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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.math.ode.sampling;
19  
20  
21  /**
22   * This class is a step handler that does nothing.
23  
24   * <p>This class is provided as a convenience for users who are only
25   * interested in the final state of an integration and not in the
26   * intermediate steps. Its handleStep method does nothing.</p>
27   *
28   * <p>Since this class has no internal state, it is implemented using
29   * the Singleton design pattern. This means that only one instance is
30   * ever created, which can be retrieved using the getInstance
31   * method. This explains why there is no public constructor.</p>
32   *
33   * @see StepHandler
34   * @version $Revision: 786881 $ $Date: 2009-06-20 14:53:08 -0400 (Sat, 20 Jun 2009) $
35   * @since 1.2
36   */
37  
38  public class DummyStepHandler implements StepHandler {
39  
40    /** Private constructor.
41     * The constructor is private to prevent users from creating
42     * instances (Singleton design-pattern).
43     */
44    private DummyStepHandler() {
45    }
46  
47    /** Get the only instance.
48     * @return the only instance
49     */
50    public static DummyStepHandler getInstance() {
51      return instance;
52    }
53  
54    /** Determines whether this handler needs dense output.
55     * Since this handler does nothing, it does not require dense output.
56     * @return always false
57     */
58    public boolean requiresDenseOutput() {
59      return false;
60    }
61  
62    /** Reset the step handler.
63     * Initialize the internal data as required before the first step is
64     * handled.
65     */
66    public void reset() {
67    }
68  
69    /**
70     * Handle the last accepted step.
71     * This method does nothing in this class.
72     * @param interpolator interpolator for the last accepted step. For
73     * efficiency purposes, the various integrators reuse the same
74     * object on each call, so if the instance wants to keep it across
75     * all calls (for example to provide at the end of the integration a
76     * continuous model valid throughout the integration range), it
77     * should build a local copy using the clone method and store this
78     * copy.
79     * @param isLast true if the step is the last one
80     */
81    public void handleStep(final StepInterpolator interpolator, final boolean isLast) {
82    }
83  
84    /** The only instance. */
85    private static final DummyStepHandler instance = new DummyStepHandler();
86  
87  }