Java Reflection Method Name getMethod(final Class clazz, final String methodName, final boolean factoryMethod, final boolean failIfNotFound)

Description

get Method

License

Open Source License

Declaration

private static Method getMethod(final Class<?> clazz, final String methodName, final boolean factoryMethod,
            final boolean failIfNotFound) 

Method Source Code

//package com.java2s;
/*//from  ww w  .j a v a  2  s  . c o  m
 * Copyright (c) 2013, FOSS Nova Software foundation (FNSF),
 * and individual contributors as indicated by the @author tags.
 *
 * 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;
import java.lang.reflect.Modifier;

public class Main {
    private static final Class<?>[] emptyClassArray = new Class[0];

    private static Method getMethod(final Class<?> clazz, final String methodName, final boolean factoryMethod,
            final boolean failIfNotFound) {
        if (methodName == null)
            return null;
        final Method method = findMethod(clazz, methodName, failIfNotFound);
        if (method == null && !failIfNotFound)
            return null;
        final int methodModifiers = method.getModifiers();
        if (Modifier.isAbstract(methodModifiers))
            throw new UnsupportedOperationException("Method '" + methodName + "' cannot be abstract");
        if (Modifier.isStatic(methodModifiers) && !factoryMethod)
            throw new UnsupportedOperationException("Factory method '" + methodName + "' have to be static");
        final Class<?> returnType = method.getReturnType();
        if (factoryMethod) {
            if (returnType.equals(Void.class) || returnType.equals(Void.TYPE)) {
                throw new UnsupportedOperationException("Factory method '" + methodName + "' cannot return void");
            }
        } else {
            if (!returnType.equals(Void.class) && !returnType.equals(Void.TYPE)) {
                throw new UnsupportedOperationException("Method '" + methodName + "' have to return void");
            }
        }
        if (method.getParameterTypes().length > 0) {
            throw new UnsupportedOperationException("Method '" + methodName + "' have to have no parameters");
        }
        assertNotThrowingCheckedExceptions(method);
        return method;
    }

    static Method getMethod(final Class<?> clazz, final String methodName, final boolean failIfNotFound) {
        return getMethod(clazz, methodName, false, failIfNotFound);
    }

    private static Method findMethod(final Class<?> clazz, final String methodName, final boolean failIfNotFound) {
        try {
            return clazz.getMethod(methodName, emptyClassArray);
        } catch (final NoSuchMethodException e) {
            if (failIfNotFound) {
                throw new UnsupportedOperationException("Method '" + methodName + "' without parameters not found",
                        e);
            }
        }
        return null;
    }

    private static void assertNotThrowingCheckedExceptions(final Method method) {
        final Class<?>[] exceptions = method.getExceptionTypes();
        for (final Class<?> exception : exceptions) {
            if (Exception.class.isAssignableFrom(exception)) {
                throw new UnsupportedOperationException("Method '" + method.getName()
                        + "' cannot throw checked exception '" + exception.getSimpleName() + "'");
            }
        }
    }
}

Related

1. getMethod(Class c, String name, Class... argTypes)
2. getMethod(Class clazz, String methodName)
3. getMethod(Class clazz, String methodName, Class[] calledTypes)
4. getMethod(Class type, String methodName, Class... params)
5. getMethod(final Class atClass, final String name, final Class[] paramType)
6. getMethod(final String methodName, final Class objClass, final Class[] paramClasses)
7. getMethod(int requireMod, int bannedMod, Class clazz, String methodName, Class... params)
8. getMethod(Method[] methods, String name)
9. getMethod(Method[] methods, String name, Class[] params)