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package cgeo.geocaching.utils;
import android.os.Handler;
import android.os.Message;
/**
* A PeriodicHandler class helps with the implementation of a periodic
* action embedded in a thread with a looper such as the UI thread.
* The act() method will be called periodically. The clock may drift
* as the implementation does not target real-time actions.
*
* The handler will be interrupted if the device goes to sleep.
*
*/
abstract public class PeriodicHandler extends Handler {
final static private int START = 0;
final static private int STOP = 1;
final static private int ACT = 2;
final private long period;
/**
* Create a new PeriodicHandler object.
*
* @param period
* The period in milliseconds.
*/
public PeriodicHandler(final long period) {
this.period = period;
}
/**
* Subclasses of PeriodicHandler must implement this method.
*/
abstract public void act();
@Override
public void handleMessage(final Message msg) {
switch (msg.what) {
case START:
removeMessages(ACT);
sendEmptyMessage(ACT);
break;
case STOP:
removeMessages(ACT);
break;
case ACT:
sendEmptyMessageDelayed(ACT, period);
act();
}
}
/**
* Start the periodic handler.
*
* Restarting a handler that is already started will only
* reset its clock.
*/
public void start() {
sendEmptyMessage(START);
}
/**
* Stop the periodic handler.
*
* If this method is called from the looper thread, this call is
* guaranteed to be synchronous.
*/
public void stop() {
sendMessageAtFrontOfQueue(obtainMessage(STOP));
}
}
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