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Statistical sampling library for use in virtdata libraries, based on apache commons math 4

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/*
 * 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.lang3.concurrent;

import java.util.Objects;

/**
 * 

* A very simple implementation of the {@link ConcurrentInitializer} interface * which always returns the same object. *

*

* An instance of this class is passed a reference to an object when it is * constructed. The {@link #get()} method just returns this object. No * synchronization is required. *

*

* This class is useful for instance for unit testing or in cases where a * specific object has to be passed to an object which expects a * {@link ConcurrentInitializer}. *

* * @since 3.0 * @param the type of the object managed by this initializer */ public class ConstantInitializer implements ConcurrentInitializer { /** Constant for the format of the string representation. */ private static final String FMT_TO_STRING = "ConstantInitializer@%d [ object = %s ]"; /** Stores the managed object. */ private final T object; /** * Creates a new instance of {@code ConstantInitializer} and initializes it * with the object to be managed. The {@code get()} method will always * return the object passed here. This class does not place any restrictions * on the object. It may be null, then {@code get()} will return * null, too. * * @param obj the object to be managed by this initializer */ public ConstantInitializer(final T obj) { object = obj; } /** * Directly returns the object that was passed to the constructor. This is * the same object as returned by {@code get()}. However, this method does * not declare that it throws an exception. * * @return the object managed by this initializer */ public final T getObject() { return object; } /** * Returns the object managed by this initializer. This implementation just * returns the object passed to the constructor. * * @return the object managed by this initializer * @throws ConcurrentException if an error occurs */ @Override public T get() throws ConcurrentException { return getObject(); } /** * Returns a hash code for this object. This implementation returns the hash * code of the managed object. * * @return a hash code for this object */ @Override public int hashCode() { return getObject() != null ? getObject().hashCode() : 0; } /** * Compares this object with another one. This implementation returns * true if and only if the passed in object is an instance of * {@code ConstantInitializer} which refers to an object equals to the * object managed by this instance. * * @param obj the object to compare to * @return a flag whether the objects are equal */ @Override public boolean equals(final Object obj) { if (this == obj) { return true; } if (!(obj instanceof ConstantInitializer)) { return false; } final ConstantInitializer c = (ConstantInitializer) obj; return Objects.equals(getObject(), c.getObject()); } /** * Returns a string representation for this object. This string also * contains a string representation of the object managed by this * initializer. * * @return a string for this object */ @Override public String toString() { return String.format(FMT_TO_STRING, Integer.valueOf(System.identityHashCode(this)), String.valueOf(getObject())); } }




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