Have you not done mobile paging yet? ? When mobile paging involves changing data, it must not be based on page=1, otherwise it will be repeated or missed. (It’s okay to miss it, you will find it after repeating it on the client)
The general solution is as follows:
First of all, you must have a sorting, such as by time, score, etc. If the client wants to go to the next page, it only needs to pass the identifier of the last record of the current page. The server will get this identifier and search for the next one. of data to it.
Example:
Suppose the server data is 1,2,3,4,5,6,7,8 and the data returned to the client is 1,2,3. If the data after 3 is needed, 3 will be sent back to the server. The server gets 3 and then according to the agreed logic, it finds 4, 5, 6 which are larger than 3 and gives them to the client. In this way, even if it is added or deleted, there will be no duplication problem. In the past, this is how we did waterfall flow picture display. In addition, FB, instagram Many APIs are designed like this

no=1 If you have any, look for no=2

You don’t use a database, so why does the data disappear?
Is paging possible? According to the list you saved. Similar to the following pseudo code:
`
List<x> list1 = list.subList(0,3);
List&lt ;x> list2 = list.subList(3,6);
List<x> list3 = list.subList(6,9);
`

It is really troublesome when the data in the paginated list is deleted...

There are 3 solutions to consider:

1. If the amount of data is small, don’t do paging, just give all the data in the list to the client at once

2. If the amount of data is large and it is necessary to paginate, you can consider not only passing the data of the page you want to obtain each time, but also passing the diff (changes) of the data of the page that has been obtained previously to the client

3. If the data changes, send a flag indicating that the data has changed to the client, allowing the client to refresh the entire list or prompt the user to refresh the entire list.

First sort the collection of students by id, and then use the id and size of the last data in the previous request as the input parameters of the request for paging. The id here is Student.no.

for(Student student:students){
  if(student.no>lastId){
      result.add(student);
      if(result.size()==size){
          return result;
      }
  }
}