I'll have to lookup the definition of

readResolve

but from my cursory knowledge, that sounds like it might work.

Any way to efficiently get key from value in Kotlin?

in some Map kind of datastructure

It is available in java 8 streams, but have to support devices below api level 24 as well

@feroz_baig Does BidiMap work for you? http://commons.apache.org/proper/commons-collections/apidocs/org/apache/commons/collections4/BidiMap.html

Otherwise

map.entrySet().find{ it.value == myValue }

@feroz_baig The best way is to maintain the reverse map yourself. Create your own wrapper for that (no need to pull the whole Apache collections)

tyrus or jetty perhaps?

why doesn’t the type information make it through to the lazy initializer:

val templateService: TemplateService by lazy { config.instance () }

@lee.crawford uploaded a file:

not an answer but actually what you want: https://salomonbrys.github.io/Kodein/#_via_lazy_properties

val templateService: TemplateService by config.lazy.instance()

@lee.crawford there is an issue about that somewhere on https://youtrack.jetbrains.com

so basically its possible, but it hasn't been implemented yet

Hello, is there any function in the kotlin standard library I can use for verifying data hasn't changed? Something like a checksum or a quick hashing function?

hashCode

on a data class?

It's a json string. I suppose I can cast it to a data object then get the hashCode, but that seems like an unneeded extra step?

Or am I overlooking something obvious here?

String already has a hashcode implemetation, just use that.

Oh, nice. So, the json is stored in a database. I can retrieve it from the DB, assign it to a string, and then call .hashCode and it should be the same if the string hadn't changed?

(Now that I write this I realise I'm probably approaching this wrong and I should just have a timestamp in the DB for last modified... but still curious about my original question)

Yes, hashCode will return the same value for the same strings.

Okay, great. Thank you! I think I'll approach this with a timestamp, but it's still useful information to know. Thank you very much 🙂

Do note that hash collisions exist, different strings can have the same hash.

I was basically just looking to optimise my api a bit and not return all the data if it hasn't changed since the last time a client had polled. I'll take that into account 😃 As I said, most likely will just use a timestamp.

Cheers, Karel! Thanks man 😃 You're always helping everyone, it's pretty cool to see.

Agreed, but it looks like he recognized that himself already.

"Most likely" isn't good enough for me 🙂 I better explain. if two strings' hashCodes are different that definitely means that these strings are not equal, but if hashCodes match that doesn't mean that strings are equal. The probability of clashes for standard hashCode is quite high. Look at this small illustration for example: https://dzone.com/articles/what-is-wrong-with-hashcode-in-javalangstring

The name is a click bate of course, nothing is wrong with

hashCode

it is just not intended as a stand-alone equality checking tool