Software Engineering for Students A Programming Approach

Figure 15.1 Cyberspace invaders
15.2 Encapsulation 201
the screen – an alien, a laser, a bomb and the user. We will represent each of these as
an object.
We will represent the alien as an object, but to create an object, we have to write a
class (a blueprint for any number of aliens). In Java, we write the class as follows:
class Alien {
private int x, y;
private int size;
private ImageIcon alienImage;
public Alien(int newX, int newY, int newSize) {
x = newX;
y = newY;
size = newSize:
alienImage = new ImageIcon("c:/alien.jpg");
}
public void display(JPanel panel) {
Graphics paper = panel.getGraphics();
alienImage.paintIcon(panel, paper, x, y);
}
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