Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl;

import java.lang.reflect.Method;

import org.apache.commons.lang3.StringUtils;

/**

 *

 * @author jjdelcerro

 */

public class InstanceUtils {

    public static Object callmethod(Object instance, String methodName, Object args[]) throws Exception {

        if( StringUtils.isBlank(methodName) ) {

            throw new NullPointerException("A method name was expected to invoke and a null was received");

        }

        if( instance==null ) {

            throw new NullPointerException("An object pointer was expected to invoke method "+methodName+" and a null was received");

        }

        Class[] parameterTypes = new Class[args.length];

        Object[] parameters = new Object[args.length];

        for (int i = 0; i < parameters.length; i++) {

            Object parameter = args[i];

            parameters[i] = parameter;

            if( parameter==null ) {

                parameterTypes[i] = null;

            } else {

                parameterTypes[i] = parameter.getClass();

            }

        }

        Class<?> theClass = instance.getClass();

        Method method;

        try {

            method = theClass.getMethod(methodName, parameterTypes);

        } catch(NoSuchMethodException ex) {

            // Esto es para esquivar casos como tener un ArrayList de objects y 

            // hacer algo como  arr.add(10). Dice que no hay ningun metodo add

            // que reciba un Integer, por que realmente el add esta declarado como

            // que recibe un object.

            // Ver TestInterpreter metodo testListAppend.

            for (Method m : theClass.getMethods()) {

                if( StringUtils.equals(m.getName(), methodName) && parameterTypes.length == m.getParameterTypes().length) {

                    parameterTypes = m.getParameterTypes();

                    break;

                }

            }

            method = theClass.getMethod(methodName, parameterTypes);

        }

        Object value = method.invoke(instance, parameters);

        return value;

    }

}