Get a member using a getter method, or if there isn't any, try to retry it via member access if it's public. - Java Reflection

Java examples for Reflection:Getter

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Description

Get a member using a getter method, or if there isn't any, try to retry it via member access if it's public.

Demo Code

/**//from w ww.  j a  va 2 s.c  o  m
 * Copyright (c) 2003-2009, Xith3D Project Group all rights reserved.
 * 
 * Portions based on the Java3D interface, Copyright by Sun Microsystems.
 * Many thanks to the developers of Java3D and Sun Microsystems for their
 * innovation and design.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the 'Xith3D Project Group' nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) A
 * RISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE
 */
import java.lang.reflect.Method;

public class Main{
    public static void main(String[] argv) throws Exception{
        Object object = "java2s.com";
        String member = "java2s.com";
        System.out.println(get(object,member));
    }
    /**
     * Get a member using a getter method, or if there isn't any,
     * try to retry it via member access if it's public.
     * 
     * @param object
     *                The object from which to get the member
     * @param member
     *                The member to get
     * @return The value of the member asked for, or null if there's no getter
     */
    public static Object get(Object object, String member) {

        Object value = null;

        try {
            // Try to find a getter
            Method met = getGetter(object, member);
            value = met.invoke(object, (Object[]) null);
        } catch (NoGetterException e) {
            try {
                // If impossible, try to return it via member access
                value = object.getClass().getField(member).get(object);
            } catch (NoSuchFieldException ex) {
                throw new Error(
                        "Could not find either a getter or a field named "
                                + member + " in object of type "
                                + object.getClass().getSimpleName());
            } catch (Exception ex) {
                throw new Error(e);
            }
        } catch (Exception e) {
            throw new Error(e);
        }

        return value;

    }
    /**
     * Finds the appropriate the getter for an Object.
     * 
     * @param object The object
     * @param member The member
     * @return The getter for the specified member of this Object
     * @throws NoGetterException if no getter can be found
     */
    public static Method getGetter(Object object, String member)
            throws NoGetterException {

        String name = member.substring(0, 1).toUpperCase()
                + member.substring(1);

        Method met = null;

        try {
            met = object.getClass().getMethod("get" + name, (Class[]) null);
        } catch (Exception e) {
            try {
                met = object.getClass().getMethod("is" + name,
                        (Class[]) null);
            } catch (Exception ex) {
                throw new NoGetterException(
                        "Could not find a getter for member: " + member
                                + " of object of type "
                                + object.getClass().getSimpleName());
            }
        }

        return met;

    }
}

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