Sensor {flashLight}

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    //full information for sensor
    //https://guides.codepath.com/android/Listening-to-Sensors-using-SensorManager#sensors-in-the-background

    //TAG for log
    final static String TAG = "Sensor";
    //Sensor Managar to handle our all sensors
    private SensorManager sensorManager;
    //define sensor for light
    private Sensor flashLight;

    //create event listener to show when event that related to sensor has קרה
    private SensorEventListener sensorEventListener = new SensorEventListener() {
        @Override
        public void onSensorChanged(SensorEvent sensorEvent) {
            Toast.makeText(MainActivity.this, "onSensorChange:" + sensorEvent.toString(), Toast.LENGTH_LONG).show();
            Log.e(TAG, "onSensorChanged: " + sensorEvent.toString());
        }

        @Override
        public void onAccuracyChanged(Sensor sensor, int i) {
            Toast.makeText(MainActivity.this, "OnAccuracy changed:" + sensor.toString(), Toast.LENGTH_SHORT).show();
            Log.e(TAG, "onAccuracyChanged: " + sensor.toString());
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        //get the defualt sensor of specific type
        flashLight = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();
        if (flashLight != null) {
            sensorManager.registerListener(sensorEventListener, flashLight, SensorManager.SENSOR_DELAY_NORMAL);
        }
    }

    @Override
    protected void onPause() {
        if (flashLight != null) {
            sensorManager.unregisterListener(sensorEventListener);
        }
        super.onPause();
    }
}