kotlin error at * - None of the following functions can be called with the arguments supplied-CodePudding

while building a simple currency converter app in android kotlin I got the following error at * operator ? what could be reason for the error.

CodePudding user response：

Seems that rate variable is nullable (float? I suppose), while multiplying operation work with non null values only.

Also smart cast wasn't used here, so rate variable seems to be changeable. So I recommend to make it unchangeable (val variable), or use buffer variable like following:

val bufferRate = rate
if(bufferRate == null) {
    ...
} else {
    val convertedCurrency = fromAmount * bufferRate //here `bufferRate` should be smart casted to non nullable type
}

CodePudding user response：

You cannot use round() function with nullable Any and Float variables. Also you need to convert Any to Float. Try to convert them with this example:

var rate : Any? = 5
var fromAmount : Float? = 3.5f

val result = round(rate!!.toString().toFloat() * fromAmount!!)