Question

如何保存列表项的状态，以便我可以在重新启动手机时将其恢复。目前在下面的代码中，您可以看到我有一个列表视图，其中包含一个列表项。现在我想在onDestroy和onPause期间保存“items”的状态，并在onCreate期间检索回来（这样做的原因是在重新启动手机时检索数据状态）。有人可以帮助代码。

public class LogListView extends ListActivity {
    /** Called when the activity is first created. */
    private static String newString;
    private static EntryAdapter adapter;
    int clickCounter = 0;
    static ArrayList<Item> items = new ArrayList<Item>();
    static SharedPreferences preferences = null;
    private static Context context = null;
    static StringTokenizer tokens;
    private static String first;
    private static String second;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        context = this;
        adapter = new EntryAdapter(this, items);
        // items.add(new SectionItem("Log Report"));
        setListAdapter(adapter);

        if (adapter.getCount() != 0) {
            // Do nothing Adapter has value
        } else {
            Toast.makeText(LogListView.this, "No Items Available",Toast.LENGTH_SHORT).show();
            //Retrive Preference here when Adapter is null

        }

    }

    // Method which will handle dynamic insertion
    public static void addItems() {

        preferences = context.getSharedPreferences("LOG",android.content.Context.MODE_PRIVATE);
        newString = preferences.getString("log", "");

        tokens = new StringTokenizer(newString, ",");
        first = tokens.nextToken();
        second = tokens.nextToken();

        items.add(new EntryItem(first, second));
        adapter.notifyDataSetChanged();

    }
    // Method which will handle dynamic insertion ends

    @Override
    public void onDestroy() {
        super.onDestroy();

        //Save preference here


    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {

        if (!items.get(position).isSection()) {

            items.get(position);
            // Toast.makeText(this, "You clicked " + item.title ,
            // Toast.LENGTH_SHORT).show();
            Toast.makeText(this, "You clicked " + position, Toast.LENGTH_SHORT)
                    .show();

        }

        if (position == 9) {

        }

        super.onListItemClick(l, v, position, id);
    }
}

Answer 1

如果我必须将List保存到SharedPreferences，我总是选择执行以下操作，但是你需要使用Gson库。

首先将列表转换为JSON字符串：

Type listOfObjects = new TypeToken<List<YourObject>>(){}.getType();
String json = gson.toJson(list, listOfObjects);

然后将String保存到首选项。要将json转换回列表，请执行以下操作：

Type listOfObjects = new TypeToken<List<YourObject>>(){}.getType();
List<YourObject> list = gson.fromJson(json, listOfObjects);

如何在Android中保存和检索列表项

1 个答案: