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 package org.apache.logging.log4j.core.util;
18
19 import java.util.Collection;
20 import java.util.Map;
21
22 /**
23 * Utility class providing common validation logic.
24 */
25 public final class Assert {
26 private Assert() {
27 }
28
29 /**
30 * Checks if an object has empty semantics. The following scenarios are considered empty:
31 * <ul>
32 * <li>{@code null}</li>
33 * <li>empty {@link CharSequence}</li>
34 * <li>empty array</li>
35 * <li>empty {@link Iterable}</li>
36 * <li>empty {@link Map}</li>
37 * </ul>
38 *
39 * @param o value to check for emptiness
40 * @return true if the value is empty, false otherwise
41 * @since 2.8
42 */
43 public static boolean isEmpty(final Object o) {
44 if (o == null) {
45 return true;
46 }
47 if (o instanceof CharSequence) {
48 return ((CharSequence) o).length() == 0;
49 }
50 if (o.getClass().isArray()) {
51 return ((Object[]) o).length == 0;
52 }
53 if (o instanceof Collection) {
54 return ((Collection<?>) o).isEmpty();
55 }
56 if (o instanceof Map) {
57 return ((Map<?, ?>) o).isEmpty();
58 }
59 return false;
60 }
61
62 /**
63 * Opposite of {@link #isEmpty(Object)}.
64 *
65 * @param o value to check for non-emptiness
66 * @return true if the value is non-empty, false otherwise
67 * @since 2.8
68 */
69 public static boolean isNonEmpty(final Object o) {
70 return !isEmpty(o);
71 }
72
73 /**
74 * Checks a value for emptiness and throws an IllegalArgumentException if it's empty.
75 *
76 * @param value value to check for emptiness
77 * @param <T> type of value
78 * @return the provided value if non-empty
79 * @since 2.8
80 */
81 public static <T> T requireNonEmpty(final T value) {
82 return requireNonEmpty(value, "");
83 }
84
85 /**
86 * Checks a value for emptiness and throws an IllegalArgumentException if it's empty.
87 *
88 * @param value value to check for emptiness
89 * @param message message to provide in exception
90 * @param <T> type of value
91 * @return the provided value if non-empty
92 * @since 2.8
93 */
94 public static <T> T requireNonEmpty(final T value, final String message) {
95 if (isEmpty(value)) {
96 throw new IllegalArgumentException(message);
97 }
98 return value;
99 }
100
101 public static int valueIsAtLeast(final int value, final int minValue) {
102 if (value < minValue) {
103 throw new IllegalArgumentException("Value should be at least " + minValue + " but was " + value);
104 }
105 return value;
106 }
107 }