CODEWITHSUNDEEP
kotlingenerics
BabyishTank
BabyishTank

Reputation: 1482

Kotlin override generic variable

I have the following classes, but myfield variable in both NumberField and TextField cannot compile with:

Var-property type is InputField<String?>, which is not a type of overridden public abstract var inputField: InputField<*> defined in [my project]


interface FieldComponent {
    var myfield: InputField<*>  // <-- what should this be
}

interface InputField<T> {
    fun collectInput(): T
}

class NumberField(): FieldComponent{
    override lateinit var myfield: InputField<Int> // won't compile

    fun doSomething(){
        val x: Int = myfield.collectInput()
    }
}

class TextField(): FieldComponent{
    override lateinit var myfield: InputField<String> // won't compile

    fun doSomething(){
        val x: String = myfield.collectInput()
    }
}

I don't really need to know about the type in FieldComponent, but I need to have access to myfield if I have an instance of FieldComponent Can we make this work? Thank you

Upvotes: 1

Views: 325

Answers (1)

James Lan
James Lan

Reputation: 266

Make FieldComponent generic.

interface FieldComponent<T> {
    var myfield: InputField<T>
}

interface InputField<T> {
    fun collectInput(): T
}

class NumberField(): FieldComponent<Int> {
    override lateinit var myfield: InputField<Int>
    fun doSomething(){
        val x: Int = myfield.collectInput()
    }
}

class TextField(): FieldComponent<String> {
    override lateinit var myfield: InputField<String>
    fun doSomething(){
        val x: String = myfield.collectInput()
    }
}

Upvotes: 3

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