map_entry_not_in_map

Map entries can only be used in a map literal.

The analyzer produces this diagnostic when a map entry (a key/value pair) is found in a set literal.

The following code produces this diagnostic because the literal has a map entry even though it's a set literal:

var collection = <String>{'a' : 'b'};

If you intended for the collection to be a map, then change the code so that it is a map. In the previous example, you could do this by adding another type argument:

var collection = <String, String>{'a' : 'b'};

In other cases, you might need to change the explicit type from Set to Map.

If you intended for the collection to be a set, then remove the map entry, possibly by replacing the colon with a comma if both values should be included in the set:

var collection = <String>{'a', 'b'};

Unless stated otherwise, the documentation on this site reflects Dart 3.8.0. Page last updated on 2025-05-08. View source or report an issue.