Save an arraylist of Strings to shared preferences

Question

What is the best way to save an ArrayList of strings to SharedPreferences in API level 8? The only way i can think of now is to save all of the str

Answer 1

If you are using an api (like level 8) where you cant use put/getStringSet(), then this is a possible solution, but this is very expensive and not flexible if you want to store bigger lists. I mean creating a map like datastructure for a simple array-like structure creates a huge overhead, if preformance is important.

To save it:

public static void writeList(Context context, List list, String prefix)
{
    SharedPreferences prefs = context.getSharedPreferences("YourApp", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();

    int size = prefs.getInt(prefix+"_size", 0);

    // clear the previous data if exists
    for(int i=0; i

To retrieve it:

public static List readList (Context context, String prefix)
{
    SharedPreferences prefs = context.getSharedPreferences("YourApp", Context.MODE_PRIVATE);

    int size = prefs.getInt(prefix+"_size", 0);

    List data = new ArrayList(size);
    for(int i=0; i

And to actually use it:

List animals = new ArrayList();
animals.add("cat");
animals.add("bear");
animals.add("dog");

writeList(someContext, animals, "animal");

And to retrieve it:

List animals = readList (someContext, "animal");

If you are not limited to use SharedPreferences, consider using SQLiteDatabase!