Android：如何检测Android的光线传感器是否被手遮盖

Question

I am a new Android developer and working on a fun project. I want to make the cell phone beeps for couple of seconds if the light sensor is covered. But I don't know what event is triggered when the light sensor is covered. Can some one give me a hint please what that event would be ?

public class MainActivity extends AppCompatActivity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    SensorManager sensorManager = (SensorManager) this.getSystemService(this.SENSOR_SERVICE);
    Sensor lightSensor = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
    ( some event ???) {
    // if some one coveres the light sensor then beep sound is played         
        ToneGenerator toneGen1 = new ToneGenerator(AudioManager.STREAM_MUSIC, 200);
        toneGen1.startTone(ToneGenerator.TONE_CDMA_ABBR_REORDER,15000);

    }
    if (lightSensor != null){
        Toast.makeText(this, "There is a sensor light ",
                Toast.LENGTH_SHORT).show();


    }
    else {
        // Failure! sensor not available.
        Toast.makeText(this, "No sensor light",
                Toast.LENGTH_SHORT).show();
    }


}

}

Answer 1

  use below code 

       SensorManager mySensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);

         Sensor LightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
float max =  lightSensor.getMaximumRange();
         if(LightSensor != null){
          textLIGHT_available.setText("Sensor.TYPE_LIGHT Available");
          mySensorManager.registerListener(
            LightSensorListener, 
            LightSensor, 
            SensorManager.SENSOR_DELAY_NORMAL);

         }else{
          //Sensor.TYPE_LIGHT NOT Available;
         }
        }

        private final SensorEventListener LightSensorListener
         = new SensorEventListener(){

       @Override
       public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

       }

       @Override
       public void onSensorChanged(SensorEvent event) {
        if(event.sensor.getType() == Sensor.TYPE_LIGHT){
         Toast.makeText(Activity.this,"LIGHT: " + event.values[0],Toast.LENGTH_SHORT).show();
if(event.values[0]/max<treashold)
{
//do here treasholde value is between 0 and 1
}
        }
       }

        };