Go to Center

This program animates a square that moves until it is in the center of the screen. It starts on the left side.

Solution

public class GoCenter extends GraphicsProgram {

    private static final int SIZE = 20;
    private static final int DELAY = 100;
	
	public void run() {
		// Draw a square on the left of the screen.
		GRect rect = new GRect(SIZE, SIZE);
		double x = 0;
		double y = (getHeight() - rect.getHeight()) / 2;
		rect.setFilled(true);
		add(rect, x, y);
		
		// Move until the center
		// rect.getX() returns the x coordinate of the rectangle
		double maxX = (getWidth() - rect.getWidth()) /2;
		while(rect.getX() < maxX) {
		    // move one pixel to the right
			rect.move(1, 0);
			// animation pause.
			pause(DELAY);
		}
	}
}