Two Spinners Populated By Same ArrayList - kotlin

Question

So I am trying to populate two Spinners in the same Fragment, both using the same list, but to display different items.
I have the following data class:
data class ProductTypeObject (
//ProductType fields (2 fields)
var productType: String = "",
var productGroup: String = "",
#ServerTimestamp
var dateEditedTimestamp: Date? = null,
#Exclude #set:Exclude #get:Exclude
var productTypeID: String = ""
) : Serializable {
override fun toString(): String {
return productType
}
}
The Spinner is populated in the Fragment when the list is observed from the ViewModel as below:
// Observe ProductTypes and populate Spinner
businessViewModel.allAppDataProductTypes.observe(viewLifecycleOwner, Observer { productTypeArrayList ->
if (!productTypeArrayList.isNullOrEmpty()){
val adapter = ArrayAdapter(requireContext(), android.R.layout.simple_spinner_item, productTypeArrayList)
binding.inventoryAddEditProductGroupSpinner.adapter = adapter
}
})
This shows a list of product types as I have specified this in the toString()of the object, but is there a way to direct a second Spinner to show a list ofproduct group?

Answer 1

If you don't need to retrieve the values from the spinners, it's easiest to map the values to a new list:
businessViewModel.allAppDataProductTypes.observe(viewLifecycleOwner, Observer { productTypeArrayList ->
if (!productTypeArrayList.isNullOrEmpty()){
//...
val adapter2 = ArrayAdapter(requireContext(), android.R.layout.simple_spinner_item,
productTypeArrayList.map(ProductTypeObject::productGroup)
//...
}
})
If you need both Spinners to be able to retrieve the original item type, then you can't use the ArrayAdapter class as is, since it relies purely on the toString() of your class. You can subclass it like this for a more flexible version that lets you pass property or lambda that is used instead of toString(). I didn't test it, but I think it will do what you want. If you use this class, you don't need to override toString() in your original data class.
class CustomArrayAdapter<T : Any>(
context: Context,
items: List<T>,
val itemToCharSequence: T.() -> CharSequence = Any::toString
) : ArrayAdapter<T>(context, 0, items) {
private val inflater = LayoutInflater.from(context)
override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
return (convertView ?: inflater.inflate(android.R.layout.simple_spinner_item, parent, false))
.apply {
val item = getItem(position)!! // will never be null inside getView()
(this as TextView).text = itemToCharSequence(item)
}
}
}
Usage:
val typeAdapter = CustomArrayAdapter(requireContext(), productTypeArrayList, ProductTypeObject::productType)
val groupAdapter = CustomArrayAdapter(requireContext(), productTypeArrayList, ProductTypeObject::productGroup)