android – 更改弹出对话框的背景颜色

这是对话框的代码：

mPrefs = PreferenceManager.getDefaultSharedPreferences(this);

    Boolean welcomeScreenShown = mPrefs.getBoolean(welcomeScreenShownPref, false);

    if (!welcomeScreenShown) {


        String whatsNewText = getResources().getString(R.string.Text);
        new AlertDialog.Builder(this).setMessage(whatsNewText).setPositiveButton(
                R.string.ok, new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
            }
        }).show();
        SharedPreferences.Editor editor = mPrefs.edit();
        editor.putBoolean(welcomeScreenShownPref, true);
        editor.commit(); // Very important to save the preference
    }

AlertDialog.Builder(this, AlertDialog.THEME_HOLO_LIGHT)...

要么

AlertDialog.Builder(this, AlertDialog.THEME_DEVICE_DEFAULT_LIGHT)...