我有哈希映射：private final ConcurrentHashMap<String, List<Client>> clients;和班級：public static class Client {    private String name; // it is also the key of the map    private String url;}我從多個線程中調(diào)用線程安全方法“ removeElement ”，該方法必須從列表中刪除一個值。@Overridepublic CompletableFuture<Void> removeClient(Client client) {    return CompletableFuture.runAsync(() ->            clients.entrySet().removeIf(v ->                    v.getValue().removeIf(                            it -> client.url.equals(it.url))            )    );}但當(dāng)然，這是行不通的。當(dāng)我得到 Method throws 'java.lang.UnsupportedOperationException' 異常時，我解決了這樣的問題：@Overridepublic CompletableFuture<Void> removeClient(Client client) {    return CompletableFuture.runAsync(() -> {                List<Client> currentClients = new ArrayList<>(clients.get(client.getName()));                currentClients.remove(client);                if (currentClients.isEmpty()) {                    clients.remove(client.getName());                } else {                    clients.put(client.getName(), currentClients);                }            }    );}但它不是線程安全的。我怎樣才能在這里實(shí)現(xiàn)它？也許有更優(yōu)雅的方法來解決它？