org.apache.commons.lang3.reflect.InheritanceUtils Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of commons-lang3 Show documentation

Apache Commons Lang, a package of Java utility classes for the classes that are in java.lang's hierarchy, or are considered to be so standard as to justify existence in java.lang. The code is tested using the latest revision of the JDK for supported LTS releases: 8, 11, 17 and 21 currently. See https://github.com/apache/commons-lang/blob/master/.github/workflows/maven.yml Please ensure your build environment is up-to-date and kindly report any build issues.

There is a newer version: 3.17.0

Show newest version

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3.reflect;

import org.apache.commons.lang3.BooleanUtils;

/**
 * Utility methods focusing on inheritance.
 *
 * @since 3.2
 */
public class InheritanceUtils {

    /**
     * {@link InheritanceUtils} instances should NOT be constructed in standard programming.
     * Instead, the class should be used as
     * {@code MethodUtils.getAccessibleMethod(method)}.
     *
     * This constructor is {@code public} to permit tools that require a JavaBean
     * instance to operate.
     */
    public InheritanceUtils() {
        super();
    }

    /**
     * Returns the number of inheritance hops between two classes.
     *
     * @param child the child class, may be {@code null}
     * @param parent the parent class, may be {@code null}
     * @return the number of generations between the child and parent; 0 if the same class;
     * -1 if the classes are not related as child and parent (includes where either class is null)
     * @since 3.2
     */
    public static int distance(final Class child, final Class parent) {
        if (child == null || parent == null) {
            return -1;
        }

        if (child.equals(parent)) {
            return 0;
        }

        final Class cParent = child.getSuperclass();
        int d = BooleanUtils.toInteger(parent.equals(cParent));

        if (d == 1) {
            return d;
        }
        d += distance(cParent, parent);
        return d > 0 ? d + 1 : -1;
    }
}