next method
Load the data on the next page.
If there is no data, load() is executed.
Implementation
@override
Future<void> next() async {
if (!canNext) {
return;
}
final prevLength = length;
clear();
_nextCount = _nextCount + 1;
await load();
if (prevLength == length) {
_nextCount = _nextCount - 1;
}
}