public class SmsReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {

    Bundle bundle = intent.getExtras();
    SmsMessage[] msg = null ;
    String msgStr = "";

    if ( bundle != null ){
        Object[] pdus = (Object[]) bundle.get ("pdus");
        msg = new SmsMessage [pdus.length] ;

        for( int i = 0; i<msg.length; i++){

            msg[i] = SmsMessage.createFromPdu((byte[]) pdus[i]);
            msgStr = msg[i].getDisplayOriginatingAddress();

        }

        Intent smsIntent =new Intent(context,MainActivity.class);
        smsIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        smsIntent.putExtra("msgStr",msgStr);
        context.startActivity(smsIntent);
    }

}

public class MainActivity extends AppCompatActivity {

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

    Intent sms_intent = getIntent();
    Bundle b = sms_intent.getExtras();

    if( b != null ){
       notificationCall(b.getString("sms_str"),"message");
    }
}

public void notificationCall(String title , String message){

    NotificationCompat.Builder notificationBuilder = (NotificationCompat.Builder) new NotificationCompat.Builder(this)
            .setDefaults(NotificationCompat.DEFAULT_ALL)
            .setSmallIcon(R.drawable.ic_launcher_background)
            .setContentTitle(title+"n")
            .setContentText(message);

  NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
  notificationManager.notify(1,notificationBuilder.build());
}