java Android - 如何从光标中删除项目？
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Android - how to delete item from a cursor?
提问by JDS
Let's say I make the following cursor to get the call log of someone:
假设我使用以下光标来获取某人的通话记录：
String[] strFields = {
android.provider.CallLog.Calls.NUMBER,
android.provider.CallLog.Calls.TYPE,
android.provider.CallLog.Calls.CACHED_NAME,
android.provider.CallLog.Calls.CACHED_NUMBER_TYPE
};
String strOrder = android.provider.CallLog.Calls.DATE + " DESC";
Cursor mCallCursor = getContentResolver().query(
android.provider.CallLog.Calls.CONTENT_URI,
strFields,
null,
null,
strOrder
);
Now how would I go about deleted the ith item in this cursor? This could also be a cursor getting list of music, etc. So then I must ask - is this even possible? I can understand for certain cursors that 3rd party apps wouldn't be allowed to delete from.
现在我将如何删除该游标中的第 i 个项目？这也可能是获取音乐列表等的光标。所以我必须问 - 这甚至可能吗？我可以理解某些游标不允许 3rd 方应用程序从中删除。
Thanks.
谢谢。
回答by MikeWallaceDev
Sorry mate you can't delete from a cursor.
抱歉，您无法从光标中删除。
You must either use your ContentResolver or a SQL call of some sort..
您必须使用 ContentResolver 或某种 SQL 调用。
回答by Glenn Bech
You can to a trick with a MatrixCursor. With this strategy, you copy the cursor, and leave out the one row you want to exclude. This is - obviously, not very efficient for large cursors as you will keep the entire dataset in memory.
您可以使用 MatrixCursor 来解决问题。使用此策略，您可以复制游标，并省略要排除的一行。这 - 显然，对于大型游标不是很有效，因为您会将整个数据集保存在内存中。
You also have to repeat the String array of column names in the constructor of the MatrixCursor. You should keep this as a Constant.
您还必须在 MatrixCursor 的构造函数中重复列名的 String 数组。你应该把它作为一个常量。
//TODO: put the value you want to exclude
String exclueRef = "Some id to exclude for the new";
MatrixCursor newCursor = new MatrixCursor(new String[] {"column A", "column B");
if (cursor.moveToFirst()) {
do {
// skip the copy of this one ....
if (cursor.getString(0).equals(exclueRef))
continue;
newCursor.addRow(new Object[]{cursor.getString(0), cursor.getString(1)});
} while (cursor.moveToNext());
}
I constantly battle with this; trying to make my apps with cursors and content providers only, keeping away from object mapping as long as I can. You should see some of my ViewBinders ... :-)
我不断地与这个斗争；尝试仅使用游标和内容提供程序制作我的应用程序，尽可能远离对象映射。你应该看到我的一些 ViewBinders ... :-)
