Kotlin: Maps comparison throws Fail even if Maps are equal - kotlin

Question

I'm trying to compare 2 Maps, both are filled with identical Strings (just for training).
When I try to compare them I got false returned through map.equals(map2)
But if I do the same and add .toString() to the comparison it returns true. map.toString().equals(map2.toString())
How's that? What am I doing wrong?
Also happens the same with Kluent library and its shouldEqual method.
I also tried to get values of that maps into arrays and tried to compare that arrays but it still returns false.
Also, when I print all items from each map I see the same 3 Strings but comparison returns fail.
Here's the code:
class MapsTesting {
class Items(name1: String, amount1: String, price1: String) {
var name: String = name1
var amount: String = amount1
var price: String = price1
override fun toString(): String {
return "name:$name,amount:$amount,price:$price \n"
}
}
#Test
fun mapTest() {
val mapOfItems: MutableMap<String, Items> = mutableMapOf()
mapOfItems["Materials"] = Items("STEP 1", "STEP 2", "View All Stones")
val mapOfItems2: MutableMap<String, Items> = mutableMapOf()
mapOfItems2["Materials"] = Items("STEP 1", "STEP 2", "View All Stones")
mapOfItems.forEach { t, u ->
println("map key:$t,map value:${u.toString()}")
}
mapOfItems2.forEach { t, u ->
println("map key:$t,map value:${u.toString()}")
}
val comparison : Boolean = mapOfItems.toString().equals(mapOfItems2.toString())
//this returns true
val comparison2 : Boolean = mapOfItems.equals(mapOfItems2)
//this returns false
println(comparison)
println(comparison2)
val map1 = mapOfItems.toString()
val map2 = mapOfItems2.toString()
//this returns true
//if I delete toString() it will return false
map1 shouldEqual map2
}
}
Here's the error I got:
java.lang.AssertionError: expected: java.util.LinkedHashMap<{Materials=name:STEP 1,amount:STEP 2,price:View All Stones
}> but was: java.util.LinkedHashMap<{Materials=name:STEP 1,amount:STEP 2,price:View All Stones
}>

Answer 1

When comparing two maps with the equals method, the standard implementation compares all keys and values also using the equals method.
Your Items class uses the standard equals implementation (two reference values are equal if and only if they refer to the same object). But you clearly have two different instances of the in different maps.
You either have to override the Items#equals method or mark the Items class as a data class:
data class Items(var name1: String, var amount1: String, var price1: String)
Kotlin will generate correct equals, hashCode and toString methods.
After this the map comparison will work fine.