Flutter / Dart Convert Int to Enum

Question

Is there a simple way to convert an integer value to enum? I want to retrieve an integer value from shared preference and convert it to an enum type.

My enum is:

enum ThemeColor { red, gree, blue, orange, pink, white, black };

I want to easily convert an integer to an enum:

final prefs = await SharedPreferences.getInstance();
ThemeColor c = ThemeColor.convert(prefs.getInt('theme_color')); // something like that

How did you add enum in the SharedPrefs. Could you please guide me a bit. — Pawan, Nov 13 '18 at 10:10
@Pawan being `status` an `enum`, you can `status.index` to get the int value — maganap, Jan 19 '20 at 22:54

score 141 · Accepted Answer · answered Jul 05 '18 at 11:22

141

int idx = 2;
print(ThemeColor.values[idx]);

should give you

ThemeColor.blue

answered Jul 05 '18 at 11:22

Günter Zöchbauer

623,577
216
2,003
1,567

score 31 · Answer 2 · edited Oct 23 '20 at 06:44

31

You can use:

ThemeColor.red.index

should give you

edited Oct 23 '20 at 06:44

Zig Razor

3,381
2
15
35

answered Oct 23 '20 at 04:16

Farman Ameer

1,234
2
16
22

score 12 · Answer 3 · answered Apr 19 '22 at 12:03

In Dart 2.17, you can use enhanced enums with values (which could have a different value to your index). Make sure you use the correct one for your needs. You can also define your own getter on your enum.

//returns Foo.one
print(Foo.values.firstWhere((x) => x.value == 1));
  
//returns Foo.two
print(Foo.values[1]);
  
//returns Foo.one
print(Foo.getByValue(1));

enum Foo {
  one(1),
  two(2);

  const Foo(this.value);
  final num value;
  
  static Foo getByValue(num i){
    return Foo.values.firstWhere((x) => x.value == i);
  }
}

score 2 · Answer 4 · answered Jun 29 '22 at 08:54

Warning, make sure you handle non-existent integer with a try/catch.

/// Shows what to do when creating an enum value from a integer value

enum ThemeColor { red, green,}


void main() {
  
  try {
    final nonExistent = ThemeColor.values[3];
    print("Non existent enum is $nonExistent");

  }
  catch(e) {
    print("Non existent enum thrown"); 
  }
}

// Non existent enum thrown

The dartpad: https://dartpad.dev/?id=4e99d3f578311288842a0ab5e069797e

Giorgio Barchiesi · Answer 5 · 2023-09-02T06:05:06.903

Another solution with enhanced enums, plus:

More propertie(s) attached to enum values
Factory constructor
Fallback value in constructor
Implementation of the Comparable interface
Overload of comparison operator(s)
Conversion to map

Tested on Dart 2.19.6.

enum AuthLevel implements Comparable<AuthLevel> {
  guest(1, 'Guest'),
  user(2, 'Registered user'),
  admin(5, 'Administrator'),
  developer(9, 'Developer');

  final int level;
  final String desc;

  const AuthLevel(this.level, this.desc);

  // Conversion from int
  factory AuthLevel.fromInt(int level) =>
      values.firstWhere((value) => value.level == level, orElse: () => guest);

  // Conversion to int
  int get toInt => level;

  @override
  int compareTo(AuthLevel other) => level - other.level;

  // Comparison operator(s)
  bool operator >=(AuthLevel other) => level >= other.level;
  // ... possibly add more

  @override
  String toString() => '{level: $level, desc: $desc}';

  // Conversion to map
  Map<int, String> toMap() =>
      {for (var value in AuthLevel.values) value.level: value.desc};
}

Flutter / Dart Convert Int to Enum

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