How to Sort Keys in a Map in Dart

In Dart, if you want to sort the keys of a Map, you can extract the keys into a list, sort the list, and then reconstruct a new Map based on the sorted key list. Here is a step-by-step guide with an example code:

Extract Keys and Sort: Extract all keys into a list and sort it using the List.sort method.

Reconstruct the Map Based on Sorted Keys: Create a new Map and populate it with values from the original Map based on the sorted key list.

Here is a concrete example:

dart
void main() {
  Map<String, int> unsortedMap = {
    'banana': 3,
    'apple': 1,
    'orange': 2
  };

  // Extract keys into a list
  var keys = unsortedMap.keys.toList();

  // Sort the key list
  keys.sort();

  // Create a new Map and populate it based on the sorted key list
  Map<String, int> sortedMap = { for (var key in keys) key: unsortedMap[key] };

  print(sortedMap); // Output: {apple: 1, banana: 3, orange: 2}
}

This approach is suitable for scenarios requiring lexicographical or custom sorting of keys. For other types of sorting (e.g., numerical order), you can provide a custom comparison function in the sort method.