Sensor compass

package com.example.nikit.compass;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
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.widget.ImageView;
import android.widget.TextView;

import static android.hardware.Sensor.TYPE_MAGNETIC_FIELD;

@SuppressLint("DefaultLocale")
public class MainActivity extends AppCompatActivity
        implements SensorEventListener {


    void registerSensor(int sensorType)
    {
        SensorManager senSensorManager =
                (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        Sensor sensor =
                senSensorManager.getDefaultSensor(
                        sensorType);
        senSensorManager.registerListener(this, sensor,
                SensorManager.SENSOR_DELAY_NORMAL);
    }
    Bitmap bm;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        registerSensor(Sensor.TYPE_MAGNETIC_FIELD);
        registerSensor(Sensor.TYPE_ACCELEROMETER);
        bm = BitmapFactory.decodeResource(
                getResources(), R.drawable.peka);
        ImageView imageView = findViewById(R.id.imageView);
        imageView.setImageBitmap(bm);
    }

    float [] magnetData = new float[3];
    float [] accelerationData = new float[3];
    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
            magnetData = event.values;
        else
            accelerationData = event.values;

        final TextView text = findViewById(R.id.hello);
        float[] rotation = new float[9];
        float[] compass = new float[3];
        SensorManager.getRotationMatrix(rotation, null,
                accelerationData, magnetData);
        SensorManager.getOrientation(rotation, compass);

        ImageView imageView = findViewById(R.id.imageView);
        Bitmap rotatedBitmap = rotateBitmap(bm,
                -compass[0] * 180 / 3.141592f);
        imageView.setImageBitmap(rotatedBitmap);
        text.setText(String.format("%f %f %f",
                compass[0], compass[1], compass[2]));
    }

    public static Bitmap rotateBitmap(Bitmap source, float angle)
    {
        Matrix matrix = new Matrix();
        matrix.postRotate(angle);
        return Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), matrix, true);
    }

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

    }
}