如何让DialogFragment在activity main中更改文本？

<TextView
    android:id="@+id/textView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="初始文本"
    />

private TextView textView;

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

    textView = findViewById(R.id.textView);
}

public void showDialogFragment() {
    MyDialogFragment dialogFragment = new MyDialogFragment();
    dialogFragment.show(getSupportFragmentManager(), "dialog");
}

public interface OnTextChangeListener {
    void onTextChange(String newText);
}

OnTextChangeListener listener = (OnTextChangeListener) getActivity();
listener.onTextChange("新的文本");

public class MainActivity extends AppCompatActivity implements OnTextChangeListener {

    // ...

    @Override
    public void onTextChange(String newText) {
        textView.setText(newText);
    }
}