Create Array without nullable types from Array with nullable types











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In Kotlin we have to distinguish between nullable types and not nullable types. Let's say I have an Array<String?> fom which I know that every value within it is actually not null. Is there an easy way to create an Array<String> from the source array without copying it?






kotlin kotlin-null-safety







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  • How about mapNotNull().toArray()?
    – EpicPandaForce
    Nov 21 at 12:32















up vote
0
down vote

favorite












In Kotlin we have to distinguish between nullable types and not nullable types. Let's say I have an Array<String?> fom which I know that every value within it is actually not null. Is there an easy way to create an Array<String> from the source array without copying it?






kotlin kotlin-null-safety







share|improve this question






















  • How about mapNotNull().toArray()?
    – EpicPandaForce
    Nov 21 at 12:32













up vote
0
down vote

favorite









up vote
0
down vote

favorite











In Kotlin we have to distinguish between nullable types and not nullable types. Let's say I have an Array<String?> fom which I know that every value within it is actually not null. Is there an easy way to create an Array<String> from the source array without copying it?






kotlin kotlin-null-safety







share|improve this question













In Kotlin we have to distinguish between nullable types and not nullable types. Let's say I have an Array<String?> fom which I know that every value within it is actually not null. Is there an easy way to create an Array<String> from the source array without copying it?






kotlin kotlin-null-safety




kotlin kotlin-null-safety






share|improve this question













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share|improve this question




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asked Nov 21 at 12:29









Cilenco

2,595948100




2,595948100












  • How about mapNotNull().toArray()?
    – EpicPandaForce
    Nov 21 at 12:32


















  • How about mapNotNull().toArray()?
    – EpicPandaForce
    Nov 21 at 12:32
















How about mapNotNull().toArray()?
– EpicPandaForce
Nov 21 at 12:32




How about mapNotNull().toArray()?
– EpicPandaForce
Nov 21 at 12:32












2 Answers
2






active

oldest

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up vote
3
down vote



accepted










array.requireNoNulls() returns same array Array<T?> with non-optional type Array<T> (But throws IllegalArgmentException if any of the item found null).



if you are sure that your array doesn't have null then you can typecast.



array as Array<String>






share|improve this answer























  • array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
    – forpas
    Nov 21 at 14:04










  • @forpas Good catch. I have updated the answer. Thanks!
    – I Don't Exist
    Nov 21 at 14:08


















up vote
0
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Array.filterNotNull might be the safer way to do it. But it will create a new Array.



val items: Array<String?> = arrayOf("one", "two", null, "three")

val itemsWithoutNull: List<String> = items.filterNotNull()





share|improve this answer























  • question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
    – I Don't Exist
    Nov 21 at 13:11










  • Good point. I mentioned this.
    – Michi Gysel
    Nov 21 at 14:00











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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
3
down vote



accepted










array.requireNoNulls() returns same array Array<T?> with non-optional type Array<T> (But throws IllegalArgmentException if any of the item found null).



if you are sure that your array doesn't have null then you can typecast.



array as Array<String>






share|improve this answer























  • array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
    – forpas
    Nov 21 at 14:04










  • @forpas Good catch. I have updated the answer. Thanks!
    – I Don't Exist
    Nov 21 at 14:08















up vote
3
down vote



accepted










array.requireNoNulls() returns same array Array<T?> with non-optional type Array<T> (But throws IllegalArgmentException if any of the item found null).



if you are sure that your array doesn't have null then you can typecast.



array as Array<String>






share|improve this answer























  • array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
    – forpas
    Nov 21 at 14:04










  • @forpas Good catch. I have updated the answer. Thanks!
    – I Don't Exist
    Nov 21 at 14:08













up vote
3
down vote



accepted







up vote
3
down vote



accepted






array.requireNoNulls() returns same array Array<T?> with non-optional type Array<T> (But throws IllegalArgmentException if any of the item found null).



if you are sure that your array doesn't have null then you can typecast.



array as Array<String>






share|improve this answer














array.requireNoNulls() returns same array Array<T?> with non-optional type Array<T> (But throws IllegalArgmentException if any of the item found null).



if you are sure that your array doesn't have null then you can typecast.



array as Array<String>







share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 21 at 14:07

























answered Nov 21 at 12:37









I Don't Exist

2,32511418




2,32511418












  • array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
    – forpas
    Nov 21 at 14:04










  • @forpas Good catch. I have updated the answer. Thanks!
    – I Don't Exist
    Nov 21 at 14:08


















  • array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
    – forpas
    Nov 21 at 14:04










  • @forpas Good catch. I have updated the answer. Thanks!
    – I Don't Exist
    Nov 21 at 14:08
















array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
– forpas
Nov 21 at 14:04




array.requireNoNulls() is safer to use in what sense? It throws an IllegalArgumentException if there are any null elements.
– forpas
Nov 21 at 14:04












@forpas Good catch. I have updated the answer. Thanks!
– I Don't Exist
Nov 21 at 14:08




@forpas Good catch. I have updated the answer. Thanks!
– I Don't Exist
Nov 21 at 14:08












up vote
0
down vote













Array.filterNotNull might be the safer way to do it. But it will create a new Array.



val items: Array<String?> = arrayOf("one", "two", null, "three")

val itemsWithoutNull: List<String> = items.filterNotNull()





share|improve this answer























  • question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
    – I Don't Exist
    Nov 21 at 13:11










  • Good point. I mentioned this.
    – Michi Gysel
    Nov 21 at 14:00















up vote
0
down vote













Array.filterNotNull might be the safer way to do it. But it will create a new Array.



val items: Array<String?> = arrayOf("one", "two", null, "three")

val itemsWithoutNull: List<String> = items.filterNotNull()





share|improve this answer























  • question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
    – I Don't Exist
    Nov 21 at 13:11










  • Good point. I mentioned this.
    – Michi Gysel
    Nov 21 at 14:00













up vote
0
down vote










up vote
0
down vote









Array.filterNotNull might be the safer way to do it. But it will create a new Array.



val items: Array<String?> = arrayOf("one", "two", null, "three")

val itemsWithoutNull: List<String> = items.filterNotNull()





share|improve this answer














Array.filterNotNull might be the safer way to do it. But it will create a new Array.



val items: Array<String?> = arrayOf("one", "two", null, "three")

val itemsWithoutNull: List<String> = items.filterNotNull()






share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 21 at 14:00

























answered Nov 21 at 12:40









Michi Gysel

57149




57149












  • question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
    – I Don't Exist
    Nov 21 at 13:11










  • Good point. I mentioned this.
    – Michi Gysel
    Nov 21 at 14:00


















  • question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
    – I Don't Exist
    Nov 21 at 13:11










  • Good point. I mentioned this.
    – Michi Gysel
    Nov 21 at 14:00
















question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
– I Don't Exist
Nov 21 at 13:11




question says without copying it. filterNotNull creates new ArrayList and adds Non-Null values to that before returning it.
– I Don't Exist
Nov 21 at 13:11












Good point. I mentioned this.
– Michi Gysel
Nov 21 at 14:00




Good point. I mentioned this.
– Michi Gysel
Nov 21 at 14:00


















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