Determine light level, Sensor.TYPE_LIGHT.

Example to determine light level using Android light sensor:

package com.example.androidsensor;

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.app.Activity;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 TextView textLIGHT_available, textLIGHT_reading;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        textLIGHT_available 
         = (TextView)findViewById(R.id.LIGHT_available);
        textLIGHT_reading 
         = (TextView)findViewById(R.id.LIGHT_reading);
     
     SensorManager mySensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
     
     Sensor LightSensor = mySensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
     if(LightSensor != null){
      textLIGHT_available.setText("Sensor.TYPE_LIGHT Available");
      mySensorManager.registerListener(
        LightSensorListener, 
        LightSensor, 
        SensorManager.SENSOR_DELAY_NORMAL);
      
     }else{
      textLIGHT_available.setText("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){
     textLIGHT_reading.setText("LIGHT: " + event.values[0]);
    }
   }
     
    };

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world"
        tools:context=".MainActivity" />
    
    <TextView
        android:id="@+id/LIGHT_available"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />
    <TextView
        android:id="@+id/LIGHT_reading"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

Related:
- Access temperature sensor, TYPE_TEMPERATURE and TYPE_AMBIENT_TEMPERATURE.