Android code to detect when the user is lowering the device v2

MainActivity.java

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

public class MainActivity extends AppCompatActivity implements SensorEventListener {

    private float[] gravity = new float[0];
    private float[] magnetic = new float[0];
    private int inclination;
    private final int SENSITIVITY = -1;

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

        SensorManager sm = (SensorManager) getSystemService(SENSOR_SERVICE);
        sm.registerListener(this, sm.getDefaultSensor
                (Sensor.TYPE_GRAVITY), SensorManager.SENSOR_DELAY_NORMAL);
        sm.registerListener(this, sm.getDefaultSensor
                (Sensor.TYPE_MAGNETIC_FIELD), SensorManager.SENSOR_DELAY_NORMAL);
    }


    @Override
    public void onSensorChanged(SensorEvent event) {
        float[] rotArray = new float[9];
        float[] inclArray = new float[9];

        switch (event.sensor.getType()) {
            case Sensor.TYPE_GRAVITY:
                gravity = new float[]{event.values[0], event.values[1], event.values[2]};
                break;
            case Sensor.TYPE_MAGNETIC_FIELD:
                magnetic = new float[]{event.values[0], event.values[1], event.values[2]};
                break;
        }
        if (gravity.length == 3 && magnetic.length == 3) {
            SensorManager.getRotationMatrix(rotArray, inclArray, gravity, magnetic);
            float prevInclination = inclination;
            inclination = (int) Math.round(Math.toDegrees(Math.acos(rotArray[8])));

            if (inclination - prevInclination < SENSITIVITY) {
                Log.d("Movement", "Going Down!");
            }
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int i) {

    }
}