Java Reference
In-Depth Information
11.5 Drawing the Stickmen
Next, we will add code that keeps track of the number of lives. Let us first start with
the Player class that keeps track of the number of available lives and draws stickmen for
import java .awt . ;
import java. io .File ;
import javax . imageio .ImageIO;
public class Player {
private static int INITIAL NUM LIVES = 3 ;
private static int IMAGE Y POSITION = 450;
private static int IMAGE H GAP = 5 ;
private int numLives ;
public Player () {
this . numLives = INITIAL NUM LIVES ;
public void killPlayer()
numLives −− ;
public boolean isAlive()
return (numLives
0) ;
public void draw(Graphics2D g2)
try {
Image image = ImageIO. read ( new File( "player.gif" ));
for ( int x=0;x < numLives ; x++) {
g2 . drawImage( image , x (image . getWidth( null )+IMAGEH GAP) ,
catch (Exception newException) {
The code starts with 3 lives, where this number is saved in a constant and can be
changed. The killPlayer method removes a life, while the isAlive method reports on
whether there are lives left. Note that this is an excellent example of data encapsulation
because the world outside the class does not know how many lives are left. It does not know
because it does not need to know. As is the case in the CIA, information between classes
should be shared only on a need-to-know basis. The less information that is shared, the
easier it is to identify erroneous code.
The draw method draws a stickman for each available life. In our code, the image of
a stickman is saved in player.gif . Feel free to create your own image. Depending on the
size of the image, the variable IMAGE Y POSITION mayhavetobemodified.Notethatthe
method has a try-catch block, which is formally explained in Chapter 13. The reason is
that the code can raise an exception if the file player.gif does not exist. The code does
nothing to handle the exception.
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