How to fill String[] array in Kotlin

Question

I have a method in java just like this and I want to convert it to kotlin. I wrote a method in kotlin but array does not fill and I have null array in return. how can I fix that? Thank in Advance.

Java code

private String[] getNameOfPersonalityTpye(List<PersonalityTpye> list){
        String[] s = new String[list.size()];
        for(int i = 0; i < list.size(); i++){
            s[i] = list.get(i).getPersonalityTypeName();
        }
        return s;
    }

Kotlin code

private fun getNameOfPersonalityTpye(list: List<PersonalityTpye>): Array<String?>{
        val s=  arrayOfNulls<String>(list.size);
        for(i in list.indices){
            s[i] = list[i].name;
        }
        return s;
    }

Try printing list[i].name in console, do you see anything? — Daksh Gargas
– Daksh Gargas, Commented Dec 12, 2018 at 8:44
@Dennis Yeah, I can see all 4 items in list when I debug it. I'm steel wondering why s array does not fill just like java method — Mohsen Hatami
– Mohsen Hatami, Commented Dec 12, 2018 at 8:47
I mean did you explicitly println(list[i].name) ? I mean what if it's returning a null value? — Daksh Gargas
– Daksh Gargas, Commented Dec 12, 2018 at 8:50

forpas · Accepted Answer · 2018-12-12 10:16:20Z

4

With map and toTypedArray():

private fun getNameOfPersonalityType(list: List<PersonalityType>) = list.map { it.name }.toTypedArray()

I guess it's Type and not Tpye
Just check the size after. If it is 0 then the list was empty.
If the list passed as parameter may contain null values, then change to this:

private fun getNameOfPersonalityType(list: List<PersonalityType?>) = list.mapNotNull { it?.name }.toTypedArray()

edited Dec 12, 2018 at 10:16

answered Dec 12, 2018 at 8:37

forpas

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Comments

theanilpaudel · Accepted Answer · 2018-12-12 08:49:25Z

2

This is working perfectly fine

private fun check(){
        val list = ArrayList<String>()
        list.add("json")
        list.add("statham")
        println("value from array "+getNameOfPersonalityTpye(list)[1]) //prints statham
    }

    private fun getNameOfPersonalityTpye(list:List<String>): Array<String?>{
        val s=  arrayOfNulls<String>(list.size)
        for(i in s.indices){
            s[i] = list[i]
        }
        return s
    }

So this list[i].name; in your code might be null. Otherwise everything is fine.

answered Dec 12, 2018 at 8:49

theanilpaudel

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Comments

SamHoque · Accepted Answer · 2018-12-12 09:04:40Z

0

You can do the following with Stream

private fun getNameOfPersonalityTpye(list: List<PersonalityTpye>): Array<String> {
    return list.stream().map<Any> { e -> e.getPersonalityTypeName() }.toArray() as Array<String>
}

answered Dec 12, 2018 at 9:04

SamHoque

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