How much performance impact `copy` function of `da...

# android

[Kulwinder Singh]

How much performance impact copy function of data class have if called many times ??

for example i have data class Position(val x:Float,val y:Float) and i'm doing copy of this class's instance inside android's touch listener when user's finger is moved(ACTION_MOVE) like ->

var position = Position(0f, 0f)
view.setOnTouchListener { v, event ->
    when (event.action){
        MotionEvent.ACTION_DOWN -> /**/
        MotionEvent.ACTION_MOVE -> {
            position = position.copy(x =computedX,y=computedY)//how much performance impact of this ??
        }
    }

}

i don't want to use mutable properties for data class for some reasons

[gildor]

essentailly the same as Position(computedX, computedY), it creates an object

[gildor]

also not sure why you need copy here, you modify all the available properties, nothing to copy, it’s the same as create a new one

[gildor]

mutable will be better of course, less pressure on GC

[gildor]

but if it doesn’t cause any problems on practice it would be fine

[Kulwinder Singh]

I don't want to make properties mutable in real app because i want to update properties at specific place

[gildor]

so what kind choice you have? 🙂

[gildor]

or be a bit more optimized and mutable, or immutable and create an object on every touch event

[gildor]

on practice you will not notice any slowdown, it’s not onDraw after all

[Kulwinder Singh]

so what kind choice you have?

only copy 😉, but i was curious to know how much its going to effect

[gildor]

method call, object cretion, nothing magical there

[gildor]

only copy

Actuallyu in case of Position you even don’t need copy, probably call of constructor would be more explicit

[Kulwinder Singh]

you are right, but in real app i have more properties in Position 🙂

[Kulwinder Singh]

No issues, thank you for help

[gildor]

@NotNull
public final Position copy(int x, int y) {
   return new Position(x, y);
}

[gildor]

decompiled copy method

[Kulwinder Singh]

got it,
BTW when will be those previously(unwanted) created Position objects collected by GC ?

[gildor]

depends on GC, different Android GCs has a bit different strategies

[gildor]

If you curious, recommend to check this talk

https://www.youtube.com/watch?v=oKMsPrDMprE▾

It gives some introduction on different GCs

[Kulwinder Singh]

yeah sure, i will definitely check it

[Ryan]

make ur own data class with mutable properties, when done use the non mutable. seems like what your trying to do is the root of all evil