1 files changed, 66 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/lang3/reflect/InheritanceUtils.java b/src/main/java/org/apache/commons/lang3/reflect/InheritanceUtils.java
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+++ b/src/main/java/org/apache/commons/lang3/reflect/InheritanceUtils.java
@@ -0,0 +1,66 @@
+/*
+ * 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)}.
+     *
+     * <p>This constructor is {@code public} to permit tools that require a JavaBean
+     * instance to operate.</p>
+     */
+    public InheritanceUtils() {
+    }
+
+    /**
+     * 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;
+    }
+}