Java Method Call invokeInstanceMethod(Object target, String methodName, Class type, Object arg)

Description

Invoke method.

License

Open Source License

Parameter

Parameter	Description
target	the target
methodName	the method name
type	the type
arg	the arg

Return

method's return value

Declaration

public static Object invokeInstanceMethod(Object target, String methodName, Class<?> type, Object arg) 

Method Source Code

//package com.java2s;
/*/*from w  w w .  j  av  a2s.c  o m*/
 * JBoss, Home of Professional Open Source.
 * Copyright 2011, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

import java.lang.reflect.Method;

public class Main {
    private static final Class[] EMPTY_CLASSES = new Class[0];
    private static final Object[] EMPTY_ARGS = new Object[0];

    /**
     * Invoke no-param method.
     *
     * @param target     the object on which to invoke method
     * @param methodName the name of the method
     * @return value returned by invoked method
     */
    public static Object invokeInstanceMethod(Object target, String methodName) {
        return invokeInstanceMethod(target, methodName, EMPTY_CLASSES, EMPTY_ARGS);
    }

    /**
     * Invoke method.
     *
     * @param target     the target
     * @param methodName the method name
     * @param type       the type
     * @param arg        the arg
     * @return method's return value
     */
    public static Object invokeInstanceMethod(Object target, String methodName, Class<?> type, Object arg) {
        return invokeInstanceMethod(target, methodName, new Class[] { type }, new Object[] { arg });
    }

    /**
     * Invoke method.
     *
     * @param target     the target
     * @param methodName the method name
     * @param types      the types
     * @param args       the args
     * @return method's return value
     */
    public static Object invokeInstanceMethod(Object target, String methodName, Class[] types, Object[] args) {
        if (target == null)
            throw new IllegalArgumentException("Null target");

        return invokeMethod(target, target.getClass(), methodName, types, args);
    }

    /**
     * Invoke method.
     *
     * @param target     the target
     * @param clazz      the class
     * @param methodName the method name
     * @param types      the types
     * @param args       the args
     * @return method's return value
     */
    private static Object invokeMethod(Object target, Class<?> clazz, String methodName, Class[] types,
            Object[] args) {
        final Method m = findMethod(clazz, methodName, types);
        try {
            return m.invoke(target, args);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Find method.
     *
     * @param clazz      the class
     * @param methodName the method name
     * @param types      the types
     * @return method's return value
     */
    private static Method findMethod(Class<?> clazz, String methodName, Class[] types) {
        if (clazz == null)
            throw new IllegalArgumentException("Null class");
        if (methodName == null)
            throw new IllegalArgumentException("Null method name");

        try {
            Class<?> current = clazz;
            while (current != null) {
                try {
                    final Method m = current.getDeclaredMethod(methodName, types);
                    m.setAccessible(true);
                    return m;
                } catch (NoSuchMethodException ignored) {
                }
                current = current.getSuperclass();
            }
        } catch (Throwable t) {
            throw new RuntimeException(t);
        }
        throw new IllegalStateException("Couldn't find method: " + clazz.getName() + " / " + methodName);
    }
}

Related

1. invokeGenericMethodOneArg(final Object obj, final String methodName, final Object arg)
2. invokeGet(Object o, String fieldName)
3. invokeGetClasspathMethodIfItExists(ClassLoader cl)
4. invokeGetMethodWithSameName(Object object, Method method)
5. invokeHeritedMethod(Object target, String method, Class klass)
6. invokeIteratorCallable(String callableClassName, ClassLoader cl)
7. invokeMXMethod(String methodName)
8. invokeNoArgs(Object instance, Method method, Class returnType)
9. invokeNoArgsMethod(Object object, String methodName)