[FIXED] How to return value from function in Kotlin Android

Issue

In my application I want used extension function and I want return String!
I set return value from function and I write below codes, but show me empty value!
My Extension function code :

fun Spinner.setupListWithAdapter(list: MutableList<String>): String {
    var itemSelected = ""
    val adapter = ArrayAdapter(context, android.R.layout.simple_spinner_item, list)
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
    this.adapter = adapter
    this.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
        override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
            itemSelected = list[p2]
            Log.e("categoryLog","1 : " + itemSelected)
        }
        override fun onNothingSelected(p0: AdapterView<*>?) {
        }
    }
    Log.e("categoryLog","2 : " +itemSelected)
    return itemSelected
}

When show logs in logcat, first show 2 then show 1 !
Logs :

2022-08-12 14:49:59.261 12074-12074/com.my.app E/categoryLog: 2 : 
2022-08-12 14:49:59.310 12074-12074/com.my.app E/categoryLog: 1 : Movies

Why first call log 2 then call log 1 ?!
I used this func in fragment and for this when used this in fragment show me empty value! How can I fix it?

Solution

Change your extension function like below

fun Spinner.setupListWithAdapter(list: MutableList<String>,callback: String -> Unit){
        var itemSelected = ""
        val adapter = ArrayAdapter(context, android.R.layout.simple_spinner_item, list)
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
        this.adapter = adapter
        this.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                itemSelected = list[p2]
                callback(itemSelected)
                Log.e("categoryLog","1 : " + itemSelected)
            }
            override fun onNothingSelected(p0: AdapterView<*>?) {
            }
        }
        Log.e("categoryLog","2 : " +itemSelected)
       
    }

Then in Activity or fragment

spinner.setupListWithAdapter(list){
 // It will invoked when something is selected from spinner
}

Answered By - Ammar Abdullah
Answer Checked By - Katrina (JavaFixing Volunteer)