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  * Copyright 2010-2015, Inc. or its affiliates. All Rights Reserved.
  * Portions copyright 2006-2009 James Murty. Please see LICENSE.txt
  * for applicable license terms and NOTICE.txt for applicable notices.
  * Licensed under the Apache License, Version 2.0 (the "License").
  * You may not use this file except in compliance with the License.
  * A copy of the License is located at
 * or in the "license" file accompanying this file. This file is distributed
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
package com.amazonaws.util;
Classes related utilities.
public enum Classes {
Returns the class of the immediate subclass of the given parent class for the given object instance; or null if such immediate subclass cannot be uniquely identified for the given object instance.

parentClass the parent class. The child class is java.lang.Object if and only if the parent class is null.
instance the given object instance
    public static Class<?> childClassOf(Class<?> parentClass,
            Object instance) {
        if (instance == null || instance == Object.class)
            return null;
        if (parentClass != null) {
            if (parentClass.isInterface()) {
                // child of an interface class is not injective (ie one-to-one)
                return null;
        Class<?> childClass = instance.getClass();
        while (true) {
            Class<?> parent = childClass.getSuperclass();
            if (parent == parentClass)
                return childClass;
            if (parent == null)
                return null;
            childClass = parent;

Returns the jar file from which the given class is loaded; or null if no such jar file can be located.
    public static JarFile jarFileOf(Class<?> klass) {
        URL url = klass.getResource(
            "/" + klass.getName().replace('.''/') + ".class");
        if (url == null)
            return null;
        String s = url.getFile();
        int beginIndex = s.indexOf("file:") + "file:".length();
        int endIndex = s.indexOf(".jar!");
        if (endIndex == -1)
            return null;
        endIndex += ".jar".length();
        String f = s.substring(beginIndexendIndex);
        File file = new File(f);
        try {
            return file.exists() ? new JarFile(file) : null;
        } catch (IOException e) {
            throw new IllegalStateException(e);
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