I was trying to create a recursive function to delete a node of a Binary Search Tree using Kotlin language. During the same I encountered this compile time error saying "Val cannot be reassigned.". I see from similar questions here that parameters of Kotlin are final, that is, they are 'val' and not 'var' in the language of Kotlin. However I want to know if there is still a way to achieve this and be able to assign values to it. I am sharing the code and commenting the ahead of the line where this error is happening.
import kotlin.properties.ReadWriteProperty
import kotlin.reflect.KMutableProperty0
data class Node(var value:Int?){
var data:Int? = value
var left:Node? = null
var right:Node? = null
}
fun insert(root:Node?, value:Int?):Node{
var root = root
if(root==null){
root = Node(value)
return root
}
value?.let {
if (root.data!! > value) {
root.left = insert(root.left, value)
} else {
root.right = insert(root.right, value)
}
}
return root
}
fun inorder(root: Node?){
if(root == null ) return
root.data?.let {
inorder(root.left)
print("${root.data} ")
inorder(root.right)
}
}
fun srchDelete(root: Node?, key: Int){
if(root == null){
return
}
else if (root.data == key){
if(root.left == null && root.right == null){
root.data = null
return
}
if(root.left != null && root.right == null){
root = root.left //Error Here **"Val cannot be reassigned"**
}
}
else {
srchDelete(root.left, key)
srchDelete(root.right, key)
}
}
fun main(){
var values = arrayOf(5,1,3,4,2,7)
var root:Node? = null
for(i in values){
root = insert(root, i)
}
srchDelete(root, 2)
inorder(root)
}
How can I be able to assign values in the root of type 'Node?' ?
If I put a simple code to explain my problem further. I am adding Java code that allows me to assign in function parameter and similar Kotlin code that doesn't allow me the same.
import java.util.stream.IntStream;
public class DeleteNode {
static int[] fun (int[] arr){
arr[0] = 1;
arr[1] = 9;
arr[7] = 1;
arr = new int[9]; //Java Allows Me
arr[0] = 9;
return arr;
}
public static void main(String[] args) {
int[] arr = new int[8];
int[] array = fun(arr);
IntStream.range(0, arr.length).forEach(h -> System.out.print(" " + arr[h]));
System.out.println();
IntStream.range(0, array.length).forEach(h -> System.out.print(" " + array[h]));
}
}
This Java code allowed me to assign using 'new' keyword in 'arr', now similar Kotlin code.
fun list(arr:IntArray):IntArray{
arr[0] = 1
arr[8] = 1
arr = IntArray(8){0} //Kotlin Doesn't Allow Me
arr[0] = 1
return arr
}
fun main(){
var arr = IntArray(9){0}
var array = list(arr)
for(value in arr) print("$value ")
for(value in array) print("$value ")
}
Is there a way to make Kotlin allow me to do the same too?
