code

data class Person(
    val name:String,
    val family:String,
    val age:Int,
    val nationalCode: String?,
    val email: String?,
    val phoneNumber: String?
) {

    // Private constructor
    private constructor(builder: Builder) : this (
        builder.name,
        builder.family,
        builder.age,
        builder.nationalCode,
        builder.email,
        builder.phoneNumber
    )

    // Builder class

    // 1 Necessary parameters in Builder class : name , family
    class Builder(val name :String,val family :String) {

        // 2 Optional parameters in Builder class :
        var age: Int = 0
            private set
        var nationalCode: String? = null
            private set
        var email: String? = null
            private set
        var phoneNumber: String? = null
            private set

        fun age(age: Int) = apply { this.age = age }
        fun nationalCode(nationalCode: String) =
            apply { this.nationalCode = nationalCode }
        fun email(email: String) = apply { this.email = email }
        fun phoneNumber(phoneNumber: String) =
            apply { this.phoneNumber = phoneNumber }

        // 3 Create
        fun create() = Person(this)

    }
}

use

val firstPerson = Person.Builder(
    name = "Adnan",
    family = "Abdollah Zaki")
    .age(32)
    .email("Adnan9011@gmail.com")
    .phoneNumber("+989333030XXX")
    .nationalCode("04400XXXXX")
    .create()

val secondPerson = Person.Builder(
    name = "Foroogh",
    family = "Varmazyar")
    .create()

参考

• How to implement Builder pattern in Kotlin?