Create a BroadcastReceiver that accepts a callback to let us know the verification code has been received

SmsBroadcastReceiver.java

public class SmsBroadcastReceiver extends BroadcastReceiver {
  private final OnVerificationCodeReceivedListener codeReceivedListener;

  public SmsBroadcastReceiver(@NonNull OnVerificationCodeReceivedListener codeReceivedListener) {
    this.codeReceivedListener = codeReceivedListener;
  }

  @Override
  public void onReceive(Context context, Intent intent) {
    // TODO: See if this message is coming from the expected phone number
    // TODO: If so, parse the code out of the message and notify the callback
  }

  interface OnVerificationCodeReceivedListener {
    void onVerificationCodeReceived(String code);
  }
}