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94 lines
2.7 KiB
94 lines
2.7 KiB
/*
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* Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.lang;
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import java.lang.annotation.*;
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/**
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* A programmer assertion that the body of the annotated method or
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* constructor does not perform potentially unsafe operations on its
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* varargs parameter. Applying this annotation to a method or
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* constructor suppresses unchecked warnings about a
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* <i>non-reifiable</i> variable arity (vararg) type and suppresses
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* unchecked warnings about parameterized array creation at call
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* sites.
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*
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* <p> In addition to the usage restrictions imposed by its {@link
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* Target @Target} meta-annotation, compilers are required to implement
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* additional usage restrictions on this annotation type; it is a
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* compile-time error if a method or constructor declaration is
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* annotated with a {@code @SafeVarargs} annotation, and either:
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* <ul>
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* <li> the declaration is a fixed arity method or constructor
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*
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* <li> the declaration is a variable arity method that is neither
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* {@code static} nor {@code final}.
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*
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* </ul>
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*
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* <p> Compilers are encouraged to issue warnings when this annotation
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* type is applied to a method or constructor declaration where:
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*
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* <ul>
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*
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* <li> The variable arity parameter has a reifiable element type,
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* which includes primitive types, {@code Object}, and {@code String}.
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* (The unchecked warnings this annotation type suppresses already do
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* not occur for a reifiable element type.)
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*
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* <li> The body of the method or constructor declaration performs
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* potentially unsafe operations, such as an assignment to an element
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* of the variable arity parameter's array that generates an unchecked
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* warning. Some unsafe operations do not trigger an unchecked
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* warning. For example, the aliasing in
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*
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* <blockquote><pre>
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* @SafeVarargs // Not actually safe!
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* static void m(List<String>... stringLists) {
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* Object[] array = stringLists;
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* List<Integer> tmpList = Arrays.asList(42);
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* array[0] = tmpList; // Semantically invalid, but compiles without warnings
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* String s = stringLists[0].get(0); // Oh no, ClassCastException at runtime!
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* }
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* </pre></blockquote>
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*
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* leads to a {@code ClassCastException} at runtime.
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*
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* <p>Future versions of the platform may mandate compiler errors for
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* such unsafe operations.
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*
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* </ul>
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*
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* @since 1.7
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* @jls 4.7 Reifiable Types
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* @jls 8.4.1 Formal Parameters
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* @jls 9.6.3.7 @SafeVarargs
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*/
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@Documented
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@Retention(RetentionPolicy.RUNTIME)
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@Target({ElementType.CONSTRUCTOR, ElementType.METHOD})
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public @interface SafeVarargs {}
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