更改对话框标题颜色

Question

我的类中有以下onResume（）函数，它扩展了AppCompatDialogFragment。 我只想在发生某种条件时才改变标题的颜色。我怎么能这样做？

public void onResume() {
    super.onResume();
    final AlertDialog dialog = (AlertDialog)getDialog();
    dialog.getButton(AlertDialog.BUTTON_POSITIVE).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String code = editTextCode.getText().toString();
            if(code.length() != 6 || !code.matches("[0-9A-F]+")){
                dialog.setTitle("Insert a valid 6 digit hexcode");
                //HERE I WANT TO CHANGE THE TITLE COLOR
                // AND DO SOMETHING LIKE dialog.setTitleColor(...)

            } else{
                listener.applyHex(code);
                dialog.dismiss();
            }
        }
    });
}