Ternary operator inside loop generated 'ListView'

You want to add Divider after three and six, But using ternary operator, you are replacing the ListTile widget with Divider.

val? true:false, means here only one will be return. What you need to just check the index and add divider only after three and six, if statement is perfect for this as @Josteve mentioned on his answer. While in children can only be widget instead of list, he is using Column to merge Divider and ListTile, you can use spread operator instead.

ListView(
  children: [
    for (int i = 0; i < 8; i++) ...[
      ListTile(title: Text(items[i])),
      if (i == 2 || i == 5) const Divider()
    ]
  ],
),

You can check more about spread-operator and use cases.

Try this:

for (int i = 0; i < 8; i++) ...[
    ListTile(title: Text(items[i])),
    if (i == 2 || i == 5) const Divider()
]