Enumeration in dart :
Enumeration is an user defined list of constants values. This is a class and also known as enums or enumerated types. Enums are normally used in switch-case blocks. If you are familiar with enums in any other programming languages like Java, enums in Dart is similar to that.
In this post, I will show you how to define enums in dart with examples.
Definition :
Keyword enum is used to define an enumeration. It is defined as like below :
enum EnumName{ list of enums }
EnumName.{name} is used to access one enum value. The below examples will make it more clear.
Accessing index and values :
Each enum values has an index starting from 0. The first value has index 0, second has index 1 etc. We can use the getter property index to access get this position.
Dart also provides one values constant property to get a list of all values of that enum.
Let’s consider the below program :
enum WeekDays { SUN, MON, TUES, WED, THURS, FRI, SAT }
void main() {
print('Index of ${WeekDays.SUN} : ${WeekDays.SUN.index}');
print('Index of ${WeekDays.MON} : ${WeekDays.MON.index}');
print('Index of ${WeekDays.TUES} : ${WeekDays.TUES.index}');
print('Index of ${WeekDays.WED} : ${WeekDays.WED.index}');
print('Index of ${WeekDays.THURS} : ${WeekDays.THURS.index}');
print('Index of ${WeekDays.FRI} : ${WeekDays.FRI.index}');
print('Index of ${WeekDays.SAT} : ${WeekDays.SAT.index}');
print('Values ${WeekDays.values}');
}
It will print the below output :
Index of WeekDays.SUN : 0
Index of WeekDays.MON : 1
Index of WeekDays.TUES : 2
Index of WeekDays.WED : 3
Index of WeekDays.THURS : 4
Index of WeekDays.FRI : 5
Index of WeekDays.SAT : 6
Values [WeekDays.SUN, WeekDays.MON, WeekDays.TUES, WeekDays.WED, WeekDays.THURS, WeekDays.FRI, WeekDays.SAT]
values returns one list. So, we can use one list variable to store these values.
Enums with switch case :
enums are mostly used in switch case statements. For example :
enum Values { ONE, TWO, THREE }
void main() {
var currentValue = Values.THREE;
switch (currentValue) {
case Values.ONE:
print("One");
break;
case Values.TWO:
print("Two");
break;
case Values.THREE:
print("Three");
break;
}
}
It will print the value based on the currentValue. Note that we need to handle all enum’s value if we don’t use default case. It will show one compile time error.
