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3. java code
A. 要使用感應器，就必須要在Activity上implements SensorEventListener，並且利用Eclipse實作出onAccuracyChanged與onSensorChanged。
public class OlaTeach_SensorOnly extends Activity implements SensorEventListener{
@Override
public void onSensorChanged(SensorEvent event) {
// TODO Auto-generated method stub
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// TODO Auto-generated method stub
}
}