<!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>@Log (and friends)</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>@Log (and friends)</h1> <div class="byline">Captain's Log, stardate 24435.7: "What was that line again?"</div> <div class="overview"> <h3>Overview</h3> <p> <em>NEW in lombok 0.10: </em>You can annotate any class with a log annotation to let lombok generate a logger field.<br /> The logger is named <code>log</code> and field's type depends on which logger you have selected. </p><p> There are four choices available:<br /> <dl> <dt><code>@CommonsLog</code></dt> <dd>Creates <code><span class="keyword">private static final </span><a href="http://commons.apache.org/logging/apidocs/org/apache/commons/logging/Log.html">org.apache.commons.logging.Log</a> <span class="staticfield">log</span> = <a href="http://commons.apache.org/logging/apidocs/org/apache/commons/logging/LogFactory.html#getLog(java.lang.Class)">org.apache.commons.logging.LogFactory.getLog</a>(LogExample.<span class="keyword">class</span>);</code></dd> <dt><code>@Log</code></dt> <dd>Creates <code><span class="keyword">private static final </span><a href="http://download.oracle.com/javase/6/docs/api/java/util/logging/Logger.html">java.util.logging.Logger</a> <span class="staticfield">log</span> = <a href="http://download.oracle.com/javase/6/docs/api/java/util/logging/Logger.html#getLogger(java.lang.String)">java.util.logging.Logger.getLogger</a>(LogExample.<span class="keyword">class</span>.getName());</code></dd> <dt><code>@Log4j</code></dt> <dd>Creates <code><span class="keyword">private static final </span><a href="http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Logger.html">org.apache.log4j.Logger</a> <span class="staticfield">log</span> = <a href="http://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/Logger.html#getLogger(java.lang.Class)">org.apache.log4j.Logger.getLogger</a>(LogExample.<span class="keyword">class</span>);</code></dd> <dt><code>@Slf4j</code></dt> <dd>Creates <code><span class="keyword">private static final </span><a href="http://www.slf4j.org/api/org/slf4j/Logger.html">org.slf4j.Logger</a> <span class="staticfield">log</span> = <a href="http://www.slf4j.org/apidocs/org/slf4j/LoggerFactory.html#getLogger(java.lang.Class)">org.slf4j.LoggerFactory.getLogger</a>(LogExample.<span class="keyword">class</span>);</code></dd> </dl> </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> If a field called <code>log</code> already exists, a warning will be emitted and no code will be generated. </p><p> A future feature of lombok's diverse log annotations is to find calls to the logger field and, if the chosen logging framework supports it and the log level can be compile-time determined from the log call, guard it with an <code>if</code> statement. This way if the log statement ends up being ignored, the potentially expensive calculation of the log string is avoided entirely. This does mean that you should <em>NOT</em> put any side-effects in the expression that you log. </p> </div> </div> <div class="footer"> <a href="index.html">Back to features</a> | <a href="SneakyThrows.html">Previous feature (@SneakyThrows)</a> | <a href="val.html">Next feature (val)</a><br /> <a href="../credits.html" class="creditsLink">credits</a> | <span class="copyright">Copyright © 2009-2011 Reinier Zwitserloot, Roel Spilker and Robbert Jan Grootjans, licensed under the <a href="http://www.opensource.org/licenses/mit-license.php">MIT license</a>.</span> </div> <div style="clear: both;"></div> </div> </div> <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); </script> <script type="text/javascript"> try { var pageTracker = _gat._getTracker("UA-9884254-1"); pageTracker._trackPageview(); } catch(err) {} </script> </body></html>