3.2 ListView Performance

Performance with ListView

With a list view, as a cell is “pushed” off the screen due to scrolling, that cell or View object is moved into a Recycler (not to be confused with RecyclerView) and the same View object is reused by the system.

Diagram of how cells are recycled

If we look at the diagram above, when Item 1 is pushed offscreen, it is saved in the Recycler and the View object is reused for Item 8. This can lead to all sorts of bugs.

Let’s say, for example, that every item had a checkbox. If the checkbox in Item 1 is checked, when the Item 1's cell is reused, we’ll see that Item 8 is created with the checkbox already checked. The text in Item 8 has changed, but the View object itself has been reused. This is because the View objects in a list view are not attached to a certain position or item in the list.