- /*
- * 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.Transformer;
-
- /**
- * Transformer 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: 1.5 $ $Date: 2004/05/16 11:36:31 $
- *
- * @author Stephen Colebourne
- */
- public class ConstantTransformer implements Transformer, Serializable {
-
- /** Serial version UID */
- static final long serialVersionUID = 6374440726369055124L;
-
- /** Returns null each time */
- public static final Transformer NULL_INSTANCE = new ConstantTransformer(null);
-
- /** The closures to call in turn */
- private final Object iConstant;
-
- /**
- * Transformer method that performs validation.
- *
- * @param constantToReturn the constant object to return each time in the factory
- * @return the <code>constant</code> factory.
- */
- public static Transformer getInstance(Object constantToReturn) {
- if (constantToReturn == null) {
- return NULL_INSTANCE;
- }
- return new ConstantTransformer(constantToReturn);
- }
-
- /**
- * Constructor that performs no validation.
- * Use <code>getInstance</code> if you want that.
- *
- * @param constantToReturn the constant to return each time
- */
- public ConstantTransformer(Object constantToReturn) {
- super();
- iConstant = constantToReturn;
- }
-
- /**
- * Transforms the input by ignoring it and returning the stored constant instead.
- *
- * @param input the input object which is ignored
- * @return the stored constant
- */
- public Object transform(Object input) {
- return iConstant;
- }
-
- /**
- * Gets the constant.
- *
- * @return the constant
- * @since Commons Collections 3.1
- */
- public Object getConstant() {
- return iConstant;
- }
-
- }