public class Ball {
	protected int x,y;
	protected String color;
	public Ball(String color){
		this.color = color;
		x=0; y=0;
	}
	public void move(int dx, int dy){
		x+=dx; y+=dy;
	}
	public String toString(){
		return color + " ball at (" + x +
				"," + y + ")";
	}
	
	public boolean equals(Object obj){
		if (obj == null) // 1
			return false;
		if (obj == this) // 2
			return true;
		if ( !(obj instanceof Ball) ) // 3
			return false;
		if ( !super.equals(obj) ) // 4
			return false;
		Ball other = (Ball)obj;
		return // 5
			this.x == other.x &&
			this.y == other.y;
	}
	public boolean equals2(Object obj){
		try{
			Ball other = (Ball)obj;
			return // 5
				this.x == other.x &&
				this.y == other.y;
		}catch(Exception wrong){
			return false;
		}
	}

	
	
	public static void main(String[] args){
		Ball b1;
		Ball b2 = new Ball("Red");
		b2.move(5,10);
		System.out.println(b2);
		b1 = b2;
		b1.move(3,2);
		System.out.println(b2);
		b1 = new Ball("Green");
		b1.move(2,4);
		System.out.println(b2);
	}

}