Tidak dapat memulai dialog di kelas saya yang memperluas GcmListenerService

Saya mencoba membuat dialog ketika saya menerima jenis pesan tertentu di kelas saya yang meluas GcmListenerService

public class MyGcmListenerService extends GcmListenerService {

@Override
public void onMessageReceived(String from, Bundle data) {

    final String senderName = data.getString("sender");
    final String message = data.getString("message");

    if(senderName != null && senderName.equals("XXX")){
       final AlertDialog.Builder builder = new AlertDialog.Builder(this);

        builder.setMessage(message)
                .setTitle("Alert!")
                .setIcon(android.R.drawable.ic_dialog_alert)
                .setPositiveButton("Ok", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.dismiss();
                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        // User cancelled the dialog
                        dialog.dismiss();
                    }
                });
        try {
            new Thread() {
                @Override
                public void run() {
                    Looper.prepare();
                    final AlertDialog alertDialog = builder.create();
                    alertDialog.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);
                    alertDialog.show();
                    Looper.loop();

                }
            }.start();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }

tetapi saya mendapat pengecualian java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.

di baris ini final AlertDialog alertDialog = builder.create();

Aktivitas utama saya

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    final Toolbar toolbar =(Toolbar) findViewById(R.id.mainActivityBar);
     setSupportActionBar(toolbar);
    //other statements and methods here
}

Manifes.xml saya

 <activity
        android:name=".MainActivity"
        android:label="@string/title_activity_main"
        android:theme="@style/mainActivityTheme">
    </activity>

Sumber daya gaya saya

<style name="mainActivityTheme" parent="Theme.AppCompat.NoActionBar">
    <item name="windowActionBar">false</item>
    <item name="android:windowNoTitle">true</item>
    <item name="android:textColorSecondary">@android:color/white</item>
    <item name="android:windowActionBar">false</item>
</style>

Di mana saya melakukannya dengan cara yang salah?