Unable to access variable from innerclass : Kotlin android

Question

I am new to Kotlin development in android. here I am trying to access a variable defined in a class from it's inner class as below.

class MainActivity : AppCompatActivity() {

    var frags: MutableList<Fragment> = mutableListOf()

//.............onCreate and other methods ....

    internal class CustAdapter(var arrayList: ArrayList<NavigationData>) : RecyclerView.Adapter<CustAdapter.MyViewHolder>() {
    override fun onBindViewHolder(holder: MyViewHolder?, position: Int) {
        holder!!.bindItems(arrayList[position])
    }

    override fun getItemCount(): Int {
        return arrayList.size
    }
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustAdapter.MyViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.navigation_item, parent, false)
        return MyViewHolder(v)
    }

    class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        fun bindItems(data: NavigationData) {


            itemView.setOnClickListener {
                   frags.add(BoardFrag()) ///// here i'm getting error "unresolved symbol"

            }
        }
    }
}    
}

inside inner class MyViewHolder it is not allowing me to access any variable of outer scope.

even I'm unable to access view ids imported from import kotlinx.android.synthetic.main.activity_main.* inside inner class methods.

I was able to access variables in such a way in java but i have read many question on stackoverflow but i didn't get answer yet.

Use inner keyword instead of internal class parent { val m=1; inner class child{ print(m)} } — lava
– lava, Commented Sep 22, 2021 at 7:28

Leandro Borges Ferreira · Accepted Answer · 2017-09-23 05:02:16Z

91

You should use the inner modifier in your adapter.

This modifier makes the inner class have access to the members of the outer class

Reference: https://kotlinlang.org/docs/reference/nested-classes.html

edited Sep 23, 2017 at 5:02

answered Sep 23, 2017 at 4:52

Leandro Borges Ferreira

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3 Comments

Shankar Over a year ago

Thanks for your solution. This tiny mistake was bitting me from two days and you saved my another day

Leandro Borges Ferreira Over a year ago

You are welcome! The name internal and inner is really tricky... Keep with protected would be better I guess

Shankar Over a year ago

I do not know the difference between protected and internal and inner but i will try to sort it out on my own

Vivek Pratap Singh · Accepted Answer · 2024-01-22 04:45:45Z

52

Define your nested class as inner then you will be able to access an outer class's member variable.

class OuterClass{

var accessMe ="access me from Inner Class"

    inner class InnerClass{

       //....

   
        fun accessingOuterClassVariable(){

           accessMe = "Now the variable is accessed"

        }

    }

}

edited Jan 22, 2024 at 4:45

answered Feb 16, 2018 at 8:37

Vivek Pratap Singh

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2 Comments

IgorGanapolsky Over a year ago

Where is the call-site for var accessMe?

Vivek Pratap Singh Over a year ago

@IgorGanapolsky Please check , I have updated the answer.

Pouya Danesh · Accepted Answer · 2018-07-10 07:54:22Z

10

to answer this question for the fast an easy way i would do something like following :

class OuterClass{

private var accessibleInside: CustomObject? = null
inner class InnerClass{

    //....
}

now the CustomObject could be anything from Context to String hope this helps someone.

answered Jul 10, 2018 at 7:54

Pouya Danesh

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