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<title>org.eclipse.equinox.util.timer</title>
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<p>This package adds the Timer Service by
adding two additional interfaces. The idea is the Timer Service
to provide universal timers which can be used by other bundles if
they need them. When the Util Bundle is started, the Timer
Service is registered and started, too. To use the Timer Service,
you have to get it from the Bundle Context. </p>

<p>To create a timer, you must invoke Timer's method <i>notifyAfter(listener,
timePeriod, event)</i> and pass correct parameters to it. </p>

<blockquote>
    <p><i>listener</i> is object of a class implementing the<i>
    TimerListener</i> interface whose <i>time(event)</i> method
    will be invoked after the given <i>timePeriod</i> (in seconds)
    with event specified in the <i>notifyAfter</i> method. The
    Timer Service makes an event queue from all started timer
    listeners and when some <i>timePeriod</i> of them passes, it
    invokes its timer method with specified <i>event</i> and
    removes it from queue. If the <i>notifyAfter</i> method is
    invoked with listener and event that already exist in queue,
    the previous listener is removed and the new one replaces it.</p>
</blockquote>

<blockquote>
    <p><i>event</i> is an int parameter. When more than one timer
    is started with the same listener, <i>event</i> shows which
    of them is to be notified.</p>
</blockquote>

<p>With the <i>removeLisener(listener, event)</i> method it is
possible to remove a listener with the specified event from the
queue before its <i>timePeriod</i> has passed. If the listener
with the specified event is not found, nothing happens. <br>
&nbsp; </p>

<blockquote>
    <p>Here is an example which starts 3 timers with diferent
    timerPeriod. The timer with lisener lsn1 and event 1 will be
    started again with diferent timePeriod, the Timer Service
    will remove the previous timer and only new one will stay in
    the queue. The timer with lisener lsn2 and event 2 will be
    removed from the queue befor its timePeriod has passed. Only
    timer with lisener lsn1, timePeriod 5 sec and event 1 will be
    notified by the Timer Service when its timePeriod has passed.</p>
</blockquote>

<table border="1" width="100%" cols="1">
    <tr>
        <td width="100%" nowrap><blockquote>
            <p>&nbsp; <br>
            <font size="2" face="Courier New">public class
            TestTimer { <br>
            &nbsp; private BundleContext bc; <br>
            &nbsp; private ServiceReference timerReference; <br>
            &nbsp; private Timer timer; </font></p>
            <p><font size="2" face="Courier New">&nbsp;public
            TestTimer(BundleContext bc) { <br>
            &nbsp;&nbsp;&nbsp; try { <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; this.bc = bc; <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; timerReference = bc.getServiceReference(&quot;org.eclipse.equinox.util.timer.Timer&quot;);
            <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (timerReference !=
            null) { <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; timer = (Timer)bc.getService(timerReference);
            <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            setTimerIntervals();&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; } <br>
            &nbsp;&nbsp;&nbsp; } catch (Exception e) { <br>
            &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; System.out.println(&quot;An
            error in start method.\n &quot; + e); <br>
            &nbsp;&nbsp;&nbsp; } <br>
            &nbsp; }&nbsp; <br>
            &nbsp;&nbsp; <br>
            &nbsp; private void setTimerIntervals() { <br>
            &nbsp;&nbsp;&nbsp; int t;&nbsp; //timePeriod <br>
            &nbsp;&nbsp;&nbsp; int e;&nbsp; //event <br>
            &nbsp;&nbsp;&nbsp;&nbsp; <br>
            &nbsp;&nbsp;&nbsp; //create lsn1 lisener implementing
            TimerLisener interface <br>
            &nbsp;&nbsp;&nbsp; TestTimerListener lsn1 = new
            TestTimerListener(); <br>
            &nbsp;&nbsp;&nbsp; t = 10; <br>
            &nbsp;&nbsp;&nbsp; e = 1; <br>
            &nbsp;&nbsp;&nbsp; //start timer interval <br>
            &nbsp;&nbsp;&nbsp; timer.notifyAfter(lsn1, t, e); <br>
            &nbsp;&nbsp;&nbsp; System.out.println(&quot;Timer
            with lisener lsn1 was started - timePeriod &quot; + t
            + &quot; sec, event &quot; + e); <br>
            &nbsp;&nbsp;&nbsp;&nbsp; <br>
            &nbsp;&nbsp;&nbsp; //create lsn2 lisener implementing
            TimerLisener interface <br>
            &nbsp;&nbsp;&nbsp; TestTimerListener lsn2 = new
            TestTimerListener(); <br>
            &nbsp;&nbsp;&nbsp; t = 12; <br>
            &nbsp;&nbsp;&nbsp; e = 2; <br>
            &nbsp;&nbsp;&nbsp; //start timer interval <br>
            &nbsp;&nbsp;&nbsp; timer.notifyAfter(lsn2, t, e); <br>
            &nbsp;&nbsp;&nbsp; System.out.println(&quot;Timer
            with lisener lsn2 was started - timePeriod &quot; + t
            + &quot; sec, event &quot; + e); </font></p>
            <p><font size="2" face="Courier New">&nbsp;&nbsp;&nbsp;
            t = 5; <br>
            &nbsp;&nbsp;&nbsp; e = 1; <br>
            &nbsp;&nbsp;&nbsp; //start timer interval <br>
            &nbsp;&nbsp;&nbsp; timer.notifyAfter(lsn1, t, e); <br>
            &nbsp;&nbsp;&nbsp; System.out.println(&quot;Timer
            with lisener lsn1 was started - timePeriod &quot; + t
            + &quot; sec, event &quot; + e); <br>
            &nbsp;&nbsp;&nbsp; System.out.println(&quot;\n&quot;);
            <br>
            &nbsp;&nbsp;&nbsp;&nbsp; <br>
            &nbsp;&nbsp;&nbsp; //remove lsn2 lisener with event 1
            <br>
            &nbsp;&nbsp;&nbsp; e = 2; <br>
            &nbsp;&nbsp;&nbsp; timer.removeListener(lsn2, e);&nbsp;&nbsp;
            <br>
            &nbsp; }&nbsp; <br>
            &nbsp;&nbsp; <br>
            }&nbsp;&nbsp; <br>
            &nbsp;</font></p>
        </blockquote>
        </td>
    </tr>
</table>

<blockquote>
    <p>The TestTimerListener class implements the TimerListener
    interface and its method timer(event) will be invoked every
    time a timerPeriod passes.</p>
</blockquote>

<table border="1" width="100%" cols="1">
    <tr>
        <td><blockquote>
            <p><font size="2" face="Courier New">&nbsp; <br>
            public class TestTimerListener implements
            TimerListener { <br>
            &nbsp;&nbsp; <br>
            &nbsp; public TestTimerListener() { <br>
            &nbsp; } <br>
            &nbsp;&nbsp; <br>
            &nbsp; public void timer(int event){ <br>
            &nbsp;&nbsp;&nbsp; System.out.println(&quot;Timer
            with event &quot; + event + &quot; has ended&quot;); <br>
            &nbsp; }&nbsp;&nbsp; <br>
            }</font></p>
        </blockquote>
        </td>
    </tr>
</table>

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