Android Studio AlertDialog Customize - Java

MyDialogFragment.java

public class MyDialogFragment extends DialogFragment {

    @NonNull
    @Override
    public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
        /* 省略 */
    }

    @Override
    public void onStart() {
        super.onStart();
        AlertDialog alertDialog = (AlertDialog) getDialog();
        if (alertDialog != null) {
            alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setTextColor(Color.WHITE);
            alertDialog.getButton(AlertDialog.BUTTON_POSITIVE).setBackgroundColor(getResources().getColor(R.color.orange));
        }
    }
}