public void rollBack() {
		clear();
		if (excecuteHistory == MOVE_DOWN) {
			currentY--;
		} else if (excecuteHistory == MOVE_LEFT) {
			currentX++;
		} else if (excecuteHistory == MOVE_RIGHT) {
			currentX--;
		} else if (excecuteHistory == ROTATE_CLOCKWISE) {
			shape.rotate(false);
		} else if (excecuteHistory == ROTATE_COUNTERCLOCKWISE) {
			shape.rotate(true);
		}
		excecuteHistory = 0;
		setShapeInMatrix();
	}