How to do Exception Handling in Kotlin?

 An Exception in Kotlin is a runtime Exception. The process by which Exceptions are handled is called Exception Handling.
The following keywords need to be understood and used in Programming.

Here is a simple example that handles conversion from a String to Int.

fun main(args:Array<String>)

{

    try

    {

      var x:Int=  "10".toInt()

        println(x)

    }

    catch(ex:Exception)

    {

        println(ex)

    }

}

Run this program after changing the String to be converted.

We can have separate Exception Handling blocks for different Exception types.

fun main(args:Array<String>)

{

    try

    {

      var x:Int=  "10".toInt()

        println(x)

        var y:Int=9

        x=x/y

         var arr:Array<String>

         arr=Array(5,{""})

         println(arr[1])

       

    }

    catch(ex:ArithmeticException)

    {

        println("Arithmetic Exception")

        println(ex)

    }

    catch(ex:NumberFormatException)

    {

        println("Number Format Exception")

        println(ex)

    }

    catch(ex:Exception)

    {

        println("Unknown Exception")

        println(ex)

    }

    finally {

            println("Finally")

    }

}

 

Change the code to create exceptions and see the results

var x:Int=  "bnbvnbv".toInt()

Throwing an exception from a function

fun main(args:Array<String>)

{

println(factorial(-10))

}

@Throws(Exception::class)

fun factorial(n:Int):Int

{

if (n<0)

    throw Exception("-ve numbers not allowed")

    var prod:Int =1

    var i:Int

    for(i in 2..n)

        prod=prod*i

    return prod

}

Program to create our own exception

class MyException:Exception

{

    constructor(message:String) : super(message)

    {

println("Super Class Constructor with message " + message)

    }

    constructor():super()

    {

        println("Super Class Constructor")

    }

}

fun main(args:Array<String>)

{

    try

    {

      var x:Int=  "10".toInt()

       if(x==10)

           throw MyException("10 not allowed")

    }

    catch(ex:ArithmeticException)

    {

        println("Arithmetic Exception")

        println(ex)

    }

    catch(ex:NumberFormatException)

    {

        println("Number Format Exception")

        println(ex)

    }

    catch(ex:Exception)

    {

        println("Unknown Exception")

        println(ex)

    }

    finally {

            println("Finally")

    }

}