1 package javax.annotation.concurrent; 2 3 import java.lang.annotation.Documented; 4 import java.lang.annotation.ElementType; 5 import java.lang.annotation.Retention; 6 import java.lang.annotation.RetentionPolicy; 7 import java.lang.annotation.Target; 8 9 /* 10 * Copyright (c) 2005 Brian Goetz 11 * Released under the Creative Commons Attribution License 12 * (http://creativecommons.org/licenses/by/2.5) 13 * Official home: http://www.jcip.net 14 */ 15 16 /** 17 * Immutable 18 * 19 * The class to which this annotation is applied is immutable. This means that 20 * its state cannot be seen to change by callers. Of necessity this means that 21 * all public fields are final, and that all public final reference fields refer 22 * to other immutable objects, and that methods do not publish references to any 23 * internal state which is mutable by implementation even if not by design. 24 * Immutable objects may still have internal mutable state for purposes of 25 * performance optimization; some state variables may be lazily computed, so 26 * long as they are computed from immutable state and that callers cannot tell 27 * the difference. 28 * 29 * Immutable objects are inherently thread-safe; they may be passed between 30 * threads or published without synchronization. 31 */ 32 @Documented 33 @Target(ElementType.TYPE) 34 @Retention(RetentionPolicy.CLASS) 35 public @interface Immutable { 36 } 37
