I was hoping that a null-checking filter on a coll...

# getting-started

[v79]

I was hoping that a null-checking filter on a collection would safely return only the non-null elements, that I could then check for other values. Unfortunately, intelliJ/compiler not accepting this: `

hexes.filter { it.hexData != null }
    .first { it.hexData.row == newHexData.row && it.hexData.column == newHexData.column }

Any suggestions? Ideally without creating a new list of hexes?

[Joffrey]

In this case you can simply move the null check into the first lambda, and ditch the filter

[Joffrey]

It's also more efficient this way because you don't create an intermediate collection

[v79]

Like this?

hexes.first { it.hexData != null && it.hexData.row == newHexData.row && it.hexData.column == newHexData.column }

[v79]

I've still got nullables to deal with because it's a "mutable property that could have been changed by this time". It won't have been, so that's more !! for me to add 😞 It's for a game written with Godot, so there are loads of !! already.

[Youssef Shoaib [MOD]]

hexes.mapNotNull { it.hexData }.first { it.row == newHexData.row && it.column == newHexData.column }

[Daniel Pitts]

That's assuming they only want hexData, not the entire outer object.

[Daniel Pitts]

hexes.first {
   it.hexData?.run { row == newHJexData.row && column = newHexData.column } == true
}

[v79]

Hmm! I do need the outer object. I use ?.let often enough, tend to forget about run.

[Daniel Pitts]

you could also use ?.let, but it outside would be different than it inside, and that's just ugly 😉

[Daniel Pitts]

Either way, I would consider extracting that into a function in HexData

class HexData(...) {
   fun isSameCellAs(other: HexData):Boolean { ... }
}

Then : hexes.first { it.hexData?.isSameCellAs(newHexData) }