2 * Reactor - State.java - Copyright © 2013 David Roden
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 3 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 package net.pterodactylus.reactor;
21 * Defines the current state of a system.
23 * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
25 public interface State {
28 * Whether the state was successfully retrieved. This method should only
29 * return {@code true} if a meaningful result could be retrieved; if e. g. a
30 * service is currently not reachable, this method should return false
31 * instead of emulating success by using empty lists or similar constructs.
33 * @return {@code true} if the state could be retrieved successfully,
34 * {@code false} otherwise
39 * If {@link #success()} returns {@code false}, this method may return a
40 * {@link Throwable} to give some details for the reason why retrieving the
41 * state was not possible. For example, network-based {@link Query}s might
42 * return any exception that were encountered while communicating with the
45 * @return An exception that occured, may be {@code null} in case an
46 * exception can not be meaningfully returned
48 Throwable exception();