Android setSringSet() / getStringSet() with compatibility

Utilities.java

public static void setPersistentObjectSet(Context context, String key, String o) {
    if (initStore(context)) {
        synchronized (_store) {
            SharedPreferences.Editor editor = _store.edit();
            if (o == null) {
                editor.remove(key);
            } else {
                Set<String> vals = null;
                if (VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                    vals = _store.getStringSet(key, null);
                } else {
                    String s = _store.getString(key, null);
                    if(s != null)
                        vals = new HashSet<String>(Arrays.asList(s.split(",")));
                }
                if (vals == null) vals = new HashSet<String>();
                vals.add(o);
                if (VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                    editor.putStringSet(key, vals);
                } else {
                    editor.putString(key, join(vals, ","));
                }
            }
            editor.commit();
        }
    }
}


public static Set<String> getPersistentObjectSet(Context context, String key) {
    if (initStore(context)) {
        synchronized (_store) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
                return _store.getStringSet(key, null);
            } else {
                String s = _store.getString(key, null);
                if (s != null) return new HashSet<String>(Arrays.asList(s.split(",")));
                else return null;
            }
        }
    } return null;
}



public static String join(Set<String> set, String delim) {
    StringBuilder sb = new StringBuilder();
    String loopDelim = "";

    for (String s : set) {
        sb.append(loopDelim);
        sb.append(s);

        loopDelim = delim;
    }

    return sb.toString();
}