[List] Dynamic number of list items

[patrickfrei]

Description: The M3 Catalog app contains several List examples. The number of list items in these examples is static. However, there are use cases, where the number of items is dynamic. Consider the following example:

i=0;
listData.add(new CustomListItemData("Item A", i++, 20));
listData.add(new CustomListItemData("Item B", i++, 20));
if (x=y) {
  listData.add(new CustomListItemData("Item X", i++, 20));
  listData.add(new CustomListItemData("Item Y", i++, 20));
}
listData.add(new CustomListItemData("Item C", i++, 20));
listData.add(new CustomListItemData("Item D", i  , 20));

In this case, we can set indexInSection for each item by incrementing an integer variable (i++) that starts at 0. However, when starting to populate the above listData array, it's not yet known how many items the final list will contain. It can be either 4 or 6. So, it's unclear to me what numbers have to be added for sectionCount for each item.

Requirement: How should we handle such a use case when using a List with a dynamic number of items (sectionCount)?

[michael-winkler]

Just use an ArrayList. You dont need to the size of the list for ArrayLists.

[patrickfrei]

Hmm, I don't fully understand, I already use an ArrayList for listData. Do you maybe have an example what you mean?

[dsn5ft]

@patrickfrei good question. @imhappi I think if the total item count is not known ahead of time we should probably add methods like:

• listItemLayout.updateAppearance(positionState)
• listItemViewHolder.bind(positionState)

(where positionState, naming TBD, is an enum of FIRST | MIDDLE | LAST | SINGLE)