diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/java.base/share/classes/java/lang/SafeVarargs.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/java.base/share/classes/java/lang/SafeVarargs.java Tue Sep 12 19:03:39 2017 +0200 @@ -0,0 +1,93 @@ +/* + * Copyright (c) 2010, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +package java.lang; + +import java.lang.annotation.*; + +/** + * A programmer assertion that the body of the annotated method or + * constructor does not perform potentially unsafe operations on its + * varargs parameter. Applying this annotation to a method or + * constructor suppresses unchecked warnings about a + * non-reifiable variable arity (vararg) type and suppresses + * unchecked warnings about parameterized array creation at call + * sites. + * + *
In addition to the usage restrictions imposed by its {@link + * Target @Target} meta-annotation, compilers are required to implement + * additional usage restrictions on this annotation type; it is a + * compile-time error if a method or constructor declaration is + * annotated with a {@code @SafeVarargs} annotation, and either: + *
Compilers are encouraged to issue warnings when this annotation + * type is applied to a method or constructor declaration where: + * + *
+ * + * leads to a {@code ClassCastException} at runtime. + * + *+ * @SafeVarargs // Not actually safe! + * static void m(List<String>... stringLists) { + * Object[] array = stringLists; + * List<Integer> tmpList = Arrays.asList(42); + * array[0] = tmpList; // Semantically invalid, but compiles without warnings + * String s = stringLists[0].get(0); // Oh no, ClassCastException at runtime! + * } + *
Future versions of the platform may mandate compiler errors for + * such unsafe operations. + * + *