我有一个RecyclerView – 网格,拖动和使用这个
code我已经设法实现了,并做了很多变化,只有一个问题,我不能保存拖动的项目位置重新启动(应用程序不是手机).
我想到的是在我的item.java构造函数中添加“int position”,但我不能做的就是获得改变的位置.
我想到的是在我的item.java构造函数中添加“int position”,但我不能做的就是获得改变的位置.
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);
}
};
以下是onCreate中的代码：
ItemTouchHelper ith = new ItemTouchHelper(_ithCallback);
ith.attachToRecyclerView(RcView);
@Override
public void onStop()
{
super.onStop();
SharedPreferencesTools.setOrderedItems(this,AllItems);
}
getAllItemList：
private List<Item> getAllItemList(){
AllItems = SharedPreferencesTools.getOrderedItems(this);
//Add item .. etc
//return items
}
解决方法
只需将修改后的收藏AllItems保存在SharedPreferences中,并将其加载到应用程序开始&一旦您退出应用程序,就将其存储起来.
为此,您需要将您的集合序列化为json,并将其存储为String.然后反序列化：
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);
}
}
使用这两种方法：
SharedPreferencesTools.setOrderedItems(getActivity(),AllItems); ... List<Item> AllItems = SharedPreferencesTools.getOrderedItems(getActivity());
