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Reinier Zwitserloot
96 lines
6.5 KiB
HTML
96 lines
6.5 KiB
HTML
<!DOCTYPE html>
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<html><head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<link rel="stylesheet" type="text/css" href="../logi/reset.css" />
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<link rel="stylesheet" type="text/css" href="features.css" />
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<link rel="shortcut icon" href="../favicon.ico" type="image/x-icon" />
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<meta name="description" content="Spice up your java" />
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<title>@Data</title>
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</head><body><div id="pepper">
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<div class="minimumHeight"></div>
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<div class="meat">
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<div class="header"><a href="../index.html">Project Lombok</a></div>
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<h1>@Data</h1>
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<div class="byline">All together now: A shortcut for <code>@ToString</code>, <code>@EqualsAndHashCode</code>,
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<code>@Getter</code> on all fields, and <code>@Setter</code> on all non-final fields. You even
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get a free constructor to initialize your final fields!</div>
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<div class="overview">
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<h3>Overview</h3>
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<p>
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<code>@Data</code> is a convenient shortcut annotation that bundles the features of <a href="ToString.html"><code>@ToString</code></a>,
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<a href="EqualsAndHashCode.html"><code>@EqualsAndHashCode</code></a> and <a href="GetterSetter.html"><code>@Getter</code> / <code>@Setter</code></a>
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together: In other words, <code>@Data</code> generates <em>all</em> the boilerplate that is normally associated with simple POJOs
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(Plain Old Java Objects) and beans: getters for all fields, setters for all non-final fields, and appropriate <code>toString</code>, <code>equals</code>
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and <code>hashCode</code> implementations that involve the fields of the class. In addition, <code>@Data</code> generates a constructor that
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initializes all final fields, as well as all non-final fields with no initializer that have been marked with <code>@NonNull</code> or <code>@NotNull</code>,
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in order to ensure the field is never null.
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</p><p>
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<code>@Data</code> is like having implicit <code>@ToString</code> and <code>@EqualsAndHashCode</code> annotations on the class.
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However, the parameters of <code>@ToString</code> and <code>@EqualsAndHashCode</code> (such as <code>callSuper</code>, <code>includeFieldNames</code> and
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<code>exclude</code>) cannot be set with <code>@Data</code>. If you need to set non-default values for any of these parameters, just add those annotations
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explicitly; <code>@Data</code> is smart enough to defer to those annotations.
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</p><p>
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All generated getters and setters will be <code>public</code>. To override the access level, annotate the field with an explicit <code>@Setter</code> and/or
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<code>@Getter</code> annotation. You can also use this annotation (by combining it with <code>AccessLevel.NONE</code>) to suppress generating a getter and/or setter
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altogether.
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</p><p>
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All fields marked as <code>transient</code> will not be considered for <code>hashCode</code> and <code>equals</code>. All static fields will be
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skipped entirely (not considered for any of the generated methods, and no setter/getter will be made for them).
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</p><p>
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If the class already contains a method with the same name as any method that would normally be generated, that method is not generated, and no warning or
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error is emitted. For example, if you already have a method with signature <code>void hashCode(int a, int b, int c)</code>, no <code>int hashCode()</code>
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method will be generated, even though technically <code>int hashCode()</code> is an entirely different method. The same rule applies to the constructor,
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<code>toString</code>, <code>equals</code>, and all getters and setters.
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</p><p>
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<code>@Data</code> can handle generics parameters for fields just fine. In order to reduce the boilerplate when constructing objects for classes with
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generics, you can use the <code>staticConstructor</code> parameter to generate a private constructor, as well as a static method that returns a new
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instance. This way, javac will infer the variable name. Thus, by declaring like so: <code>@Data(staticConstructor="of") class Foo<T> { private T x;}</code>
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you can create new instances of <code>Foo</code> by writing: <code>Foo.of(5);</code> instead of having to write: <code>new Foo<Integer>(5);</code>.
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</p>
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</div>
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<div class="snippets">
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<div class="pre">
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<h3>With Lombok</h3>
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<div class="snippet">@HTML_PRE@</div>
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</div>
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<div class="sep"></div>
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<div class="post">
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<h3>Vanilla Java</h3>
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<div class="snippet">@HTML_POST@</div>
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</div>
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</div>
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<div style="clear: left;"></div>
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<div class="overview">
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<h3>Small print</h3><div class="smallprint">
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<p>See the small print of <a href="ToString.html"><code>@ToString</code></a>, <a href="EqualsAndHashCode.html"><code>@EqualsAndHashCode</code></a> and
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<a href="GetterSetter.html"><code>@Getter / @Setter</code></a>.
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</p><p>
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Any annotations named <code>@NonNull</code> (case insensitive) on a field are interpreted as: This field must not ever hold
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<em>null</em>. Therefore, these annotations result in an explicit null check in the generated constructor for the provided field. Also, these
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annotations (as well as any annotation named <code>@Nullable</code>) are copied to the constructor parameter, in both the true constructor and
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any static constructor. The same principle applies to generated getters and setters (see the documentation for <a href="GetterSetter.html">@Getter / @Setter</a>)
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</p><p>
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By default, any variables that start with a $ symbol are excluded automatically.
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You can include them by specifying an explicit annotation (<code>@Getter</code> or <code>@ToString</code>, for example) and using the 'of' parameter.
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</p>
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</div>
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</div>
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<div class="footer">
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<a href="index.html">Back to features</a> | <a href="EqualsAndHashCode.html">Previous feature (@EqualsAndHashCode)</a> | <a href="Cleanup.html">Next feature (@Cleanup)</a><br />
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<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 license</a>.</span>
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<div style="clear: both;"></div>
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