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| <title>Chapter 6. Varargs</title><link rel="stylesheet" href="aspectj-docs.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.44"><link rel="home" href="index.html" title="The AspectJTM 5 Development Kit Developer's Notebook"><link rel="up" href="index.html" title="The AspectJTM 5 Development Kit Developer's Notebook"><link rel="previous" href="covariance-and-join-point-matching.html" title="Covariant methods and Join Point matching"><link rel="next" href="varargs-in-pcds.html" title="Using Variable-length arguments in advice and pointcut expressions"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 6. Varargs</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="covariance-and-join-point-matching.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="varargs-in-pcds.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><h2 class="title"><a name="varargs"></a>Chapter 6. Varargs</h2></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="varargs.html#varargs-inJava5">Variable-length Argument Lists in Java 5</a></dt><dd><dl><dt><a href="varargs.html#calling-methods-and-constructors-with-variable-length-arguments">Calling Methods and Constructors with variable-length arguments</a></dt></dl></dd><dt><a href="varargs-in-pcds.html">Using Variable-length arguments in advice and pointcut expressions</a></dt><dd><dl><dt><a href="varargs-in-pcds.html#matching-signatures-based-on-variable-length-argument-types">Matching signatures based on variable length argument types</a></dt><dt><a href="varargs-in-pcds.html#exposing-variable-length-arguments-as-context-in-pointcuts-and-advice">Exposing variable-length arguments as context in pointcuts and advice</a></dt></dl></dd></dl></div><div class="sect1"><a name="varargs-inJava5"></a><div class="titlepage"><div><h2 class="title" style="clear: both"><a name="varargs-inJava5"></a>Variable-length Argument Lists in Java 5</h2></div></div><p> | |
| Java 5 (and hence AspectJ 5) allows you to specify methods that take a | |
| variable number of arguments of a specified type. This is achieved using | |
| an ellipsis (...) in the method signature as shown: | |
| </p><pre class="programlisting"> | |
| public void foo(int i, String... strings) { | |
| } | |
| </pre><p> | |
| A method or constructor may take at most one variable length argument, and | |
| this must always be the last declared argument in the signature. | |
| </p><div class="sect2"><a name="calling-methods-and-constructors-with-variable-length-arguments"></a><div class="titlepage"><div><h3 class="title"><a name="calling-methods-and-constructors-with-variable-length-arguments"></a>Calling Methods and Constructors with variable-length arguments</h3></div></div><p> | |
| A <span class="emphasis"><i>varargs</i></span> method may be called with zero or more arguments | |
| in the variable argument position. For example, given the definition of | |
| <tt>foo</tt> above, the following calls are all legal: | |
| </p><pre class="programlisting"> | |
| foo(5); | |
| foo(5,"One String"); | |
| foo(7,"One String","Two Strings"); | |
| foo(3,"One String","Two Strings","Three Strings"); | |
| </pre><p>A <span class="emphasis"><i>varargs</i></span> parameter is treated as an array within the | |
| defining member. So in the body of <tt>foo</tt> we could write for example: | |
| </p><pre class="programlisting"> | |
| public void foo(int i, String... strings) { | |
| String[] someStrings = strings; | |
| // rest of method body | |
| } | |
| </pre><p>One consequence of this treatment of a varargs parameter as an array | |
| is that you can also call a varargs method with an array:</p><pre class="programlisting"> | |
| foo(7,new String[] {"One String","Two Strings"}); | |
| </pre></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="covariance-and-join-point-matching.html">Prev</a> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right"> <a accesskey="n" href="varargs-in-pcds.html">Next</a></td></tr><tr><td width="40%" align="left">Covariant methods and Join Point matching </td><td width="20%" align="center"><a accesskey="u" href="index.html">Up</a></td><td width="40%" align="right"> Using Variable-length arguments in advice and pointcut expressions</td></tr></table></div></body></html> |