1 /*
   2  * Copyright (c) 2010, 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 java.lang;
  27 
  28 import java.lang.annotation.*;
  29 
  30 /**
  31  * A programmer assertion that the body of the annotated method or
  32  * constructor does not perform potentially unsafe operations on its
  33  * varargs parameter.  Applying this annotation to a method or
  34  * constructor suppresses unchecked warnings about a
  35  * <i>non-reifiable</i> variable-arity (vararg) type and suppresses
  36  * unchecked warnings about parameterized array creation at call
  37  * sites.
  38  *
  39  * <p> In addition to the usage restrictions imposed by its {@link
  40  * Target @Target} meta-annotation, compilers are required to implement
  41  * additional usage restrictions on this annotation type; it is a
  42  * compile-time error if a method or constructor declaration is
  43  * annotated with a {@code @SafeVarargs} annotation, and either:
  44 
  45  * <ul>
  46  * <li>  the declaration is a fixed-arity method or constructor
  47  *
  48  * <li> the declaration is a variable-arity method that is neither
  49  * {@code static} nor {@code final}.
  50  *
  51  * </ul>
  52  *
  53  * <p> Compilers are encouraged to issue warnings when this annotation
  54  * type is applied to a method or constructor declaration where:
  55  *
  56  * <ul>
  57  *
  58  * <li> The variable-arity parameter has a reifiable element type,
  59  * which includes primitive types, {@code Object}, and {@code String}.
  60  * (The unchecked warnings this annotation type suppresses already do
  61  * not occur for a reifiable element type.)
  62  *
  63  * <li> The body of the method or constructor declaration performs
  64  * potentially unsafe operations, such as an assignment to an element
  65  * of the variable-arity parameter's array that generates an unchecked
  66  * warning.
  67  *
  68  * <p>Future versions of the platform may mandate compiler errors for
  69  * such unsafe operations.
  70  *
  71  * </ul>
  72  *
  73  * @jls3 4.7 Reifiable Types
  74  * @jls3 8.4.1 Formal Parameters
  75  */
  76 @Documented
  77 @Retention(RetentionPolicy.RUNTIME)
  78 @Target({ElementType.CONSTRUCTOR, ElementType.METHOD})
  79 public @interface SafeVarargs {}