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diff --git a/website/features/EqualsAndHashCode.html b/website/features/EqualsAndHashCode.html new file mode 100644 index 00000000..3e19814c --- /dev/null +++ b/website/features/EqualsAndHashCode.html @@ -0,0 +1,88 @@ +<!DOCTYPE html> +<html><head> + <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> + <link rel="stylesheet" type="text/css" href="../logi/reset.css" /> + <link rel="stylesheet" type="text/css" href="features.css" /> + <link rel="shortcut icon" href="../favicon.ico" type="image/x-icon" /> + <meta name="description" content="Spice up your java" /> + <title>@Data</title> +</head><body><div id="pepper"> + <div class="minimumHeight"></div> + <div class="meat"> + <div class="header"><a href="../index.html">Project Lombok</a></div> + <h1>@EqualsAndHashCode</h1> + <div class="byline">Equality made easy: Generates <code>hashCode</code> and <code>equals</code> implementations from the fields of your object.</div> + <div class="overview"> + <h3>Overview</h3> + <p> + Any class definition may be annotated with <code>@EqualsAndHashCode</code> to let lombok generate implementations of the + <code>equals(Object other)</code> and <code>hashCode()</code> methods. By default, it'll use all non-static, non-transient + fields, but you can exclude more fields by naming them in the optional <code>exclude</code> parameter to the annotation. + </p><p> + By setting <code>callSuper</code> to <em>true</em>, you can include the <code>equals</code> and <code>hashCode</code> methods of your superclass in the generated methods. + For <code>hashCode</code>, the result of <code>super.hashCode()</code> is included in the hash algorithm, and for <code>equals</code>, the generated method will return + false if the super implementation thinks it is not equal to the passed in object. Be aware that not all <code>equals</code> implementations handle this situation properly. + However, lombok-generated <code>equals</code> implementations <strong>do</strong> handle this situation properly, so you can safely call your superclass equals if it, too, + has a lombok-generated <code>equals</code> method.<br /> + </p><p> + Setting <code>callSuper</code> to <em>true</em> when you don't extend anything (you extend <code>java.lang.Object</code>) is a compile-time error, because it would turn + the generated <code>equals()</code> and <code>hashCode()</code> implementations into having the same behaviour as simply inheriting these methods from <code>java.lang.Object</code>: + only the same object will be equal to each other and will have the same hashCode. Obviously, inheriting <code>java.lang.Object</code> is the right strategy if you want this behaviour. + Not setting <code>callSuper</code> to <em>true</em> when you extend another class generates a warning, because unless the superclass has no (equality-important) fields, lombok + cannot generate an implementation for you that takes into account the fields declared by your superclasses. You'll need to write your own implementations, or rely on the + <code>callSuper</code> chaining facility. + </p> + </div> + <div class="snippets"> + <div class="pre"> + <h3>With Lombok</h3> + <div class="snippet">@HTML_PRE@</div> + </div> + <div class="sep"></div> + <div class="post"> + <h3>Vanilla Java</h3> + <div class="snippet">@HTML_POST@</div> + </div> + </div> + <div style="clear: left;"></div> + <div class="overview"> + <h3>Small print</h3><div class="smallprint"> + <p> + Arrays are 'deep' compared/hashCoded, which means that arrays that contain themselves will result in <code>StackOverflowError</code>s. However, + this behaviour is no different from e.g. <code>ArrayList</code>. + </p><p> + You may safely presume that the hashCode implementation used will not change between versions of lombok, however this guarantee is not set in stone; + if there's a significant performance improvement to be gained from using an alternate hash algorithm, that will be substituted in a future version. + </p><p> + For the purposes of equality, 2 <code>NaN</code> (not a number) values for floats and doubles are considered equal, eventhough 'NaN == NaN' would + return false. This is analogous to <code>java.lang.Double</code>'s equals method, and is in fact required to ensure that comparing an object + to an exact copy of itself returns <code>true</code> for equality. + </p><p> + If there is <em>any</em> method named either <code>hashCode</code> or <code>equals</code>, regardless of parameters or return type, + that method will not be generated, and a warning is emitted instead. <code>hashCode</code> and <code>equals</code> need to be in sync with + each other, which lombok cannot guarantee if it is only generating one of the two methods, hence you always get a warning if one <em>or</em> both + of the methods already exist. + </p><p> + Attempting to exclude fields that don't exist or would have been excluded anyway (because they are static) results in warnings on the named fields. + You therefore don't have to worry about typos. + </p> + </div> + </div> + <div class="footer"> + <a href="index.html">Back to features</a> | <a href="ToString.html">Previous feature (@ToString)</a> | <a href="Data.html">Next feature (@Data)</a><br /> + <a href="../credits.html" class="creditsLink">credits</a> | <span class="copyright">Copyright © 2009 Reinier Zwitserloot and Roel Spilker, licensed under the <a href="http://www.opensource.org/licenses/mit-license.php">MIT licence</a>.</span> + </div> + <div style="clear: both;"></div> + </div> +</div> +<script type="text/javascript"> + var gaJsHost = (("https:" == document.location.protocol) ? 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