如何获得光传感器的价值

Question

I have following code uses light sensor but not able to display value of event.value[0]...it displays toast only with message "On SensorChanged" also text is not set to tv where i goes wrong..

here is code

    public void onSensorChanged(SensorEvent event) 
    {
    if( event.sensor.getType() == Sensor.TYPE_LIGHT)
    {
        tv.setText("value: " + event.values[0] + " lux" );   
        Toast.makeText(getApplicationContext(),"On SensorChanged"+ event.values[0],Toast.LENGTH_SHORT).show();
        Log.d("Sensor Changed", "onSensor Change :" + brightness);
    }

}

Answer 1

Galaxy S does in fact have light-sensor hardware.
The proximity sensing is done by the light sensor device. More on this here .

To ensure that you are activating and using the light sensor properly,
verify that getSensorList(TYPE_LIGHT) returns a valid light sensor.

Thereafter proceed as shown in this link .

Answer 2

I dont think that is contains light sensors to that why it is returning nothing,your code seems fine otherwise,

http://www.gsmarena.com/samsung-phones-9.php

Follow this link to check the model you are testing on and see in features and then sensors

Answer 3

Now i get sensor value. But the problem is how to assign that to System.SCREEN_BRIGHTNESS. i use following code but not able to assign it. It only works when automatic is enable in brightness setting.

following is the code

public void onSensorChanged(SensorEvent event) 
{
    if( event.sensor.getType() == Sensor.TYPE_LIGHT)
    {
        float currentLux = event.values[0];
        brightness=(int)event.values[0];
        brightbar.setProgress(brightness);
        tv2=(TextView)findViewById(R.id.textView2);
        tv2.setText("value:"+ currentLux+ " lux" );   
        System.putFloat(cResolver, System.SCREEN_BRIGHTNESS_MODE,currentLux);
        android.view.WindowManager.LayoutParams layoutpars = window.getAttributes();
        layoutpars.screenBrightness = currentLux;  
        window.setAttributes(layoutpars); 
        Log.d("Sensor Changed", "onSensor Change :" + currentLux);
    }

}

Answer 4

Have you registered the listener. There are three parts for using the sensors

1. Create SensorManager and Sensors

    public class MainActivity extends AppCompatActivity implements SensorEventListener { private SensorManager mSensorManager = null; private Sensor mLightSensor = null; ... protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); mLightSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT); } 

2. Register the sensor you are listening to

    @Override protected void onResume() { super.onResume(); mSensorManager.registerListener(this, mLightSensor, SensorManager.SENSOR_DELAY_NORMAL); } 

3. Implement the SensorEventListener methods from part 1.

    @Override public void onSensorChanged(SensorEvent sensorEvent) { if( sensorEvent.sensor.getType() == Sensor.TYPE_LIGHT) { Log.d("SensorTest", ""+ sensorEvent.values[0]); } } @Override public void onAccuracyChanged(Sensor sensor, int i) { }