1<html> 2<head> 3<title>FindBugs FAQ</title> 4<link rel="stylesheet" type="text/css" href="findbugs.css"> 5 6</head> 7 8<body> 9 10<table width="100%"><tr> 11 12 13<td bgcolor="#b9b9fe" valign="top" align="left" width="20%"> 14<table width="100%" cellspacing="0" border="0"> 15<tr><td><a class="sidebar" href="index.html"><img src="umdFindbugs.png" alt="FindBugs"></a></td></tr> 16 17<tr><td> </td></tr> 18 19<tr><td><b>Docs and Info</b></td></tr> 20<tr><td><font size="-1"><a class="sidebar" href="findbugs2.html">FindBugs 2.0</a></font></td></tr> 21<tr><td><font size="-1"><a class="sidebar" href="demo.html">Demo and data</a></font></td></tr> 22<tr><td><font size="-1"><a class="sidebar" href="users.html">Users and supporters</a></font></td></tr> 23<tr><td><font size="-1"><a class="sidebar" href="http://findbugs.blogspot.com/">FindBugs blog</a></font></td></tr> 24<tr><td><font size="-1"><a class="sidebar" href="factSheet.html">Fact sheet</a></font></td></tr> 25<tr><td><font size="-1"><a class="sidebar" href="manual/index.html">Manual</a></font></td></tr> 26<tr><td><font size="-1"><a class="sidebar" href="ja/manual/index.html">Manual(ja/日本語)</a></font></td></tr> 27<tr><td><font size="-1"><a class="sidebar" href="FAQ.html">FAQ</a></font></td></tr> 28<tr><td><font size="-1"><a class="sidebar" href="bugDescriptions.html">Bug descriptions</a></font></td></tr> 29<tr><td><font size="-1"><a class="sidebar" href="mailingLists.html">Mailing lists</a></font></td></tr> 30<tr><td><font size="-1"><a class="sidebar" href="publications.html">Documents and Publications</a></font></td></tr> 31<tr><td><font size="-1"><a class="sidebar" href="links.html">Links</a></font></td></tr> 32 33<tr><td> </td></tr> 34 35<tr><td><a class="sidebar" href="downloads.html"><b>Downloads</b></a></td></tr> 36 37<tr><td> </td></tr> 38 39<tr><td><a class="sidebar" href="http://www.cafeshops.com/findbugs"><b>FindBugs Swag</b></a></td></tr> 40 41<tr><td> </td></tr> 42 43<tr><td><b>Development</b></td></tr> 44<tr><td><font size="-1"><a class="sidebar" href="http://sourceforge.net/tracker/?group_id=96405">Open bugs</a></font></td></tr> 45<tr><td><font size="-1"><a class="sidebar" href="reportingBugs.html">Reporting bugs</a></font></td></tr> 46<tr><td><font size="-1"><a class="sidebar" href="contributing.html">Contributing</a></font></td></tr> 47<tr><td><font size="-1"><a class="sidebar" href="team.html">Dev team</a></font></td></tr> 48<tr><td><font size="-1"><a class="sidebar" href="api/index.html">API</a> <a class="sidebar" href="api/overview-summary.html">[no frames]</a></font></td></tr> 49<tr><td><font size="-1"><a class="sidebar" href="Changes.html">Change log</a></font></td></tr> 50<tr><td><font size="-1"><a class="sidebar" href="http://sourceforge.net/projects/findbugs">SF project page</a></font></td></tr> 51<tr><td><font size="-1"><a class="sidebar" href="http://code.google.com/p/findbugs/source/browse/">Browse source</a></font></td></tr> 52<tr><td><font size="-1"><a class="sidebar" href="http://code.google.com/p/findbugs/source/list">Latest code changes</a></font></td></tr> 53</table> 54</td> 55 56<td> 57<h1>FindBugs FAQ</h1> 58 59<p> This document contains answers to frequently asked questions about 60<a href="index.html">FindBugs</a>. If you just want general 61information about FindBugs, have a look at the 62<a href="factSheet.html">fact sheet</a> and the 63<a href="manual/index.html">manual</a>. 64 65<h2>Contents</h2> 66<ol> 67<li> <a href="#q1">I'm getting java.lang.UnsupportedClassVersionError when I try to run FindBugs</a> 68<li> <a href="#q2">When I click the "Find Bugs!" button, I get a NoSuchMethodError or VerifyError</a> 69<li> <a href="#q3">FindBugs is running out of memory, or is taking a long time to finish</a> 70<li> <a href="#q4">What is the "auxiliary classpath"? Why should I specify it?</a> 71<li> <a href="#q5">The Eclipse plugin doesn't load</a> 72<li> <a href="#q6">I'm getting a lot of false "OS" and "ODR" warnings</a> 73<li> <a href="#q7">The Eclipse plugin loads, but doesn't work correctly</a> 74<li> <a href="#q8">Where is the Maven plugin for FindBugs?</a> 75<li> <a href="#q9">Where is the NetBeans plugin for FindBugs?</a> 76</ol> 77 78<h2><a name="q1">Q1: I'm getting java.lang.UnsupportedClassVersionError when I try to run FindBugs</a></h2> 79 80<p> FindBugs requires JRE 1.5.0 or later to run. If you use an earlier version, 81you will see an exception error message similar to the following: 82<pre> 83Exception in thread "main" java.lang.UnsupportedClassVersionError: 84edu/umd/cs/findbugs/gui/FindBugsFrame (Unsupported major.minor version 48.0) 85</pre> 86The solution is to upgrade to JRE 1.5.0 or later. 87 88<h2><a name="q2">Q2: When I click the "Find Bugs!" button, I get a NoSuchMethodError or VerifyError</a></h2> 89 90<p> The symptom of this bug is that when you start the FindBugs analysis, 91you see an exception similar to the following: 92<pre> 93java.lang.NoSuchMethodError: org.apache.bcel.Repository.setRepository(Lorg/apache/bcel/util/Repository;)V 94 at edu.umd.cs.findbugs.FindBugs.clearRepository(FindBugs.java:483) 95 ... 96</pre> 97 98or 99 100<pre> 101java.lang.VerifyError: Cannot inherit from final class 102 at java.lang.ClassLoader.defineClass0(Native Method) 103 at java.lang.ClassLoader.defineClass(ClassLoader.java:537) 104 ... 105</pre> 106 107<p> The problem here is that the wrong version of the 108<a href="http://jakarta.apache.org/bcel/">Apache BCEL</a> 109library is being found. FindBugs requires its own 110version of BCEL, which normally will be used automatically 111when you invoke the <code>findbugs</code> or <code>findbugs.bat</code> 112scripts used to launch FindBugs. If an old version of BCEL is installed 113in a location, such as "lib/endorsed" in the JRE installation, 114where it overrides classes on the application classpath, 115FindBugs will not execute properly. 116We know of several reasons this could happen 117 118<ul> 119<li> If you install the 120<a href="http://java.sun.com/webservices/downloads/webservicespack.html">Java(TM) Web Services 121Developer Pack 1.2</a> 122in the <code>lib/endorsed</code> directory of your Java Runtime Environment (JRE). 123The file <code>xsltc.jar</code> contains an old version of BCEL that is incompatible with 124FindBugs. 125 126<li> Another possibility is that you are using the IBM JDK. 127Some versions include a version of BCEL which conflicts with the 128one required by FindBugs. This problem is fixed in version 1.4.1 SP1, 129so upgrading your JDK should allow FindBugs to run correctly. 130 131<li> Some versions of the Apache Xalan XSLT processor include 132an old version of BCEL in <code>xalan.jar</code>. 133 134</ul> 135 136<p> In all of these cases, you should be able to run FindBugs 137by either removing the offending version of BCEL from your JRE, 138or installing a clean JRE or JDK and using that to run FindBugs. 139 140<p> Many thanks to Peter Meulmeester, Michael Levi, and Thomas Klaeger 141for providing information on this problem. 142 143<h2><a name="q3">Q3: FindBugs is running out of memory, or is taking a long time to finish</a></h2> 144 145<p> In general, FindBugs requires lots of memory and a relatively 146fast CPU. For large applications, 512M or more of heap space may be 147required. By default, FindBugs allocates 256M of heap space. 148You can increase this using the <code>-maxHeap <i>n</i></code> option, 149where <i>n</i> is the number of megabytes of heap space to allocate. 150 151 152<h2><a name="q4">Q4: What is the "auxiliary classpath"? Why should I specify it?</a></h2> 153 154<p> Many important facts about a Java class require information about 155the classes that it references. For example: 156<ul> 157<li> What other classes and interfaces the class inherits from 158<li> What exceptions can be thrown by methods in external classes 159and interfaces 160</ul> 161 162<p> The "auxiliary classpath" is a list of Jar files, directories, and 163class files containing classes that are <em>used</em> by the code you 164want FindBugs to analyze, but should not themselves be analyzed 165by FindBugs. 166 167<p> If FindBugs doesn't have complete information about referenced classes, 168it will not be able to produce results that are as accurate as possible. 169For example, having a complete repository of referenced classes allows 170FindBugs to prune control flow information so it can concentrate on 171paths through methods that are most likely to be feasible at runtime. 172Also, some bug detectors (such as the suspicious reference comparison detector) 173rely on being able to perform type inference, which requires complete 174type hierarchy information. 175 176<p> For these reasons, we strongly recommend that you completely specify 177the auxiliary classpath when you run FindBugs. You can do this 178by using the <code>-auxclasspath</code> command line option, or the 179"Classpath entries" list in the GUI project editor dialog. 180 181<p> If FindBugs cannot find a class referenced by your application, it 182will print out a message when the analysis completes, specifying the 183classes that were missing. You should modify the auxiliary classpath 184to specify how to find the missing classes, and then run FindBugs again. 185 186<h2><a name="q5">Q5: The Eclipse plugin doesn't load</a></h2> 187 188<p> The symptom of this problem is that Eclipse fails to load 189the FindBugs UI plugin with the message: 190<blockquote> 191Plug-in "edu.umd.cs.findbugs.plugin.eclipse" was disabled due to missing or disabled 192prerequisite plug-in "org.eclipse.ui.ide" 193</blockquote> 194 195<p> The reason for this problem is that the Eclipse 196plugin distributed with FindBugs 197does not work with older 3.x versions of Eclipse. 198Please use Eclipse version 3.6 (June 2010) or newer. 199 200<h2><a name="q6">Q6: I'm getting a lot of false "OS" and "ODR" warnings</a></h2> 201 202<p> By default, FindBugs assumes that any method invocation can 203throw an unchecked runtime exception. As a result, 204it may assume that an unchecked exception thrown out of the 205method could bypass a call to a <code>close()</code> method 206for a stream or database resource. 207 208<p> You can use the <code>-workHard</code> command line argument 209or the <code>findbugs.workHard</code> boolean analysis property 210to make FindBugs work harder to prune unlikely exception 211edges. This generally reduces the number of 212false warnings, at the expense of slowing down the 213analysis. 214 215<h2><a name="q7">Q7: The Eclipse plugin loads, but doesn't work correctly</a></h2> 216 217<p> Make sure the Java code you trying to analyze is built properly and has no 218classpath or compile errors. 219 220<p> Make sure the project and workspace FindBugs settings are valid - in doubt, revert them to defaults. 221 222<p> Make sure the Error log view does not show errors. 223 224<h2><a name="q8">Q8: Where is the Maven plugin for FindBugs?</a></h2> 225 226<p> 227The <a href="http://maven.apache.org/">Maven</a> Plugin for FindBugs 228may be found <a href="http://mojo.codehaus.org/findbugs-maven-plugin/">here</a>. 229Please note that the Maven plugin is not maintained by the FindBugs developers, 230so we can't answer questions about it. 231</p> 232 233<h2><a name="q9">Q9: Where is the NetBeans plugin for FindBugs?</a></h2> 234 235<p>We recommend <a href="http://kenai.com/projects/sqe/pages/Home">SQE: Software Quality Environment</a> 236which bundles FindBugs, PMD and CheckStyle. Use the following 237update site: 238<a href="http://deadlock.netbeans.org/hudson/job/sqe/lastStableBuild/artifact/build/full-sqe-updatecenter/updates.xml 239">http://deadlock.netbeans.org/hudson/job/sqe/lastStableBuild/artifact/build/full-sqe-updatecenter/updates.xml</a> 240<p>Pease note that the SQE plugin is not maintained by the FindBugs developers, 241so we can't answer questions about it. 242</p> 243 244 245<hr> <p> 246<script language="JavaScript" type="text/javascript"> 247<!---//hide script from old browsers 248document.write( "Last updated "+ document.lastModified + "." ); 249//end hiding contents ---> 250</script> 251<p> Send comments to <a class="sidebar" href="mailto:findbugs@cs.umd.edu">findbugs@cs.umd.edu</a> 252<p> 253<A href="http://sourceforge.net"><IMG src="http://sourceforge.net/sflogo.php?group_id=96405&type=5" width="210" height="62" border="0" alt="SourceForge.net Logo" /></A> 254 255</td> 256 257</table> 258 259</body> 260 261</html> 262
