/*
* Copyright 2001-2004 The Apache Software Foundation
*
* 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.apache.commons.collections.functors;
import java.io.Serializable;
import org.apache.commons.collections.Factory;
/**
* Factory implementation that returns the same constant each time.
* <p>
* No check is made that the object is immutable. In general, only immutable
* objects should use the constant factory. Mutable objects should
* use the prototype factory.
*
* @since Commons Collections 3.0
* @version $Revision: 348444 $ $Date: 2005-11-23 14:06:56 +0000 (Wed, 23 Nov 2005) $
*
* @author Stephen Colebourne
*/
public class ConstantFactory implements Factory, Serializable {
/** Serial version UID */
private static final long serialVersionUID = -3520677225766901240L;
/** Returns null each time */
public static final Factory NULL_INSTANCE = new ConstantFactory(null);
/** The closures to call in turn */
private final Object iConstant;
/**
* Factory method that performs validation.
*
* @param constantToReturn the constant object to return each time in the factory
* @return the <code>constant</code> factory.
*/
public static Factory getInstance(Object constantToReturn) {
if (constantToReturn == null) {
return NULL_INSTANCE;
}
return new ConstantFactory(constantToReturn);
}
/**
* Constructor that performs no validation.
* Use <code>getInstance</code> if you want that.
*
* @param constantToReturn the constant to return each time
*/
public ConstantFactory(Object constantToReturn) {
super();
iConstant = constantToReturn;
}
/**
* Always return constant.
*
* @return the stored constant value
*/
public Object create() {
return iConstant;
}
/**
* Gets the constant.
*
* @return the constant
* @since Commons Collections 3.1
*/
public Object getConstant() {
return iConstant;
}
}