1 /*
   2  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.istack.internal;
  27 
  28 import java.lang.annotation.Documented;
  29 import java.lang.annotation.Retention;
  30 import java.lang.annotation.RetentionPolicy;
  31 import java.lang.annotation.Target;
  32 import java.lang.annotation.ElementType;
  33 
  34 /**
  35  * Designates that a field, return value, argument, or a variable is supposed
  36  * to be an {@link String#intern() interned} string.
  37  *
  38  * <p>
  39  * In many places in the istack, we assume Strings to be interned for
  40  * the performance reason. Similarly, In many other places, we don't
  41  * make such an assumption for the performance reason (because intern
  42  * isn't free.)
  43  *
  44  * <p>
  45  * Therefore, distinguishing which part is supposed to be interned and
  46  * which part is supposed to be not is important. This annotation
  47  * allows us to capture that in the code.
  48  *
  49  * @author Kohsuke Kawaguchi
  50  */
  51 @Documented
  52 @Retention(RetentionPolicy.CLASS)
  53 @Target({ElementType.FIELD,ElementType.METHOD,ElementType.PARAMETER,ElementType.LOCAL_VARIABLE})
  54 public @interface Interned {
  55 }