Print all permutations of a string in kotlin

Kotlin program for Print all permutations of a string. Here more information.

// Kotlin program for
// Print all permutations of a string
class Permutation
{
	// Swapping two string elements by index
	fun swap(info: String, size: Int, a: Int, b: Int): String
	{
      	var text = info;
		// Check valid location of swap element
		if ((a >= 0 && a < size) && (b >= 0 && b < size))
		{
			// Get first character
			val first: Char = text.get(a);
			// Get second character
			val second: Char = text.get(b);
			// Put character
			text = text.substring(0, b) + first.toString() + 
              text.substring(b + 1);
			text = text.substring(0, a) + second.toString() + 
              text.substring(a + 1);
		}
		return text;
	}
	// Method which is print all permutations of given string
	fun findPermutation(info: String, n: Int, size: Int): Unit
	{
		if (n > size)
		{
			return;
		}
		if (n == size)
		{
			println(info);
			return;
		}
      	var text = info;
		var i: Int = n;
		while (i < size)
		{
			// Swap the element
			text = this.swap(text, size, i, n);
			this.findPermutation(text, n + 1, size);
			// Swap the element
			text = this.swap(text, size, i, n);
			i += 1;
		}
	}
}
fun main(args: Array < String > ): Unit
{
	val task: Permutation = Permutation();
	var text: String = "ABC";
	var size: Int = text.length;
	task.findPermutation(text, 0, size);
	println();
	text = "abcd";
	size = text.length;
	task.findPermutation(text, 0, size);
}

Output

ABC
ACB
BAC
BCA
CBA
CAB

abcd
abdc
acbd
acdb
adcb
adbc
bacd
badc
bcad
bcda
bdca
bdac
cbad
cbda
cabd
cadb
cdab
cdba
dbca
dbac
dcba
dcab
dacb
dabc