ArrayIndexOutOfBoundsException assigning to charArrayOf()

Question

Could someone help me to understand where I've gone wrong because it seems that I keep on getting this error:

java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0

fun main()
{

    arrayOfNulls<String?>(size = 11)
    var firstWord : String?

    print("Enter in the sentence ")
    var strAnagram : String = readLine()!!

    var arrUserInput = strAnagram.split(" ")
    var  arrFirstLetter = charArrayOf()

    for(x in 0..arrUserInput.size+1)
    {
        firstWord = arrUserInput.get(x)
        arrFirstLetter[x] = firstWord[0]

    }

    for (y in 0..11)
    {
    println(arrFirstLetter[y])
    }

}

It looks like you're trying to make acronyms, not anagrams.

DodgyCodeException
– DodgyCodeException

2020-04-27 14:18:23 +00:00
Commented Apr 27, 2020 at 14:18 — DodgyCodeException
– DodgyCodeException, Commented Apr 27, 2020 at 14:18

Adam Millerchip · Accepted Answer · 2020-04-27 14:23:54Z

3

When you write var arrFirstLetter = charArrayOf() you are creating an empty array.

Then when you write arrFirstLetter[x] = firstWord[0], you are trying to assign to the element at index x of an empty array. Because the array is empty, this is generating ArrayIndexOutOfBoundsException.

In general it's better to avoid trying to loop over collections by using their index and instead use a for loop or the map extension function.

You can print out the first letters of each word like this:

fun main() {
    print("Enter in the sentence ")
    val userInputWords: List<String> = readLine()?.split(" ") ?: emptyList()

    for (word in userInputWords) {
        println("First letter: ${word[0]}")
    }
}

answered Apr 27, 2020 at 14:23

Adam Millerchip

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1 Comment

Adam Millerchip Over a year ago

I missed the case where the input contains an empty string. It's more complex, but you can cover that with for (word in userInputWords.filter { it.isNotEmpty() })

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