How to use less than < or greater > than in kotlin

Question

How to use less than (<) or greater than (>) operator in kotlin?

I have checked comparedTo(other: Int?) function, but it only returns Int?.

class Adapter{
     private var mNewsCategories: List<NewsCategory>? = null
     //......
     val isAnything=  this.mNewsCategories?.size?.compareTo(0))
     //......
 }

The val isAnything returns another Int?. Actually, I need a Boolean variable.

Thanks in advance

@OliverCharlesworth Don't know, but I wonder how adding `> 0` would work semantically with `null` values, since that's how I understood your suggestion. — Marko Topolnik, Feb 18 '18 at 12:11
@OliverCharlesworth If it is `Int?` then there is a possibility of null, so we can't use `< or >` directly — noobEinstien, Feb 18 '18 at 12:17

s1m0nw1 · Accepted Answer · 2018-02-18T20:56:34.343

9

It’s not possible to use > on nullable types. If you consider null to map to the size 0, i.e. empty size, you can do:

val isAnything = (this.mNewsCategories?.size? ?: 0) > 0

While this will fix your problem, you should consider using isNotEmpty instead:

val isAnything = this.mNewsCategories?.isNotEmpty() ?: false

The Elvis Operator is explained here.

edited Feb 18 '18 at 20:56

answered Feb 18 '18 at 12:01

s1m0nw1

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Thanks for the precious answer. Can you explain elvis operator do, it will help lot of others . – noobEinstien Feb 18 '18 at 12:22
See this one https://stackoverflow.com/a/48254829/8073652 – s1m0nw1 Feb 18 '18 at 12:24
2

Though, when checking for empty lists using `isNotEmpty` is probably easier than comparing to 0 – Zoe Feb 18 '18 at 12:36
That's probably true – s1m0nw1 Feb 18 '18 at 19:49

How to use less than < or greater > than in kotlin

1 Answers1