core/src/main/java/org/apache/commons/proxy2/invoker/NullInvoker.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.proxy2.invoker;

import java.io.Serializable;
import java.lang.reflect.Method;

import org.apache.commons.proxy2.Invoker;
import org.apache.commons.proxy2.ProxyUtils;

/**
 * An {@link Invoker} implementation which merely returns null for all method invocations. This class is useful for
 * scenarios where the "null object" design pattern is needed.
 * 
 * @author James Carman
 * @since 1.0
 */
public class NullInvoker implements Invoker, Serializable
{
    /** Serialization version */
    private static final long serialVersionUID = 1L;

    /**
     * Statically available instance.
     */
    public static final NullInvoker INSTANCE = new NullInvoker();

    //******************************************************************************************************************
    // Invoker Implementation
    //******************************************************************************************************************

    /**
     * {@inheritDoc}
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
    {
        final Class<?> returnType = method.getReturnType();
        return ProxyUtils.nullValue(returnType);
    }
}