001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.math.ode.sampling;
019    
020    
021    /**
022     * This class is a step handler that does nothing.
023    
024     * <p>This class is provided as a convenience for users who are only
025     * interested in the final state of an integration and not in the
026     * intermediate steps. Its handleStep method does nothing.</p>
027     *
028     * <p>Since this class has no internal state, it is implemented using
029     * the Singleton design pattern. This means that only one instance is
030     * ever created, which can be retrieved using the getInstance
031     * method. This explains why there is no public constructor.</p>
032     *
033     * @see StepHandler
034     * @version $Revision: 786881 $ $Date: 2009-06-20 14:53:08 -0400 (Sat, 20 Jun 2009) $
035     * @since 1.2
036     */
037    
038    public class DummyStepHandler implements StepHandler {
039    
040      /** Private constructor.
041       * The constructor is private to prevent users from creating
042       * instances (Singleton design-pattern).
043       */
044      private DummyStepHandler() {
045      }
046    
047      /** Get the only instance.
048       * @return the only instance
049       */
050      public static DummyStepHandler getInstance() {
051        return instance;
052      }
053    
054      /** Determines whether this handler needs dense output.
055       * Since this handler does nothing, it does not require dense output.
056       * @return always false
057       */
058      public boolean requiresDenseOutput() {
059        return false;
060      }
061    
062      /** Reset the step handler.
063       * Initialize the internal data as required before the first step is
064       * handled.
065       */
066      public void reset() {
067      }
068    
069      /**
070       * Handle the last accepted step.
071       * This method does nothing in this class.
072       * @param interpolator interpolator for the last accepted step. For
073       * efficiency purposes, the various integrators reuse the same
074       * object on each call, so if the instance wants to keep it across
075       * all calls (for example to provide at the end of the integration a
076       * continuous model valid throughout the integration range), it
077       * should build a local copy using the clone method and store this
078       * copy.
079       * @param isLast true if the step is the last one
080       */
081      public void handleStep(final StepInterpolator interpolator, final boolean isLast) {
082      }
083    
084      /** The only instance. */
085      private static final DummyStepHandler instance = new DummyStepHandler();
086    
087    }