public class Square {
    private int size;        // The side of a side of the square
    private int xPosition;   // The x,y coordinates of its top left corner
    private int yPosition;
    private String color;    // The color of the square

    // Create a new square
    public Square(int xPosition, int yPosition, int size, String color) {
        this.xPosition = xPosition;
        this.yPosition = yPosition;
        this.size      = size;
        this.color     = color;
        draw();
    }

    // Move the square to a new position.
    public void moveTo(int newX, int newY) {
		erase();
		this.xPosition = newX;
		this.yPosition = newY;
		draw();
    }

    // Move the square by an amount.
    public void move(int deltaX, int deltaY) {
		erase();
		this.xPosition = this.xPosition + deltaX;
		this.yPosition = this.yPosition + deltaY;
		draw();
    }

    // Change the side to the new side.
    public void changeSize(int newSize) {
		erase();
		this.size = newSize;
		draw();
    }

    // Change the color.
    // Valid colors are "red","yellow","blue","green","magenta" and "black".
    public void changeColor(String newColor) {
		erase();
		this.color = newColor;
		draw();
    }

    // Draw the square with current specifications on screen.
    private void draw() {
        Canvas canvas = Canvas.getCanvas();
        canvas.setForegroundColour(this.color);
        canvas.fill(new java.awt.Rectangle(this.xPosition, this.yPosition, this.size, this.size));
        canvas.wait(50);
    }

    // Erase the square on screen.
    public void erase() {
        Canvas canvas = Canvas.getCanvas();
        canvas.erase(new java.awt.Rectangle(this.xPosition, this.yPosition, this.size, this.size));
    }
}