问我正确地使用了静态吗？

EN

public class SignManager
{
    private static HashMap<String, List<GameSign>> signsBySection   = new HashMap<>();
    private static HashMap<String, List<GameServer>> serversBySection = new HashMap<>();
    private static HashMap<String, GameServer>serverNames = new HashMap<>();
    private static HashMap<Sign, GameSign> gameSignBySign = new HashMap<>();
    private static List<GameServer> availableServers = new ArrayList<>();
    private static List<GameServer> displayedServers = new ArrayList<>();

    public static void addSign(String section, Sign sign)
    {
        List<GameSign> signs = signsBySection.get(section);

        if(signs == null)
            signsBySection.put(section, signs = new ArrayList<>());

        GameSign gameSign = new GameSign(section, sign.getLocation());

        signs.add(gameSign);
        gameSignBySign.put(sign, gameSign);
    }

    public static void addServers(String section, List<String> range)
    {
        List<GameServer> servers = SignManager.serversBySection.get(section);

        if(servers == null)
            SignManager.serversBySection.put(section, servers = new ArrayList<>());

        for(String s : range)
        {
            GameServer server = new GameServer(s);

            servers.add(server);
            serverNames.put(s, server);
        }
    }

    public static void setAvailable(GameServer server)
    {
        availableServers.add(server);
    }

    public static void replaceDisplayed(GameServer old, GameServer newServer)
    {
        removeDisplayed(old);
        displayedServers.add(newServer);
    }

    public static void removeDisplayed(GameServer server)
    {
        displayedServers.remove(server);

        if(server != null)
            server.setSign(null);
    }

    public static boolean isDisplayed(GameServer server)
    {
        return displayedServers.contains(server);
    }

    public static boolean isAvailable(GameServer server)
    {
        return availableServers.contains(server);
    }

    public static void tick()
    {
        for(GameSign sign : getAllGameSigns())
            sign.tick();

        GameSign.addDot();
    }

    public static GameServer getGameServer(String name)
    {
        return serverNames.get(name);
    }

    public static GameServer getNextAvailableServer()
    {
        if(availableServers.size() == 0)
            return null;

        GameServer server = availableServers.get(0);
        availableServers.remove(0);
        return server;
    }

    public static GameSign getGameSign(Sign sign)
    {
        return gameSignBySign.get(sign);
    }

    public static Set<Map.Entry<String, List<GameSign>>> getSignsBySection()
    {
        return signsBySection.entrySet();
    }

    public static Collection<GameServer> getAllServers()
    {
        return serverNames.values();
    }

    public static Collection<GameSign> getAllGameSigns()
    {
        return gameSignBySign.values();
    }
}