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.commons.lang3.reflect;
18
19 import org.apache.commons.lang3.BooleanUtils;
20
21 /**
22 * Utility methods focusing on inheritance.
23 *
24 * @since 3.2
25 */
26 public class InheritanceUtils {
27
28 /**
29 * Returns the number of inheritance hops between two classes.
30 *
31 * @param child the child class, may be {@code null}
32 * @param parent the parent class, may be {@code null}
33 * @return the number of generations between the child and parent; 0 if the same class;
34 * -1 if the classes are not related as child and parent (includes where either class is null)
35 * @since 3.2
36 */
37 public static int distance(final Class<?> child, final Class<?> parent) {
38 if (child == null || parent == null) {
39 return -1;
40 }
41
42 if (child.equals(parent)) {
43 return 0;
44 }
45
46 final Class<?> cParent = child.getSuperclass();
47 int d = BooleanUtils.toInteger(parent.equals(cParent));
48
49 if (d == 1) {
50 return d;
51 }
52 d += distance(cParent, parent);
53 return d > 0 ? d + 1 : -1;
54 }
55
56 /**
57 * {@link InheritanceUtils} instances should NOT be constructed in standard programming.
58 * Instead, the class should be used as
59 * {@code MethodUtils.getAccessibleMethod(method)}.
60 *
61 * <p>This constructor is {@code public} to permit tools that require a JavaBean
62 * instance to operate.</p>
63 */
64 public InheritanceUtils() {
65 }
66 }