We can use the arrayOf() function to create a new array and pass the array elements as arguments to the function. Syntax :

 arrayOf(/* Elements */)
 

Example :

 fun main() {
    val nums = arrayOf(12, 15, 20, 35) // Creates an array of 4 ints
}
 

We can create a new int array using IntArray constructor too. We have to pass a size in it and it’ll return an array of that size full of zeroes :

 IntArray(/* Elements */)
 

Example :

 fun main() {
    val nums = IntArray(3) // Creates an array of 3 ints (zeroes)
}
 

Similarly, we can create FloatArray, DoubleArray, LongArray, BooleanArray & CharArray. Numerical arrays are filled with zeroes, BooleanArray with false and CharArray with character of code 0.

To print all the elements of an array, we can use the predefined contentToString() function :

 /* array */.contentToString()
 

Example :

 fun main() {
    val nums = arrayOf(1, 2, 3)
    println("nums = ${nums.contentToString()}")
}
 

Alternatively, we can iterate (loop) through the array, visit every item and print it. We can use the for loop or the forEach function like this :

 fun main() {
    val nums = arrayOf(12, 15, 20, 35)

    // Using for loop 
    for (num in nums) {
        print("$num, ")
    }

    // OR Using forEach function
    nums.forEach {
        print("$it, ")
    }
}

/* Output :

12, 15, 20, 35, 
*/
 

While looping through an array, if we want index along with the element, we can use forEachIndexed function :

 /* array */.forEachIndexed { index, element ->
	// Code
}
 

Example :

 fun main() {
    val nums = arrayOf(12, 15, 20, 35)

    nums.forEachIndexed { index, i ->
        println("nums[$index] = $i")
    }
}

/* Output :

nums[0] = 12
nums[1] = 15
nums[2] = 20
nums[3] = 35
 */
 

In Array, elements are arranged in linear fashion so each element has a fixed position (index). Indexing starts from 0 so first element is stored at index 0, second element at index 1 and so on. If an array is of size n then indices are in range 0…(n-1).

To access or modify an element, we need its index. We can access the element at a given index using indexing operator [] or .get() function :

 fun main() {
    val nums = arrayOf(12, 15, 20, 35)

    // Using indexing operator []
    println(nums[2]) // Prints 3rd element : 20

    // OR Using .get() function
    println(nums.get(0)) // Prints 1st element : 12
}
 

To check whether an element is present in the Array, we can use the contains() function :

 /* array */.contains(/* Element */)
 

Example :

 fun main() {
    val nums = arrayOf(1, 2, 3)
    println("contains(1) = ${nums.contains(1)}")
    println("contains(4) = ${nums.contains(4)}")
}

/* Output :
contains(1) = true
contains(4) = false
*/
 

To modify the element at a given index, we can use either the indexing operator & assignment operator or the set() function :

 array[/* index */] = /* new value */
// OR
array.set(/* index */, /* new value */)
 

Example :

 fun main() {
    val nums = arrayOf(12, 15, 20, 35)

    println("nums[0] = ${nums[0]}") // Prints 12 
    
    // Update 1st element to 10
    nums[0] = 10    
    // Update 3rd element to 25
    nums.set(2, 25)

    println("nums[0] = ${nums[0]}") // Prints 10
    println("nums[2] = ${nums[2]}") // Prints 25
}
 

• ArrayOutOfBoundsException

  When trying to access an element at index out of the range of array indices, we get ArrayOutOfBoundsException. Example :

   fun main() {
      val nums = IntArray(3)
      println(nums[3]) // Trying to access 4th element, doesn't exist!
  }
  
  /* Output :
  
  Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3
  */