easy way to save a LinkedList in a Android Application?

Question

what is the easyest or native way to save a list of objects in a android application?

i need to save it and then load it when the app starts again.

would be nice

Answer 1

I usually don't provide full answers, but since it's in my clipboard...

This should work with any List implementation.

Further you'll need to to define / exchange Constants.EXTERNAL_CACHE_DIR and might want to use something else than the UI-Thread for production.

 public static void persistList(final List<String> listToPersist, final String fileName) {
    FileWriter writer = null;
    BufferedWriter bufferedWriter = null;
    File outFile = new File(Constants.EXTERNAL_CACHE_DIR, fileName);
    try {
      if (outFile.createNewFile()) {
        writer = new FileWriter(outFile);
        bufferedWriter = new BufferedWriter(writer);
        for (String item : listToPersist) {
          bufferedWriter.write(item + "\n");
        }
        bufferedWriter.close();
        writer.close();
      }
    } catch (IOException ioe) {
      Log.w(TAG, "Exception while writing to file", ioe);
    }
  }

  public static List<String> readList(final String fileName) {
    List<String> readList = new ArrayList<String>();
    try {
      FileReader reader = new FileReader(new File(Constants.EXTERNAL_CACHE_DIR, fileName));
      BufferedReader bufferedReader = new BufferedReader(reader);
      String current = null;
      while ((current = bufferedReader.readLine()) != null) {
        readList.add(current);
      }
    } catch (FileNotFoundException e) {
      Log.w(TAG, "Didn't find file", e);
    } catch (IOException e) {
      Log.w(TAG, "Error while reading file", e);
    }
    return readList;
  }

Answer 2

Have u tried shared preferneces..? when ur app is about to exit, save that using shared preferences and again when app starts, load that preference.

Answer 3

Let your items stored in the LinkedList implement Parcelable so you can put them in your bundle. The in onSaveInstance you can put your objects in the bundle using:

bundle.putParcelableArrayList ("key", list);

and in onRestoreInstanceState of your Activity get the data back from that bundle using :

bundle.getParcelableArrayList();