Lesson 19 - Enumerated types and constants in Kotlin
In the previous lesson, Abstract class, comparing and operators in Kotlin, we went over abstract classes and learned how to compare instances of our own classes. The last 3 lessons were very practical, as in lots of doing and getting right into sample programs. This time around we're going to get back into theoretical concepts for a little bit.
A common thing in software development is having a variable that is only
supposed to contain one of a set of specific values. An example might be an
order status in an e-shop. The order may be new, accepted, approved or
completed. It cannot be in any other state in order to function properly. Other
examples include the days of the week, job positions and so on. With our current
knowledge, we could probably store the order status as a string. Doing so is a
common cause of errors since we wouldn't have a mechanism to check whether the
value is valid. Therefore, Kotlin provides enumerated types
enums). We declare an
enum similarly as a class.
We'll add an
enum to a project as we do it with a class or an
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This lesson is about enumerated types (enums) in Kotlin. We'll also learn to use their contructor and implement constants.
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