如果arraylist为空，我如何保存到shredpreferences？

import android.content.SharedPreferences;
import android.preference.PreferenceManager;

SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);

SharedPreferences.Editor editor = sharedPreferences.edit();

StringBuilder stringBuilder = new StringBuilder();
for (String item : arrayList) {
    stringBuilder.append(item).append(",");
}
String arrayString = stringBuilder.toString();

editor.putString("arrayListKey", arrayString);
editor.apply();

SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);

String arrayString = sharedPreferences.getString("arrayListKey", "");

ArrayList<String> arrayList = new ArrayList<>();
if (!arrayString.isEmpty()) {
    String[] items = arrayString.split(",");
    Collections.addAll(arrayList, items);
}