invoke Method on object using reflection - Java Reflection

Java examples for Reflection:Method

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Description

invoke Method on object using reflection

Demo Code

/*//  ww  w  .  j a v a2 s .  c  o m
 *  PHEX - The pure-java Gnutella-servent.
 *  Copyright (C) 2001 - 2005 Phex Development Group
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
import java.lang.reflect.*;

public class Main{

    public static Object invokeMethod(Object obj, String methodName,
            Object param) throws Throwable {
        Object[] params = { param };
        return invokeMethod(obj, methodName, params);
    }
    public static Object invokeMethod(Object obj, String methodName,
            Object[] params) throws Throwable {
        Class[] paramTypes = null;
        if (params != null) {
            paramTypes = new Class[params.length];
            for (int i = 0; i < params.length; i++) {
                paramTypes[i] = params[i].getClass();
            }
        }
        return invokeMethod(obj, methodName, params, paramTypes);
    }
    public static Object invokeMethod(Object obj, String methodName,
            Object[] params, Class[] paramTypes) throws Throwable {
        Class clazz;
        if (obj instanceof Class) {
            clazz = (Class) obj;
        } else {
            clazz = obj.getClass();
        }

        try {
            Method method = clazz.getDeclaredMethod(methodName, paramTypes);
            method.setAccessible(true);
            Object retVal = method.invoke(obj, params);
            return retVal;
        } catch (IllegalAccessException exp) {
            exp.printStackTrace();
            throw new RuntimeException(exp.getMessage());
        } catch (InvocationTargetException exp) {
            throw exp.getTargetException();
        } catch (NoSuchMethodException exp) {
            exp.printStackTrace();
            throw new RuntimeException(exp.getMessage());
        }
    }
}

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