What is the difference between ListView and SingleChildScrollView ListBody in Flutter?-CodePudding

I have a question about comparing ListView and SingleChildScrollView containing a ListBody. Seemingly, those two results look the same. But I'm curious about whether those two have a difference in function. In my opinion, it could be the part of efficiency or performance, but I'm not sure. Thanks in advance.

SingleChildScrollView ListBody

final items = List.generate(100, (index) => index).toList();

SingleChildScrollView(
  child: ListBody(
    children: items.map((e) => Text('$e')).toList(),
  )
)

ListView

final items = List.generate(100, (index) => index).toList();

ListView(
  children: items.map((e) => Text('$e')).toList(),
)

CodePudding user response：

You could consider ListView as an optimisation to the combination of SingleChildScrollView Column.

By using ListView, only the items that are visible are mounted and painted.

On the other hand, by using SingleChildScrollView Column, the entire item list is mounted painted, even if only a few items are visible.

The tradeoff is that ListView is less flexible. So for complex layouts with a small number of items, the performance gain may not be worth the trouble, in which case we can use SingleChildScrollView.

CodePudding user response：

I must say I actually have never even heard of the widget ListBody, but when you check its source code you can actually see the comment:

/// This widget is rarely used directly. Instead, consider using [ListView],
/// which combines a similar layout algorithm with scrolling behavior, or
/// [Column], which gives you more flexible control over the layout of a
/// vertical set of boxes.

So the flutter devs themselves sort of don't recommend using it. I also don't know what the exact difference is, so I guess I'm not really answering your question. Maybe someone else can, but you also could just investigate the source code yourself, since it's all open source.