MinSelector.java
/* Copyright 2013-2022 CS GROUP
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS 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.orekit.rugged.utils;
/** Selector for min value.
* <p>
* This selector considers {@code Double.NaN} values correspond
* to non-initialized data that should be ignored rather than
* selected.
* </p>
* @see MaxSelector
* @author Luc Maisonobe
*/
public class MinSelector extends Selector {
/** Private constructor for singleton.
*/
private MinSelector() {
}
/** Get the unique instance.
* @return unique instance of the min selector.
*/
public static MinSelector getInstance() {
return LazyHolder.INSTANCE;
}
/** Check if first value should be selected.
* @param v1 first value
* @param v2 second value
* @return true if v1 is lower than v2, or if v2 is {@code Double.NaN}
*/
@Override
public boolean selectFirst(final double v1, final double v2) {
return v1 < v2 || Double.isNaN(v2);
}
/** Holder for the min selector singleton.
* <p>
* We use the Initialization On Demand Holder Idiom to store
* the singletons, as it is both thread-safe, efficient (no
* synchronization) and works with all versions of java.
* </p>
*/
private static class LazyHolder {
/** Unique instance. */
private static final MinSelector INSTANCE = new MinSelector();
/** Private constructor.
* <p>This class is a utility class, it should neither have a public
* nor a default constructor. This private constructor prevents
* the compiler from generating one automatically.</p>
*/
private LazyHolder() {
}
}
}