将其值设置为“”后无法过滤 AutoCompleteTextView

Question

I have an AutoCompleteTextView in my Android App, i have made a custom Adapter for it's layout and it's filter.

The issue is that the filter works fine till i cancel all i write in the AutoCompleteTextView , once i clear it the list from the constructor become empty and there isn't any item to filter and it's happen only when i empty the input value.

By default when the input is empty i would show the whole list of items the user can choose.

Here is my custom Adapter:

class FornitoriAdapter(context: Context, fornitori: MutableList<Fornitori> = mutableListOf(), resource: Int) :
    ArrayAdapter<Fornitori>(context, resource), Filterable {

    private var filteredList: MutableList<Fornitori> = mutableListOf()

    init {
        filteredList = fornitori.toMutableList()
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
        val row: View
        val holder: ViewHolder

        if (convertView == null) {
            val inflater = LayoutInflater.from(context)
            row = inflater.inflate(R.layout.list_item, parent, false)
            holder = ViewHolder(row)
            row.tag = holder
        } else {
            row = convertView
            holder = row.tag as ViewHolder
        }

        val fornitore: Fornitori = filteredList[position]

        holder.descrText.text = fornitore.desc
        holder.codeText.text = fornitore.cod

        return row
    }

    override fun getCount(): Int {
        return filteredList.size
    }

    override fun getItem(position: Int): Fornitori {
        return filteredList[position]
    }

    private class ViewHolder constructor(row: View) {
        val descrText: TextView = row.findViewById(R.id.description)
        val codeText: TextView = row.findViewById(R.id.code)
    }

    override fun getFilter(): Filter {
        return customFilter
    }

    private val customFilter = object : Filter() {
        override fun convertResultToString(resultValue: Any?): CharSequence {
            return (resultValue as Fornitori).desc
        }

        override fun performFiltering(constraint: CharSequence?): FilterResults {
            return if (constraint != null) {
                filteredList.clear()
                fornitori.forEach { // HERE FORNITORI IF I EMPTY THE INPUT BECOME LENGTH 0
                    if (it.cod.equals(constraint.toString(), ignoreCase = true) || it.desc.toLowerCase(
                            Locale.ROOT
                        ).startsWith(
                            constraint.toString().toLowerCase(
                                Locale.ROOT
                            )
                        )
                    ) {
                        filteredList.add(it)
                    }
                }
                val filterResults = FilterResults()
                filterResults.values = filteredList
                filterResults.count = filteredList.size
                filterResults
            }else {
                filteredList.clear()
                filteredList = fornitori
                val filterResults = FilterResults()
                filterResults.values = filteredList
                filterResults.count = filteredList.size
                filterResults
            }
        }

        override fun publishResults(constraint: CharSequence?, filterResults: FilterResults) {
            val filterList = filterResults.values as? MutableList<*>
            if (filterResults.count > 0) {
                filterList?.forEach {
                    add(it as Fornitori)
                }.also {
                    notifyDataSetChanged()
                }
            }
        }

    }

}

So once i start to filter or choose one of the shown items all works okay, but once i cancel the input value i'm unable to get any value from autocomplete as fornitori is set to null, like it's list has been cleared but i actually clear only the filtered list..

Answer 1

The issue comes from you first setting

filteredList = fornitori

and then calling

filteredList.clear()

As you have set filteredList to refer to fornitori then by clearing filteredList you are also clearing fornitori . So instead of just reassigning the variable, you should actually copy fornitori into filteredList .

---

Kotlin actually doesn't have a copy function for lists, but something like this is the most clear in my opinion:

filteredList.clear()
filteredList.addAll(fornitori)