![Events Diagram](../assets/images/events@2x.png)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.sse.internal

internal data class Event(
  val id: String?,
  val type: String?,
  val data: String,

  }

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertOpen(): WebSocket {
    val event = nextEvent() as Open
    return event.webSocket
  }

  fun assertFailure(t: Throwable?) {
    val event = nextEvent() as Failure
    assertThat(event.response).isNull()
    assertThat(event.t).isSameAs(t)
  }

  fun assertFailure(

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertEvent(
    id: String?,
    type: String?,
    data: String,
  ) {
    assertThat(nextEvent()).isEqualTo(Event(id, type, data))
  }

  fun assertOpen(): EventSource {
    val event = nextEvent() as Open
    return event.eventSource
  }

  fun assertClose() {
    nextEvent() as Closed
  }

  fun assertFailure(

   *
   * @param executor Executor to use to dispatch events. It is the caller's responsibility to shut
   *     down the executor after the last event has been posted to this event bus.
   * @param subscriberExceptionHandler Handler used to handle exceptions thrown from subscribers.
   *     See {@link SubscriberExceptionHandler} for more information.
   * @since 16.0
   */

    }

    /**
     * Rewrites log events by converting ERROR level to WARN level for matching loggers.
     *
     * @param event the log event to potentially rewrite
     * @return the original event or a new event with WARN level if conversion applied
     */
    @Override
    public LogEvent rewrite(final LogEvent event) {
        final String loggerName = event.getLoggerName();
        if (loggerName == null) {

      throw AssertionError("full event sequence: $fullEventSequence", e)
    }
  }

  /**
   * Remove and return the next event from the recorded sequence.
   *
   * @param eventClass a class to assert that the returned event is an instance of, or null to
   *     take any event class.
   * @param elapsedMs the time in milliseconds elapsed since the immediately-preceding event, or
   *     -1L to take any duration.
   */

  /**
   * Invoked when an event source has been accepted by the remote peer and may begin transmitting
   * events.
   */
  open fun onOpen(
    eventSource: EventSource,
    response: Response,
  ) {
  }

  /**
   * Invoked when a new event has been sent to the client.
   *
   * @param id The `id` line of the event, might be null.
   * @param type The `event` line of the event, might be null.

public class StringCatcher {
  private final List<String> events = new ArrayList<>();

  @Subscribe
  public void hereHaveAString(@Nullable String string) {
    events.add(string);
  }

  public void methodWithoutAnnotation(@Nullable String string) {
    Assert.fail("Event bus must not call methods without @Subscribe!");
  }

  public List<String> getEvents() {
    return events;
  }

  }

  /**
   * Enqueues an event to be run on currently known listeners.
   *
   * <p>The {@code toString} method of the Event itself will be used to describe the event in the
   * case of an error.
   *
   * @param event the callback to execute on {@link #dispatch}
   */
  public void enqueue(Event<L> event) {
    enqueueHelper(event, event);
  }

  /**