# Fehler behandeln { #handling-errors }

Es gibt viele Situationen, in denen Sie einem Client, der Ihre API nutzt, einen Fehler mitteilen müssen.

Dieser Client könnte ein Browser mit einem Frontend sein, ein Code von jemand anderem, ein IoT-Gerät usw.

Sie könnten dem Client mitteilen müssen, dass:

* Der Client nicht genügend Berechtigungen für diese Operation hat.
* Der Client keinen Zugriff auf diese Ressource hat.

- Kube-apiserver: Get, GetList and Watch requests that should be served by the apiserver cacher during shutdown will be rejected to avoid a deadlock situation leaving requests hanging. ([#108414](https://github.com/kubernetes/kubernetes/pull/108414), [@aojea](https://github.com/aojea))

   * {@link SortedMultiset#tailMultiset}, the {@code size()} and {@code iterator()} methods of
   * {@link SortedMultiset#entrySet}, and {@link SortedMultiset#remove(Object, int)}. In many
   * situations, you may wish to override {@link SortedMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   */
  protected class StandardElementSet extends SortedMultisets.ElementSet<E> {

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS or "Cross-Origin Resource Sharing"</a> refers to the situations when a frontend running in a browser has JavaScript code that communicates with a backend, and the backend is in a different "origin" than the frontend.

## Origin { #origin }

   * {@link SortedMultiset#tailMultiset}, the {@code size()} and {@code iterator()} methods of
   * {@link SortedMultiset#entrySet}, and {@link SortedMultiset#remove(Object, int)}. In many
   * situations, you may wish to override {@link SortedMultiset#elementSet} to forward to this
   * implementation or a subclass thereof.
   *
   * @since 15.0
   */

         * Therefore, we can always create our own TypeVariable. (One downside of our TypeVariable
         * in some situations is that it does not support the AnnotatedType API. However, those
         * situations don't arise under Android because Android does not provide the AnnotatedType
         * API at all.)
         *

There may be many routes for a single address. For example, a webserver that is hosted in multiple datacenters may yield multiple IP addresses in its DNS response.

In limited situations OkHttp will retry a route if connecting fails:

Several of these are explored in the next chapters of the tutorial.

## Order matters { #order-matters }

When creating *path operations*, you can find situations where you have a fixed path.

Like `/users/me`, let's say that it's to get data about the current user.

And then you can also have a path `/users/{user_id}` to get data about a specific user by some user ID.

testing everything. You can even copy & paste HTTP responses from your real web
server to create representative test cases. Or test that your code survives in
awkward-to-reproduce situations like 500 errors or slow-loading responses.


### Example

Use MockWebServer the same way that you use mocking frameworks like
[Mockito](https://github.com/mockito/mockito):

1. Script the mocks.

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS oder <abbr title="Ressourcenfreigabe zwischen Ursprüngen">„Cross-Origin Resource Sharing“</abbr></a> bezieht sich auf Situationen, in denen ein Frontend, das in einem Browser läuft, JavaScript-Code enthält, der mit einem Backend kommuniziert, und das Backend sich in einem anderen „Origin“ als das Frontend befindet.

## Origin { #origin }