/*
* Copyright (c) 2009-2010 Lockheed Martin Corporation
*
* Licensed 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.eurekastreams.commons.reflection;
import java.lang.reflect.Constructor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Class to aid in object instantiation via reflection.
*/
public class ReflectiveInstantiator
{
/**
* Logger.
*/
private Log log = LogFactory.getLog(ReflectiveInstantiator.class);
/**
* Instantiate an object of the input class type with the empty constructor.
* Private constructors are handled.
*
* @param objType
* the type of class to instantiate.
*
* @return an object of the input class type.
*/
public Object instantiateObject(final Class< ? > objType)
{
Constructor< ? > emptyConstructor = null;
for (Constructor< ? > constructor : objType.getDeclaredConstructors())
{
if (constructor.getParameterTypes().length == 0)
{
emptyConstructor = constructor;
break;
}
}
if (emptyConstructor == null)
{
String message = "Cannot find empty constructor for " + objType.getName();
log.error(message);
throw new RuntimeException(message);
}
// set it accessible, just in case
emptyConstructor.setAccessible(true);
Object obj = null;
try
{
obj = emptyConstructor.newInstance(new Object[0]);
}
catch (Exception e)
{
String message = "Couldn't instantiate: " + objType.getName();
log.error(message, e);
throw new RuntimeException(message);
}
return obj;
}
}