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<TITLE>Implementing a Simple Event Notifier
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<h3>
e334.
Implementing a Simple Event Notifier</h3>
The <code>Observer</code> and <code>Observable</code> classes are superseded by a more
elaborate event framework (see <a href="../java.util/CustEvent.html" class="eglink"><font size="-1"><b>e333</b> Creating a Custom Event</font></a>).
However, these two classes can still be useful for implementing a
simple event notifier.
<pre>
// Declare the model
class MyModel extends Observable {
// The setChanged() protected method must overridden to make it public
public synchronized void setChanged() {
super.setChanged();
}
}
</pre>
<pre>
// Create the model
MyModel model = new MyModel();
// Register for events
model.addObserver(new Observer() {
public void update(Observable o, Object arg) {
}
});
// Indicate that the model has changed
model.setChanged();
// Fire an event to all the views
Object arg = <font color="#0066ff"><i>"some information about the event"</i></font>;
model.notifyObservers(arg);
</pre>
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Related Examples
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e331. <a class="eglink" href="GenRandom.html?l=rel">
Generating a Random Number
</a>
<br>
e332. <a class="eglink" href="ParseString.html?l=rel">
Breaking a String into Words
</a>
<br>
e333. <a class="eglink" href="CustEvent.html?l=rel">
Creating a Custom Event
</a>
<br>
e335. <a class="eglink" href="GetAllLocales.html?l=rel">
Listing All Available Locales
</a>
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e336. <a class="eglink" href="SetDefLocale.html?l=rel">
Setting the Default Locale
</a>
<br>
e337. <a class="eglink" href="ValueOnObj.html?l=rel">
Associating a Value with an Object
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See also:
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Arrays">
Arrays
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Bits">
Bits
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Collections">
Collections
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Dates">
Dates
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Hash%20Tables">
Hash Tables
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Lists">
Lists
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Property%20Files">
Property Files
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sets">
Sets
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Sorted%20Collections">
Sorted Collections
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Time">
Time
</a>
<a class="eglink" href="/egs/java.util/pkg.html?l=rel#Timers">
Timers
</a>
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