I caught the following errors when adding a new pair to a Map.
Variables must be declared using the keywords const, final, var, or a type name
Expected to find;
the name someMap is already defined
I executed the following code.
Map<String, int> someMap = {
"a": 1,
"b": 2,
};
someMap["c"] = 3;
How should I add a new pair to the Map?
I'd also like to know how to use Map.update
.
To declare your map in Flutter you probably want final
:
final Map<String, int> someMap = {
"a": 1,
"b": 2,
};
Then, your update should work:
someMap["c"] = 3;
Finally, the update
function has two parameters you need to pass, the first is the key, and the second is a function that itself is given one parameter (the existing value). Example:
someMap.update("a", (value) => value + 100);
If you print the map after all of this you would get:
{a: 101, b: 2, c: 3}