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.commons.lang3.function;
19
20 import java.util.function.Supplier;
21
22 /**
23 * Helps use {@link Supplier}.
24 *
25 * @since 3.13.0
26 */
27 public class Suppliers {
28
29 /**
30 * Returns the singleton supplier that always returns null.
31 * <p>
32 * This supplier never throws an exception.
33 * </p>
34 */
35 @SuppressWarnings("rawtypes")
36 private static Supplier NUL = () -> null;
37
38 /**
39 * Null-safe call to {@link Supplier#get()}.
40 *
41 * @param <T> the type of results supplied by this supplier.
42 * @param supplier the supplier or null.
43 * @return Result of {@link Supplier#get()} or null.
44 */
45 public static <T> T get(final Supplier<T> supplier) {
46 return supplier == null ? null : supplier.get();
47 }
48
49 /**
50 * Returns the singleton supplier that always returns null.
51 * <p>
52 * This supplier never throws an exception.
53 * </p>
54 *
55 * @param <T> Supplied type.
56 * @return The NUL singleton.
57 * @since 3.14.0
58 */
59 @SuppressWarnings("unchecked")
60 public static <T> Supplier<T> nul() {
61 return NUL;
62 }
63
64 /**
65 * Make private in 4.0.
66 *
67 * @deprecated TODO Make private in 4.0.
68 */
69 @Deprecated
70 public Suppliers() {
71 // empty
72 }
73 }