What are the uses of enum classes in Kotlin?

An enum class in Kotlin is a class that defines a set of fixed values. Here is how an enum class is used:

1. Define an enum class: In Kotlin, you can define an enum class using the enum keyword. For example:

enum class Color {
    RED, GREEN, BLUE
}

1. Enumerated values can be accessed by using the enum class name and the enum value name. For example:

val color: Color = Color.RED
println(color) // 输出 RED

1. Iterating through enum values: You can use the enumValues() function to retrieve all enum values from an enum class and iterate through them. For example:

for (color in enumValues<Color>()) {
    println(color)
}

1. To obtain the name and order of an enumeration value: you can use the name property to get the name of the value and the ordinal property to get the order of the value. For example:

val color: Color = Color.GREEN
println(color.name) // 输出 GREEN
println(color.ordinal) // 输出 1

1. Customize the properties and methods of enumerated values: You can define properties and methods within the enumerated values. For example:

enum class Color(val rgb: Int) {
    RED(0xFF0000),
    GREEN(0x00FF00),
    BLUE(0x0000FF);

    fun getColorName(): String {
        return name.toLowerCase()
    }
}

val color: Color = Color.RED
println(color.rgb) // 输出 16711680
println(color.getColorName()) // 输出 red

In conclusion, Kotlin enums offer a convenient way to define a set of fixed values and perform operations and iterations on them.