CODEWITHSUNDEEP
oopcastingkotlin
Usman
Usman

Reputation: 87

The cast can never be succeed

I am new in Kotlin and I currently study about the concept of OOP

I am trying to do a cast with this code, but I'm facing an error:

    open class Operations1(){
        open  fun sum(n1:Int , n2:Int):Int{
            return n1+ n2
        }
        fun sub(n1:Int , n2:Int):Int{
            return n1- n2
        }
    }
    class multiOperations1():Operations(){
        override  fun sum(n1:Int , n2:Int):Int{
            return n1+ n2 +5
        }
        fun mul(n1:Int , n2:Int):Int{
            return n1* n2
        }
        fun div(n1:Int , n2:Int):Int{
            return n1/ n2
        }
    }
    fun main(args:Array<String>){

        var oper = Operations()
        var inlit  = multiOperations1() as Operations1
        println("Enter first number")
        var n1:Int = readLine()!!.toInt()
        println("Enter Second Number")
        var n2:Int = readLine()!!.toInt()

        var sum = inlit.sum(n1 , n2)
        var sub = inlit.sub(n1 , n2)
        println("Sum: " + sum)
        println("Sub: " + sub)
    }

Screen shot of the code

This is the screen shot of the code

error:

This is the error which my program through

Upvotes: 3

Views: 18415

Answers (3)

Zulqarnain
Zulqarnain

Reputation: 651

To achieve you can use Gson and avoid boilerplate code.

var operation= Operations(....)

val json = Gson().toJson(operation)

val multiOperations:MultiOperations =Gson().fromJson(json, MultiOperations::class.java)

Upvotes: 2

Rahul
Rahul

Reputation: 10625

Either you can use -

 var inlit  = multiOperations1() as Operations

You can typecast your derived class to parent class. In your case multiOperations1 class have a parent class Operations.

Just a suggestion start you class name like multiOperations1 from capital letter.

Upvotes: 0

zsmb13
zsmb13

Reputation: 89548

You seem to have both an Operations and an Operations1 class. Your multiOperations1 class inherits from Operations instead of Operations1, so you won't be able to cast it to Operations1 (unless Operations is a subclass of Operations1).

I assume you wanted to inherit from Operations1 instead, like this:

class multiOperations1(): Operations1() {
    ...
}

A note on conventions: class names in Kotlin usually follow Java conventions, and use upper camel case, so you should probably name your class MultiOperations1 instead.

Upvotes: 3

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