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The Apache Commons Math project is a library of lightweight, self-contained mathematics and statistics components addressing the most common practical problems not immediately available in the Java programming language or commons-lang.
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.math3.ode.sampling;
/**
* This class is a step handler that does nothing.
* This class is provided as a convenience for users who are only
* interested in the final state of an integration and not in the
* intermediate steps. Its handleStep method does nothing.
*
* Since this class has no internal state, it is implemented using
* the Singleton design pattern. This means that only one instance is
* ever created, which can be retrieved using the getInstance
* method. This explains why there is no public constructor.
*
* @see StepHandler
* @since 1.2
*/
public class DummyStepHandler implements StepHandler {
/** Private constructor.
* The constructor is private to prevent users from creating
* instances (Singleton design-pattern).
*/
private DummyStepHandler() {
}
/** Get the only instance.
* @return the only instance
*/
public static DummyStepHandler getInstance() {
return LazyHolder.INSTANCE;
}
/** {@inheritDoc} */
public void init(double t0, double[] y0, double t) {
}
/**
* Handle the last accepted step.
* This method does nothing in this class.
* @param interpolator interpolator for the last accepted step. For
* efficiency purposes, the various integrators reuse the same
* object on each call, so if the instance wants to keep it across
* all calls (for example to provide at the end of the integration a
* continuous model valid throughout the integration range), it
* should build a local copy using the clone method and store this
* copy.
* @param isLast true if the step is the last one
*/
public void handleStep(final StepInterpolator interpolator, final boolean isLast) {
}
// CHECKSTYLE: stop HideUtilityClassConstructor
/** Holder for the instance.
* We use here the Initialization On Demand Holder Idiom.
*/
private static class LazyHolder {
/** Cached field instance. */
private static final DummyStepHandler INSTANCE = new DummyStepHandler();
}
// CHECKSTYLE: resume HideUtilityClassConstructor
/** Handle deserialization of the singleton.
* @return the singleton instance
*/
private Object readResolve() {
// return the singleton instance
return LazyHolder.INSTANCE;
}
}