Android的CursorLoader有选择和selectionArgs两个[] [英] Android CursorLoader with selection and selectionArgs[]
问题描述
我使用装载机
为 RecyclerView.Adapter
列表项。我想列出从数据库表中特定项目。所以,我所做的:
I am using Loader
for RecyclerView.Adapter
to list items. I want to list specific items from database table. So i did:
public Loader<Cursor> onCreateLoader(int id, Bundle args) {
String selectionArgs1[]={"1","13","14"};
String selection1 = DatabaseOpenHelper.COLUMN_ID + " in (";
for (int i = 0; i < selectionArgs1.length; i++) {
selection1 += "?, ";
}
selection1 = selection1.substring(0, selection1.length() - 2) + ")";
String[] projection1 =...
return new CursorLoader(getActivity(),StudentContentProvider.CONTENT_URI1, projection1, selection1,selectionArgs1, null);
}
通常我给 NULL,NULL
到选
和 selectionArgs两个
但在这里,我列出具体标识
项目。当新的项目添加到表,我想列出这问题就出现了。在光标
我是回不知道新的项目,因为我给了3特定项目,所以它只是检测时,有变化的那些3项。
如何列出当被加入了一些 ID
新项目,我想列出来呢?我应该从项目数据库中的所有项目 RecyclerView.Adapter
和 onBindViewHolder过滤
标识
()
Normally i give null,null
to selection
and selectionArgs
but here, i list items with specific IDs
. Problem arises when new item is added to table and i want to list it. The cursor
i am returning is not aware of new item since i gave 3 specific items, so it just detects when there is change on those 3 items.
How to list when there is new item added with some ID
and i want to list it too ? Should i project all items from database to RecyclerView.Adapter
and filter IDs
in onBindViewHolder()
?
推荐答案
既然我已经限制标识
在光标
,如果只有该特定项改变它被改变,而不是当添加新的项目。我做了 onLoadFinished()
一招,创造新的光标
和交换新的光标。因此,当有变化,我得到我的选择新的游标
和 selectionArgs两个
又说:
Since I have restricted IDs
in cursor
, it is changed if only that specific items change, not when new item is added. I did a trick on onLoadFinished()
to create new cursor
and swap that new cursor. So when there is change, I get new cursor with my selection
and selectionArgs
again:
public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
switch (loader.getId()) {
case LOADER_ID:{
String selectionArgs1[]={...};
String selection1 = DatabaseOpenHelper.COLUMN_ID + " in (";
for (int i = 0; i < selectionArgs1.length; i++) {
selection1 += "?, ";
}
selection1 = selection1.substring(0, selection1.length() - 2) + ")";
String[] projection1 =...
mDataset1 = getActivity().getContentResolver().query(StudentContentProvider.CONTENT_URI1, projection1, selection1, selectionArgs1, null);
mAdapter.swapCursor(mDataset1);
break;
}
}
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