Dog.java, Labrador.java, and Yorkshire.java to turn in.

Mouse Events

1. File MousePlay.java contains a program that displays a message saying when the mouse button is pressed and released. It uses MousePlayPanel.java to define the JPanel that is actually displayed. Save these files to your directory, open them in Eclipse, and run MousePlay to see how it works. Note that MousePlayPanel has an inner class MousePlayListener that implements MouseListener by giving bodies for the five MouseListener methods. Even though nothing is done when the mouse is clicked or when it enters or exits, those methods still appear with empty bodies -- this is required for the MouseListener interface to be implemented.

   Modify MousePlayPanel so that it also prints appropriate messages when the mouse is clicked, when it enters the panel, and when it exits. Play with the resulting program until you understand how the mouse events are generated.

2. Files Dots.java and DotsPanel.java contain revised versions of the code in listings 7.18 and 7.19 in the text. Dots draws a dot every time the uses presses the mouse button; only the current dot is shown in the revised version. Save these files to your directory and run Dots to see how it works. Then modify DotsPanel as follows:
   1. Make the dots that appear alternately red and green. To do this, you will need to make the following changes:
      • Add an instance variable to hold the dot color.
      • Add an instance variable to count the number of dots that have been drawn.
      • When the mouse is pressed, in addition to setting the draw point you need to update the counter and change the dot color to green if the counter is odd, to red if it is even. Then call repaint.
   2. Modify your code so that the dot is drawn where the mouse is released, not where it is pressed.

   Print DotsPanel.java to turn in.

   HAND IN:

   • Printouts of the files that you made changes to. Make sure that your name is included in the header comments (not just written on)
   • Tar the files in your lab2 directory with the command

      
     tar czf lab2.tgz . 
     

   • send the tar file to me via e-mail.