Implementers of <code>Listener</code> provide a simple
<code>handleEvent()</code> method that is used internally
by SWT to dispatch events.
<p>
After creating an instance of a class that implements this interface
it can be added to a widget using the
<code>addListener(int eventType, Listener handler)</code> method and
removed using the
<code>removeListener (int eventType, Listener handler)</code> method.
When the specified event occurs, <code>handleEvent(...)</code> will
be sent to the instance.
</p>
<p>
Classes which implement this interface are described within SWT as
providing the <em>untyped listener</em> API. Typically, widgets will
also provide a higher-level <em>typed listener</em> API, that is based
on the standard <code>java.util.EventListener</code> pattern.
</p>
<p>
Note that, since all internal SWT event dispatching is based on untyped
listeners, it is simple to build subsets of SWT for use on memory
constrained, small footprint devices, by removing the classes and
methods which implement the typed listener API.
</p>
Implementers of <code>Listener</code> provide a simple <code>handleEvent()</code> method that is used internally by SWT to dispatch events. <p> After creating an instance of a class that implements this interface it can be added to a widget using the <code>addListener(int eventType, Listener handler)</code> method and removed using the <code>removeListener (int eventType, Listener handler)</code> method. When the specified event occurs, <code>handleEvent(...)</code> will be sent to the instance. </p> <p> Classes which implement this interface are described within SWT as providing the <em>untyped listener</em> API. Typically, widgets will also provide a higher-level <em>typed listener</em> API, that is based on the standard <code>java.util.EventListener</code> pattern. </p> <p> Note that, since all internal SWT event dispatching is based on untyped listeners, it is simple to build subsets of SWT for use on memory constrained, small footprint devices, by removing the classes and methods which implement the typed listener API. </p>
@see Widget#addListener @see java.util.EventListener @see org.eclipse.swt.events