public boolean validTileLoc(int x, int y)
	// Is tile coord (x,y) on the tile map and not contain an obstacle?
	{
		if ((x < 0) || (x >= numXTiles) || (y < 0) || (y >= numYTiles))
			return false;
		if (obstacles[x][y])
			return false;
		return true;
	} // end of validTileLoc()