Stage 1 · Lesson 6 of 10
List, Map and Set
Most screens show a List, look things up in a Map and track selections in a Set. Learn how to write each one directly: [1, 2], {'a': 1} and {1, 2}. Then learn the operations: map, where, fold, any, firstWhere, sort and toList.
Note that map and where return a lazy Iterable, a sequence that is only worked out when read. So you often add .toList() before passing the result to a . Collection if and for let you build lists inline, as in [if (isAdmin) adminTile, for (final p in posts) PostTile(p)]. You will use that constantly in .
Common trapsorting or adding to a list in place and expecting the UI to notice; create a new list instead.
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Resources for this stage
Start with
- GuideFreeDart Language Tour
Google · Beginner
The official tour: read it in order and rerun every example in DartPad