001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.lang3.reflect; 018 019import org.apache.commons.lang3.BooleanUtils; 020 021/** 022 * <p>Utility methods focusing on inheritance.</p> 023 * 024 * @since 3.2 025 */ 026public class InheritanceUtils { 027 028 /** 029 * <p>{@link InheritanceUtils} instances should NOT be constructed in standard programming. 030 * Instead, the class should be used as 031 * {@code MethodUtils.getAccessibleMethod(method)}.</p> 032 * 033 * <p>This constructor is {@code public} to permit tools that require a JavaBean 034 * instance to operate.</p> 035 */ 036 public InheritanceUtils() { 037 super(); 038 } 039 040 /** 041 * <p>Returns the number of inheritance hops between two classes.</p> 042 * 043 * @param child the child class, may be {@code null} 044 * @param parent the parent class, may be {@code null} 045 * @return the number of generations between the child and parent; 0 if the same class; 046 * -1 if the classes are not related as child and parent (includes where either class is null) 047 * @since 3.2 048 */ 049 public static int distance(final Class<?> child, final Class<?> parent) { 050 if (child == null || parent == null) { 051 return -1; 052 } 053 054 if (child.equals(parent)) { 055 return 0; 056 } 057 058 final Class<?> cParent = child.getSuperclass(); 059 int d = BooleanUtils.toInteger(parent.equals(cParent)); 060 061 if (d == 1) { 062 return d; 063 } 064 d += distance(cParent, parent); 065 return d > 0 ? d + 1 : -1; 066 } 067}