1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17
18 package org.apache.logging.log4j.util;
19
20 import org.apache.logging.log4j.message.Message;
21
22 /**
23 * Classes implementing this interface know how to supply {@link Message}s.
24 *
25 * <p>This is a <a href="https://docs.oracle.com/javase/8/docs/api/java/util/function/package-summary.html">functional
26 * interface</a> intended to support lambda expressions in log4j 2.
27 *
28 * <p>Implementors are free to cache values or return a new or distinct value each time the supplier is invoked.
29 *
30 * <p><strong>DEPRECATED:</strong> this class should not normally be used outside a Java 8+ lambda syntax. Instead,
31 * {@link Supplier Supplier<Message>} should be used as an anonymous class. Both this and {@link Supplier} will be
32 * removed in 3.0.
33 * </p>
34 *
35 * @since 2.4
36 */
37 public interface MessageSupplier {
38
39 /**
40 * Gets a Message.
41 *
42 * @return a Message
43 */
44 Message get();
45 }