What is the best way to compare two classes of the same type, and copy all the properties of the second one that are different compared to an original? For example, let's say I have 3 string variables stored in said class:

class SomeClass {
    var string1: String = "Default"
    var string2: String = "Default"
    var string3: String = "Default"
}

and lets say in the first class,

string1

is "Text,"

string2

, is "Other Text," and in the second class

string1

is "String, " while

string2

is still Default I would want it so that the first string is "String," the second string is "Other Text," and

string3

as "Default"

when you say "first class" and "second class", you mean "first instance of SomeClass", and "second instance of SomeClass"? Or do you want to compare 3 different classes? Why do you expect

string2="Other Text"

? Shouldn't it be "Default", because

second.string1 != first.string1

?

Yes, I'm referring them as all the same class, but with different properties

putting a "default" value on a string means it has a special meaning within your code. I think it might be better to just use

String?

instead, but regardless. I dont know what you want with the copying over, but you can do:

import SomeClass.Companion.DEFAULT

class SomeClass {
    companion object {
        const val DEFAULT = "Default"
    }
    var string1: String = DEFAULT
    var string2: String = DEFAULT
    var string3: String = DEFAULT
}

fun main() {
    val class1 = SomeClass().apply {
        string1 = "Text"
        string2 = "OtherText"
    }
    val class2 = SomeClass().apply {
        string1 = "String"
    }

    val result1 = class2.string1.takeUnless(DEFAULT::equals) ?: class1.string1
    val result2 = class2.string2.takeUnless(DEFAULT::equals) ?: class1.string2
    val result3 = class2.string3.takeUnless(DEFAULT::equals) ?: class1.string3

    println(result1)
    println(result2)
    println(result3)
}

this prints, in order:

String
OtherText
Default

if you instead have nullable string with null being the default, you can just do:

val result1 = class2.string1 ?: class1.string1
    val result2 = class2.string2 ?: class1.string2
    val result3 = class2.string3 ?: class1.string3

Alright, thanks!