| /* |
| * 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; |
| |
| /** |
| * <p> |
| * A very simple implementation of the {@link ConcurrentInitializer} interface |
| * which always returns the same object. |
| * </p> |
| * <p> |
| * 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. |
| * </p> |
| * <p> |
| * 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}. |
| * </p> |
| * |
| * @since 3.0 |
| * @param <T> the type of the object managed by this initializer |
| */ |
| public class ConstantInitializer<T> implements ConcurrentInitializer<T> { |
| /** 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 <b>null</b>, then {@code get()} will return |
| * <b>null</b>, 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 |
| * <b>true</b> 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())); |
| } |
| } |