How can I compare Lists for equality in Dart?

To complete Gunter's answer: the recommended way to compare lists for equality (rather than identity) is by using the Equality classes from the following package

import 'package:collection/collection.dart';

Edit: prior to 1.13, it was import 'package:collection/equality.dart';

E.g.:

Function eq = const ListEquality().equals;
print(eq([1,'two',3], [1,'two',3])); // => true

The above prints true because the corresponding list elements that are identical(). If you want to (deeply) compare lists that might contain other collections then instead use:

Function deepEq = const DeepCollectionEquality().equals;
List list1 = [1, ['a',[]], 3];
List list2 = [1, ['a',[]], 3];
print(    eq(list1, list2)); // => false
print(deepEq(list1, list2)); // => true

There are other Equality classes that can be combined in many ways, including equality for Maps. You can even perform an unordered (deep) comparison of collections:

Function unOrdDeepEq = const DeepCollectionEquality.unordered().equals;
List list3 = [3, [[],'a'], 1];
print(unOrdDeepEq(list2, list3)); // => true

For details see the package API documentation. As usual, to use such a package you must list it in your pubspec.yaml:

dependencies:
  collection: any

For those using Flutter, it has the native function listEquals, which compares for deep equality.

import 'package:flutter/foundation.dart';

var list1 = <int>[1, 2, 3];
var list2 = <int>[1, 2, 3];

assert(listEquals(list1, list2) == true);

import 'package:flutter/foundation.dart';

var list1 = <int>[1, 2, 3];
var list2 = <int>[3, 2, 1];

assert(listEquals(list1, list2) == false);

Note that, according to the documentation:

The term "deep" above refers to the first level of equality: if the elements are maps, lists, sets, or other collections/composite objects, then the values of those elements are not compared element by element unless their equality operators (Object.operator==) do so.

Therefore, if you're looking for limitless-level equality, check out DeepCollectionEquality, as suggested by Patrice Chalin.

Also, there's setEquals and mapEquals if you need such feature for different collections.

Collections in Dart have no inherent equality. Two sets are not equal, even if they contain exactly the same objects as elements.

The collection library provides methods to define such an equality. In this case, for example

IterableEquality().equals([1,2,3],[1,2,3])

is an equality that considers two lists equal exactly if they contain identical elements.