public void checkCollision() {
		for (OperateShape shape : shapes) {
			if (shape instanceof Circle) {
				for (OperateShape checkShape : shapes) {
					event = new CollisionEvent();
					if (checkShape instanceof Circle) {
					} else if (checkShape instanceof Block) {
					} else if (checkShape instanceof Bar) {
					}

					if (isCollision) {
						event.addTarget(checkShape);
						event.addTarget(shape);
						
						notifyEvent(event);
						isCollision = false;	
					}
				}
			}
		}
	}