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<#import "../_features.html" as f>
<@f.scaffold title="@StandardException"
logline="TODO">
<@f.history>
<p>
<code>@StandardException</code> was introduced as an experimental feature in lombok v1.18.21.
</p>
</@f.history>
<@f.overview>
<p>
Put this annotation on your own exception types (new classes that <code>extends Exception</code> or anything else that inherits from <code>Throwable</code>. This annotation will then generate up to 4 constructors:
</p><ul>
<li>A no-args constructor (<code>MyException()</code>), representing no message, and no cause.</li>
<li>A message-only constructor (<code>MyException(String message)</code>), representing the provided message, and no cause.</li>
<li>A cause-only constructor (<code>MyException(Throwable cause)</code>), which will copy the message from the cause, if there is one, and uses the provided cause.</li>
<li>A full constructor (<code>MyException(String message, Throwable cause)</code>).</li>
</ul>
<p>
Each constructor forwards to the full constructor; you can write any or all of these constructors manually in which case lombok
will not generate it. The full constructor, if it needs to be generated, will invoke <code>super(message);</code> and will then
invoke <code>super.initCause(cause);</code> if the cause is not null.
</p><p>
There are few reasons <em>not</em> to put this annotation on all your custom exceptions.
</p>
</@f.overview>
<@f.snippets name="StandardException" />
<@f.confKeys>
<dt>
<code>lombok.standardException.addConstructorProperties</code> = [<code>true</code> | <code>false</code>] (default: <code>false</code>)
</dt><dt>
<code>lombok.standardException.flagUsage</code> = [<code>warning</code> | <code>error</code>] (default: not set)
</dt><dd>
Lombok will flag any usage of <code>@StandardException</code> as a warning or error if configured.
</dd>
</@f.confKeys>
<@f.smallPrint>
<p>
Lombok will not check if you extend an actual exception type.
</p><p>
Lombok does not require that the class you inherit from has the <code>Throwable cause</code> variants, because not all exceptions
have these. However, the `<code>Parent(String message)</code>` constructor as well as the no-args constructor <em>must</em> exist.
</p><p>
There is a very slight functional difference: Normally, invoking <code>new SomeException(message, null)</code> will initialize
the cause to be <em>no cause</em>, and this cannot be later changed by invoking <code>initCause</code>. However, lombok's
standard exceptions <strong>do</strong> let you overwrite an explicit no-cause with <code>initCause</code> later.
</p><p>
A second slight functional difference: Normally, invoking <code>new SomeException(cause)</code>, if implemented as <code>super(cause);</code>, will set the message to be equal to the message of the cause. However, lombok does not do this - it leaves the exception as having no message at all. We think inheriting the message is fundamentally wrong - messages are not guaranteed to be sensible in the absence of the context of the exception-type. The cause ought to be listed anywhere where it is relevant; if you are using messages as direct user feedback (which is rare, in the java community), <code>@StandardException</code> can't really help you anyway; the infrastructure of e.g. <code>getLocalizedMessage()</code> is too complicated.
</p>
</@f.smallPrint>
</@f.scaffold>
|
