Why does the following code return true for Float ...

# kotlin-native

[Matej Kormuth]

Why does the following code return true for Float comparison and false in some cases for objects?

data class B(val a: Float, val b: Float)

data class A(val a: Float, val b: Float) {
    override fun equals(other: Any?): Boolean {
        if(other is A) {
            return a == other.a && b == other.b
        }
        return false
    }
}

fun main(args: Array<String>) {
    println(0.0f == -0.0f) // true
    println(B(0.0f, 0.0f) == B(0.0f, -0.0f)) // false
    println(B(2f, 4f) == B(2f, 4f)) // true
    println(A(0.0f, 0.0f) == A(0.0f, -0.0f)) // true (workaround)
}

[Matej Kormuth]

This look like a bug for me as the generated equals() for the data class is returning false for comparison that otherwise returns (and should return) true.

[Matej Kormuth]

Also I am using id 'kotlin-multiplatform' version '1.3.11'

[olonho]

This is intentional behavior, and matches one on JVM, see equals section in https://docs.oracle.com/javase/7/docs/api/java/lang/Float.html

[Matej Kormuth]

So are the a, b properties represented as boxed types and not primitives? Or the `equals`and hashCode are implemented in a way that even non-boxed types are considered as "boxed" during to comparison?

[olonho]

nope, just members compared with equals, for example println(0.0f.equals(-0.0f)) prints false

[uli]

Why does the workaround return true then?

[olonho]

Because it overrides comparison

[uli]

But it uses float comparison under the hood, right?

[uli]

And you say println(0.0f.equals(-0.0f)) prints false

[olonho]

equals and == is not the same operation for floats

[uli]

Got it. Thanks