如何通过C＃中的值将listView中的项目分组？

Question

I have a listView and I want to group items that share the same ID but different SysDate so that instead of showing multiple lines with the same value and different dates, I want to show multiple lines only when the ID changes.

Example:

From this:

ID | Sysdate
1  | 12:00
1  | 12:01
1  | 12:02
2  | 12:03
2  | 12:05

To this with only Sysdate changing for the same line:

ID | Sysdate
1  | 12:00
2  | 12:05

Like if the current item that's been added is the same as the one that already exists in the listview then only change the sysdate in the same line, if not then add that new line in the listview .

Answer 1

Your question as stated is unanswerable. There exists a concept of "grouping" in Windows ListView , (it is for example what you see in Windows Explorer if you open up "My Computer" and select "View" -> "Content",) but I do not think that's what you have in mind. And besides that concept of "grouping", there is no other defined "grouping" operation that can be performed on a ListView .

Your question does not help in defining what you mean by grouping, because for each group of ids (1,2) you have picked a sysdate to display arbitrarily. (For the case where id=1 you have picked 12:00, which is on the first row with id=1, but in the case where id=2 you have picked 12:05, which is on the second row with id=2.)

I would suggest that you consider grouping a property of your dataset, and not a property of the ListView . In other words, first think exactly what you mean by grouping, then come up with code that performs the grouping on your dataset, and then feed the ListView with the grouped dataset. The ListView cannot possibly know anything about your concept of grouping.

Answer 2

var obj = objTest.OrderBy(x => x.ID).GroupBy(x => x.ID).Select(g => new {g, count = g.Count()}).SelectMany(t => t.g.Select(b=>b).Zip(Enumerable.Range(t.count, 1), (j, i) => new {j.Sysdate, j.ID}));

Answer 3

If your dataobject has an ID and a sysdate, and thats how you show them, you can't group them. Now if your dataobject has an ID and a List of sysdates, you only get 1 occurance of each ID in your ListView and with each ID you get a List of sysdates. You will have to code your own ViewCell for this.

If you get your dataobjects from a query, you will have to format the dataobjects yourself.