michael@0: /*
michael@0:  * ====================================================================
michael@0:  *
michael@0:  *  Licensed to the Apache Software Foundation (ASF) under one or more
michael@0:  *  contributor license agreements.  See the NOTICE file distributed with
michael@0:  *  this work for additional information regarding copyright ownership.
michael@0:  *  The ASF licenses this file to You under the Apache License, Version 2.0
michael@0:  *  (the "License"); you may not use this file except in compliance with
michael@0:  *  the License.  You may obtain a copy of the License at
michael@0:  *
michael@0:  *      http://www.apache.org/licenses/LICENSE-2.0
michael@0:  *
michael@0:  *  Unless required by applicable law or agreed to in writing, software
michael@0:  *  distributed under the License is distributed on an "AS IS" BASIS,
michael@0:  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
michael@0:  *  See the License for the specific language governing permissions and
michael@0:  *  limitations under the License.
michael@0:  * ====================================================================
michael@0:  *
michael@0:  * This software consists of voluntary contributions made by many
michael@0:  * individuals on behalf of the Apache Software Foundation.  For more
michael@0:  * information on the Apache Software Foundation, please see
michael@0:  * <http://www.apache.org/>.
michael@0:  *
michael@0:  */
michael@0: package ch.boye.httpclientandroidlib.annotation;
michael@0: 
michael@0: import java.lang.annotation.Documented;
michael@0: import java.lang.annotation.ElementType;
michael@0: import java.lang.annotation.Retention;
michael@0: import java.lang.annotation.RetentionPolicy;
michael@0: import java.lang.annotation.Target;
michael@0: 
michael@0: /**
michael@0:  * The class to which this annotation is applied is immutable.  This means that
michael@0:  * its state cannot be seen to change by callers, which implies that
michael@0:  * <ul>
michael@0:  * <li> all public fields are final, </li>
michael@0:  * <li> all public final reference fields refer to other immutable objects, and </li>
michael@0:  * <li> constructors and methods do not publish references to any internal state
michael@0:  *      which is potentially mutable by the implementation. </li>
michael@0:  * </ul>
michael@0:  * Immutable objects may still have internal mutable state for purposes of performance
michael@0:  * optimization; some state variables may be lazily computed, so long as they are computed
michael@0:  * from immutable state and that callers cannot tell the difference.
michael@0:  * <p>
michael@0:  * Immutable objects are inherently thread-safe; they may be passed between threads or
michael@0:  * published without synchronization.
michael@0:  * <p>
michael@0:  * Based on code developed by Brian Goetz and Tim Peierls and concepts
michael@0:  * published in 'Java Concurrency in Practice' by Brian Goetz, Tim Peierls,
michael@0:  * Joshua Bloch, Joseph Bowbeer, David Holmes and Doug Lea.
michael@0:  */
michael@0: @Documented
michael@0: @Target(ElementType.TYPE)
michael@0: @Retention(RetentionPolicy.CLASS) // The original version used RUNTIME
michael@0: public @interface Immutable {
michael@0: }