[code]
protected void onCreate(Bundle savedInstanceState) {

......

// start motion detection
sensorMgr=(SensorManager) getSystemService(SENSOR_SERVICE);
sensorMgr.registerListener(this, sensorMgr.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL);
}

public void onAccuracyChanged(Sensor s, int arg1) {
// TODO Auto-generated method stub
}

@Override
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType()==Sensor.TYPE_ACCELEROMETER){

long curTime = System.currentTimeMillis();

// only allow one update every 100ms.
if ((curTime - lastUpdate) > 100) {
long diffTime = (curTime - lastUpdate);
lastUpdate = curTime;

x = event.values[0];
y = event.values[1];
z = event.values[2];

float speed = Math.abs(x+y+z - last_x - last_y - last_z) / diffTime * 10000;
if (speed > SHAKE_THRESHOLD) {
// yes, this is a shake action! Do something about it!

}
last_x = x;
last_y = y;
last_z = z;
}
}
}

@Override
protected void onPause() {
if (sensorMgr != null) {
sensorMgr.unregisterListener(this);
sensorMgr = null;
}
super.onPause();
}
[/code]