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<h3 class="sectionHead"><span class="titlemark">4 </span> <a
id="x17-170004"></a>DBusSignal</h3>
<!--l. 330--><p class="noindent" >Signals are also declared as part of an interface. The Java API models these
as inner classes within an interface. The containing interface must extend
<span
class="cmtt-12">DBusInterface</span>, and the inner classes representing the signals must extend
<span
class="cmtt-12">DBusSignal</span><span class="footnote-mark"><a
href="dbus-java18.html#fn10x0"><sup class="textsuperscript">10</sup></a></span><a
id="x17-17001f10"></a> .
The Signal name is derived from the name of this inner class, and the interface from its
containing interface.
</p><!--l. 337--><p class="indent" > Signals can take parameters as methods can (although they cannot return anything). For
the reflection to work, a Signal declare a single constructor of the correct type. The
constructor must take the object path they are being emitted from as their first
(String) argument, followed by the other parameters in order. They must also call the
superclass constructor with the same parameters. A full definition of a signal can
be seen in figure <a
href="#x17-170035">5<!--tex4ht:ref: fig:signal --></a>. Again, more complicated definitions are available in the test
classes<span class="footnote-mark"><a
href="dbus-java19.html#fn11x0"><sup class="textsuperscript">11</sup></a></span><a
id="x17-17002f11"></a> .
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<a
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<!--l. 348--><p class="noindent" >
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<div class="verbatim" id="verbatim-11">
package org.freedesktop;
 <br />import org.freedesktop.dbus.DBusInterface;
 <br />import org.freedesktop.dbus.DBusSignal;
 <br />import org.freedesktop.dbus.exceptions.DBusException;
 <br />
 <br />public interface DBus extends DBusInterface
 <br />{
 <br />   public class NameAcquired extends DBusSignal
 <br />   {
 <br />      public final String name;
 <br />      public NameAcquired(String path, String name)
 <br />                              throws DBusException
 <br />      {
 <br />         super(path, name);
 <br />         this.name = name;
 <br />      }
 <br />   }
 <br />}
</div>
<!--l. 368--><p class="nopar" ></p></div>
<br /> <div class="caption"
><span class="id">Figure 5: </span><span
class="content">A Signal with one parameter</span></div><!--tex4ht:label?: x17-170035 -->
</div><hr class="endfigure" />
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