Data classes

data_class_example.kt

package data_classes

data class Machine(val name: String)

enum class ShipType {
    CRUISE,
    WAR,
    GOODS
}

data class Ship(val type: ShipType = ShipType.CRUISE) {
    var safetyBoats = 0
}

data class User(val name: String = "Virat", val age: Int = 35, val nationality: String = "India")

fun main() {
    val machine1 = Machine("Fan")
    val machine2 = Machine("Fan")

    println(machine1) // prints readable format of class instance of object address
    //structural equality check
    println(machine1 == machine2) // true - content equality check
    //referential equality check
    println(machine1 === machine2) // false object address equality check


    val ship1 = Ship()
    ship1.safetyBoats = 4
    val ship2 = Ship()
    ship2.safetyBoats = 2

    println(ship1) // only ship type is printed, safetyBoats count will not be printed since it is inside the body
    println(ship1 == ship2) // should be false but print true. equality check is not performed for member properties
    println(ship1 === ship2)

    // Destructuring declarations

    val (name, age, nationality) = User()
    println("$name, $age, $nationality")
    val (_, _, n) = User()
    println(n)
    val user = User(name = "Dhoni", age = 40)
    println("${user.component1()}, ${user.component2()}, ${user.component3()}")
}