1. If your Lab6 was fully implemented having the RoundHeads move horizontally, then open your your Lab6 project in NetBeans, copy all of the files from the src folder, and paste them into the src folder of your new Lab8 project.
   
   
2. If your Lab6 project is not working or you didn't completely implement at least the move horizontally stuff, then right-click on the following file and save it:

   Lab8StarterFiles.zip

   Unzip and Extract All of the files, and copy ALL FOUR of the files you unzipped into the src folder of your project.
   
   

    private RoundHead[] rhArray;

    rhArray = new RoundHead[???];

    for (Integer index = 0; index < rhArray.length; index++) {

        rhArray[index] = new RoundHead( ?, ?, ?, ?, ?, ?, ?, ? );
	
    } // end of for loop

• the RoundHead should be HAPPY.  This means use true as the boolean parameter value in the constructor call.
• the RoundHead's hat should be RED.
• over should be a formula that computes 30 times the loop control variable.  The loop control variable is what is being initialized, tested and changed inside the parentheses of the for loop.
• down should be should be a formula that computes 20 times the loop control variable.
• the verticalStepSize should be 15.
• the horizontalStepSize should be 10.
• the size should be 25
• the nickName should be "Sammy"
  
  

In your browser right click on:

• Star.java
  

and choose Save Target As... and save the file in the src folder of your project. 

    private Random randGenerator = new Random();

• declare two Integer variables called x and y
• set x to a random integer in the range from 0 to 590
• set y to a random integer in the range from 0 to 390
• instantiate one element of the array, using x and y as the two parameters that are passed into the Star constructor method.

    randNum = randGenerator.nextInt(upper);

Put lines similar to this one inside the for loop to store random numbers into x and y.

In the paintComponent method of the MUPanel.java file, write code that uses a loop to call the draw method of each Star object in the array.  Place the loop that draws the stars BEFORE you draw the RoundHeads in the paintComponent method.

If you run the program now, you won't see any stars, because they are white, and they are being drawn on a white background.  Change the program so that the background of the output window is Color.BLACK, and run the program.

Add two new methods to MUPanel.java, as follows.  The first method is named "moveGeorge", and it is a void method that accepts no parameters.  In the moveGeorge method, call the moveVertically method and also the moveHorizontally method for the george object.  The second method is named "changeGeorgesMood", and it also is a void method that accepts no parameters.  The changeGeorgesMood method should call the changeMood method for the george object.

Switch to MUFrame.java in the editor, and change to "Design" mode.  Add two new buttons to the interface, one labeled "Move George" and the other named "Change George's Mood".  The actionPerformed methods for these two buttons should call the appropriate methods of the muPanel object that you wrote in the previous instruction, and then ask muPanel to repaint().  Test the program now, and the new buttons should cause George to move or change mood while the other RoundHeads remain stationary.

Now let's modify MUPanel so that the RoundHeads in the array move on the screen even if we aren't clicking the Move Roundheads button.  To do this, start by modifying the class heading for the MUPanel class so that it looks like this:

public class MUPanel extends JPanel implements Runnable {

    private volatile Thread animator;
    private Integer animationDelay = 200;
 
    public void start() {
        if (animator == null) {
            animator = new Thread(this);
            animator.start();
        } // end if
    } // end of start()

    public void stop() {
        animator = null;
    } // end of stop()
  
    public void run() {
        Thread thisThread = Thread.currentThread();
        while (animator == thisThread) {
            moveObjects();
            repaint();
			
            try { Thread.sleep(animationDelay); }
            catch (InterruptedException e) { }
        } // end while
    } // end of run()
	

If you would want the animation to start as soon as the program starts, there is a simple way to do that.  In MUFrame.java, scroll to the end of the constructor method, and then right before the closing brace for the method, call the muPanel.start() method.  The constructor is executed only once, when the program starts, and so the animation will begin right away instead of waiting for the user to click the Start Animation button.  You should be able to stop and start the animation with the buttons as before.

The variable named animationDelay specifies the delay that will be used between repaintings, and is a number of milliseconds (thousandths of a second).  You can make the animation effects happen faster by using a smaller number for the animation delay, or slow it down with a bigger number for the delay.  Try changing the value of animationDelay in MUPanel.java, using 500 (which is a ½ second delay), then try 100 (a tenth-of-a-second delay), and finally try 25 — that's really fast!  Change the delay a final time to a value that you like.

Add randomness to the instantiation of the RoundHead objects in your program so that the horizontal and vertical movement factors used for each RoundHead in the array is a random integer in the range from -30 to 30.  Run the program and watch the RoundHeads break out of their initial positions unpredictably.

You could add a button or two to the interface to increase or decrease the animationDelay value to speed up or slow down the animation as it is running.  To do that, you would need a setAnimationDelay method in MUPanel that could be called from the actionPerformed methods in MUFrame.  Or maybe you would like to try a Spinner or a Slider for changing the animationDelay....