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<title>Chapter 10. Annotations</title><meta name="generator" content="DocBook XSL Stylesheets V1.76.1"><link rel="home" href="index.html" title="FindBugs™ Manual"><link rel="up" href="index.html" title="FindBugs™ Manual"><link rel="prev" href="analysisprops.html" title="Chapter 9. Analysis Properties"><link rel="next" href="rejarForAnalysis.html" title="Chapter 11. Using rejarForAnalysis"></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 10. Annotations</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="analysisprops.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="rejarForAnalysis.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 10. Annotations"><div class="titlepage"><div><div><h2 class="title"><a name="annotations"></a>Chapter 10. Annotations</h2></div></div></div><p>
<span class="application">FindBugs</span> supports several annotations to express the developer's intent
so that FindBugs can issue warnings more appropriately. You need to use
Java 5 to use annotations, and must place the annotations.jar and jsr305.jar
files in the classpath while compiling your program.
</p><div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.CheckForNull</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Field, Method, Parameter
<p>
The annotated element might be null, and uses of the element should check for null.
When this annotation is applied to a method it applies to the method return value.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.CheckReturnValue</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Method, Constructor
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>priority:</strong></span>The priority of the warning (HIGH, MEDIUM, LOW, IGNORE). Default value:MEDIUM.
</p><p>
<span class="command"><strong>explanation:</strong></span>A textual explaination of why the return value should be checked. Default value:"".
</p></dd></dl></div><p>
This annotation is used to denote a method whose return value should always be checked after invoking the method.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.DefaultAnnotation</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Type, Package
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>Annotation class objects. More than one class can be specified.
</p><p>
<span class="command"><strong>priority:</strong></span>Default priority(HIGH, MEDIUM, LOW, IGNORE). Default value:MEDIUM.
</p></dd></dl></div><p>
Indicates that all members of the class or package should be annotated with the default
value of the supplied annotation classes. This would be used for behavior annotations
such as @NonNull, @CheckForNull, or @CheckReturnValue. In particular, you can use
@DefaultAnnotation(NonNull.class) on a class or package, and then use @Nullable only
on those parameters, methods or fields that you want to allow to be null.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.DefaultAnnotationForFields</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Type, Package
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>Annotation class objects. More than one class can be specified.
</p><p>
<span class="command"><strong>priority:</strong></span>Default priority(HIGH, MEDIUM, LOW, IGNORE). Default value:MEDIUM.
</p></dd></dl></div><p>
This is same as the DefaultAnnotation except it only applys to fields.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.DefaultAnnotationForMethods</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Type, Package
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>Annotation class objects. More than one class can be specified.
</p><p>
<span class="command"><strong>priority:</strong></span>Default priority(HIGH, MEDIUM, LOW, IGNORE). Default value:MEDIUM.
</p></dd></dl></div><p>
This is same as the DefaultAnnotation except it only applys to methods.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.DefaultAnnotationForParameters</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Type, Package
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>Annotation class objects. More than one class can be specified.
</p><p>
<span class="command"><strong>priority:</strong></span>Default priority(HIGH, MEDIUM, LOW, IGNORE). Default value:MEDIUM.
</p></dd></dl></div><p>
This is same as the DefaultAnnotation except it only applys to method parameters.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.NonNull</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Field, Method, Parameter
<p>
The annotated element must not be null.
Annotated fields must not be null after construction has completed. Annotated methods must have non-null return values.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.Nullable</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Field, Method, Parameter
<p>
The annotated element could be null under some circumstances. In general, this means
developers will have to read the documentation to determine when a null value is
acceptable and whether it is neccessary to check for a null value. FindBugs will
treat the annotated items as though they had no annotation.
</p><p>
In pratice this annotation is useful only for overriding an overarching NonNull
annotation.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.OverrideMustInvoke</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Method
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>Specify when the super invocation should be
performed (FIRST, ANYTIME, LAST). Default value:ANYTIME.
</p></dd></dl></div><p>
Used to annotate a method that, if overridden, must (or should) be invoke super
in the overriding method. Examples of such methods include finalize() and clone().
The argument to the method indicates when the super invocation should occur:
at any time, at the beginning of the overriding method, or at the end of the overriding method.
(This anotation is not implmemented in FindBugs as of September 8, 2006).
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.PossiblyNull</strong></span></span></dt><dd><p>
This annotation is deprecated. Use CheckForNull instead.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.SuppressWarnings</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Type, Field, Method, Parameter, Constructor, Package
<div class="variablelist"><dl><dt><span class="term"><span class="command"><strong>[Parameter]</strong></span></span></dt><dd><p>
<span class="command"><strong>value:</strong></span>The name of the warning. More than one name can be specified.
</p><p>
<span class="command"><strong>justification:</strong></span>Reason why the warning should be ignored. Default value:"".
</p></dd></dl></div><p>
The set of warnings that are to be suppressed by the compiler in the annotated element.
Duplicate names are permitted. The second and successive occurrences of a name are ignored.
The presence of unrecognized warning names is <span class="emphasis"><em>not</em></span> an error: Compilers
must ignore any warning names they do not recognize. They are, however, free to emit a
warning if an annotation contains an unrecognized warning name. Compiler vendors should
document the warning names they support in conjunction with this annotation type. They
are encouraged to cooperate to ensure that the same names work across multiple compilers.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.UnknownNullness</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Field, Method, Parameter
<p>
Used to indicate that the nullness of the target is unknown, or my vary in unknown ways in subclasses.
</p></dd><dt><span class="term"><span class="command"><strong>edu.umd.cs.findbugs.annotations.UnknownNullness</strong></span></span></dt><dd><span class="command"><strong>[Target]</strong></span> Field, Method, Parameter
<p>
Used to indicate that the nullness of the target is unknown, or my vary in unknown ways in subclasses.
</p></dd></dl></div><p>
<span class="application">FindBugs</span> also supports the following annotations:
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">net.jcip.annotations.GuardedBy</li><li class="listitem">net.jcip.annotations.Immutable</li><li class="listitem">net.jcip.annotations.NotThreadSafe</li><li class="listitem">net.jcip.annotations.ThreadSafe</li></ul></div><p>
</p><p>
You can refer the JCIP annotation <a class="ulink" href="http://jcip.net/annotations/doc/index.html" target="_top">
API documentation</a> at <a class="ulink" href="http://jcip.net/" target="_top">Java Concurrency in Practice</a>.
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