Saving Serializable Objects List into sharedPreferences

Easiest way out?

Convert to JSON and save it as a String.

Another good solution is to use GSON. Here's an example:

private static final String MAP = "map";    
private static final Type MAP_TYPE = new TypeToken<Map<MyObjA, MyObjB>>() {}.getType();

private static SharedPreferences prefs = MyApplication.getContext().getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);

private static Map<MyObjA, MyObjB> myMap;

public static void saveMap (Map<MyObjA, MyObjB> map) {
    SharedPreferences.Editor editor = prefs.edit();

    editor.putString(MAP, new Gson().toJson(map));
    editor.commit();
    myMap = map;
}

public static Map<MyObjA, MyObjB> loadMap() {
    if (myMap == null) {
        myMap = new Gson().fromJson(prefs.getString(MAP, null), MAP_TYPE);
    }
    return myMap;
}

More information about gson at http://code.google.com/p/google-gson/

Pretty simple right? ;)
Take care

You can use the JSON format to serialize your ArrayList and the objects it contains, and then store the String result into the SharedPreferences.

When you want to get the data back, retrieve the String and use a JSONArray to retrieve each object and add it to a new ArrayList.

Otherwise you can simply use Object(Input/Output)Stream classes and write it into a differente file using (for writing)

FileOutputStream fos = this.openFileOutput(fileName, MODE_PRIVATE);
final OutputStreamWriter osw = new OutputStreamWriter(fos);
JSONArray array = new JSONArray();

// Add your objects to the array

osw.write(array.toString());
osw.flush();
osw.close();