I'm having Trouble getting string values from a spinner without it crashing my app , I want to make a choice according to the 2 pair of selected items in the when Function

val convertFrom = spnConvertFrom.selectedItem.toString()
val convertTo = spnConvertTo.selectedItem.toString()
val value = initialAmount.toString()
var valor2= value.toDouble()
when {
    //Condicion
    (convertFrom.equals("NIO") && convertTo.equals("USD")) -> currencyConverted.apply {
        text = "Something"
    }
    else -> Toast.makeText(this, "Error", Toast.LENGTH_SHORT).show()
}

I've tried to switch the syntax a bit from = to .equals() (Same thing) Read something about it being null at the moment of the comparison but have no idea how to check it , I'm quite new to Kotlin and programing in android

CodePudding user response：

There are several lines which could case an NPE

1. The lines where you are retrieving the selectedItem. You can handle those by adding the ? operator after the spinner instances
2. The line where you convert value to a Double. You can avoid the error by using toDoubleOrNulland providing a default value in case thatvalue` is not numeric
3. The line where you set the text of currencyConverted. If it is optional you should add the ? operator there as well:

 val convertFrom = spnConvertFrom?.selectedItem.toString()
 val convertTo = spnConvertTo?.selectedItem.toString()
 val value = initialAmount.toString()
 var valor2 = value.toDoubleOrNull() ?: 0.0

when {
    //Condicion
    (convertFrom.equals("NIO") && convertTo.equals("USD")) -> currencyConverted?.text = "Something"
    else -> Toast.makeText(this, "Error", Toast.LENGTH_SHORT).show()
}