我有一个RecyclerView - Grid,带有拖放功能。 drop,使用这个code我已经设法实现了这一点,并做了很多改变,只有一个问题,我无法在重启时保存被拖动的项目位置(应用程序不是手机)。 我想到的是将“int position”添加到我的item.java构造函数中,但我不能做的是获得更改的位置。
我正在使用相同的拖拽和放大器删除链接中提供的代码。
ItemTouchHelper.Callback _ithCallback = new ItemTouchHelper.Callback() {
//and in your imlpementaion of
public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
// get the viewHolder's and target's positions in your adapter data, swap them
Collections.swap(AllItems, viewHolder.getAdapterPosition(), target.getAdapterPosition());
// and notify the adapter that its dataset has changed
rcAdapter.notifyItemMoved(viewHolder.getAdapterPosition(), target.getAdapterPosition());
return true;
}
@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
//TODO
}
//defines the enabled move directions in each state (idle, swiping, dragging).
@Override
public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
return makeFlag(ItemTouchHelper.ACTION_STATE_DRAG,
ItemTouchHelper.DOWN | ItemTouchHelper.UP | ItemTouchHelper.START | ItemTouchHelper.END);
}
};
这是onCreate中的代码:
ItemTouchHelper ith = new ItemTouchHelper(_ithCallback);
ith.attachToRecyclerView(RcView);
在更改位置后获取重复项目,代码:
@Override
public void onStop()
{
super.onStop();
SharedPreferencesTools.setOrderedItems(this, AllItems);
}
getAllItemList:
private List<Item> getAllItemList(){
AllItems = SharedPreferencesTools.getOrderedItems(this);
//Add item .. etc
//return items
}
答案 0 :(得分:7)
只需将修改后的收藏集AllItems
保留在SharedPreferences
中,然后将其加载到应用开始时间&amp;一旦你离开应用程序,就把它存回来。
为此,您需要按Gson
将集合序列化为json并存储为String
。然后将其反序列化:
public final class SharedPreferencesTools {
private static final String USER_SETTINGS_PREFERENCES_NAME = "UserSettings";
private static final String ALL_ITEMS_LIST = "AllItemsList";
private static Gson gson = new GsonBuilder().create();
public static List<Item> getOrderedItems(Context context) {
String stringValue = getUserSettings(context).getString(ALL_ITEMS_LIST, "");
Type collectionType = new TypeToken<List<Item>>() {
}.getType();
List<Item> result = gson.fromJson(stringValue, collectionType);
return (result == null) ? new ArrayList<Item>() : result;
}
public static void setOrderedItems(Context context, List<Item> items) {
String stringValue = gson.toJson(items);
SharedPreferences sharedPreferences = getUserSettings(context);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putString(ALL_ITEMS_LIST, stringValue);
editor.apply();
}
static SharedPreferences getUserSettings(Context context) {
return context.getSharedPreferences(USER_SETTINGS_PREFERENCES_NAME, Context.MODE_PRIVATE);
}
}
这两种方法的用法:
SharedPreferencesTools.setOrderedItems(getActivity(), AllItems);
...
List<Item> AllItems = SharedPreferencesTools.getOrderedItems(getActivity());