Find the most specialized class from group compatible with clazz. - Java Reflection

Java examples for Reflection:Class

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Description

Find the most specialized class from group compatible with clazz.

Demo Code

/*//from ww w . j  a  v  a 2s .c  o  m
 * Copyright (c) 2012 Data Harmonisation Panel
 * 
 * All rights reserved. This program and the accompanying materials are made
 * available under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the License,
 * or (at your option) any later version.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution. If not, see <http://www.gnu.org/licenses/>.
 * 
 * Contributors:
 *     HUMBOLDT EU Integrated Project #030962
 *     Data Harmonisation Panel <http://www.dhpanel.eu>
 */
//package com.java2s;

import java.util.Collection;

public class Main {
    /**
     * <p>
     * Find the most specialized class from group compatible with clazz. A
     * direct superclass match is searched and returned if found.
     * </p>
     * <p>
     * If not and checkAssignability is true, the most derived assignable class
     * is being searched.
     * </p>
     * <p>
     * See The Java Language Specification, sections 5.1.1 and 5.1.4 , for
     * details.
     * </p>
     * 
     * @param clazz a class
     * @param group a collection of classes to match against
     * @param checkAssignability whether to use assignability when no direct
     *            match is found
     * @return null or the most specialized match from group
     */
    public static Class<?> findMostSpecificMatch(Class<?> clazz,
            Collection<Class<?>> group, boolean checkAssignability) {
        if (clazz == null || group == null)
            throw new IllegalArgumentException(""); //$NON-NLS-1$

        // scale up the type hierarchy until we have found a matching class
        for (Class<?> c = clazz; c != Object.class; c = c.getSuperclass()) {
            if (group.contains(c))
                return c;
        }

        if (checkAssignability) {
            // in lieu of a direct match, check assignability (likely clazz is
            // an interface)
            Class<?> result = null;
            for (Class<?> c : group) {
                if (clazz.isAssignableFrom(c)) {
                    // result null or less specialized -> overwrite
                    if (result == null || result.isAssignableFrom(c))
                        result = c;
                }
            }
            return result;
        } else {
            return null;
        }
    }
}

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