Displaying AutoCompleteTextView drop down results

Question

In Xamarin, when I have an AutoCompleteTextViewor a MultiAutoCompleteTextViewwith a drop down list, can the search be done for string occurances that appear halfway through the string item?

For example, if I have the following string array:

String[] countries = new string[] { "Item1", "Item2", "Item3", "Item4", "Item5" };

And I type "Ite" into the AutoCompleteTextViewor a MultiAutoCompleteTextView, all the items above will display.

My question is in relation to the following string array:

String[] countries = new string[] { "1abcd", "2abdc", "1234", "Item42abcd", "Item5" };

Is it possible to type "abcd" into the AutoCompleteTextViewor a MultiAutoCompleteTextView, and the following will be displayed:

"1abcd", "2abdc", "Item42abcd"

Answer 1

I try to keep my code cross-platform compatible so I usually use an adapter based on ObservableCollection and in Android it implements both IListAdapter and ISpinnerAdapter. This is to avoid performance issues with large datasets. Here is a little demo code for the basic functionality just by using EditText and a basic ArrayAdapter:

[Activity (Label = "SearchBox", MainLauncher = true)]
public class MainActivity : Activity
{
    private readonly string[] countries = { "1abcd", "2abdc", "1234", "Item42abcd", "Item5" };

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate (bundle);

        // Set our view from the "main" layout resource
        SetContentView (Resource.Layout.Main);

        var editText = this.FindViewById<EditText> (Resource.Id.editText1);
        var listView = this.FindViewById<ListView> (Resource.Id.listView1);

        listView.Adapter = new ArrayAdapter (this, Resource.Layout.ListItem, countries);

        editText.TextChanged += (sender, e) => listView.Adapter = 
            new ArrayAdapter (
                this, 
                Resource.Layout.ListItem, 
                countries.Where (a => a.Contains (editText.Text)).ToArray ());
    }
}

Answer 2

You have to create your own Adapter and filter yourself, by default adapter works with startsWith, you have to change it contains.

The full example here.

public class AutoCompleteAdapter extends ArrayAdapter<String> implements Filterable {

    private ArrayList<String> fullList;
    private ArrayList<String> mOriginalValues;
    private ArrayFilter mFilter;
    private MainActivity mActivity;

    public AutoCompleteAdapter(MainActivity activity, int resource, List<String> objects) {

        super(activity, resource, objects);
        fullList = (ArrayList<String>) objects;
        mOriginalValues = new ArrayList<String>(fullList);
        mActivity = activity;

    }

    @Override
    public int getCount() {
        return fullList.size();
    }

    @Override
    public String getItem(int position) {
        return fullList.get(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return super.getView(position, convertView, parent);
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ArrayFilter();
        }
        return mFilter;
    }

    @Override
    public View getDropDownView(int position, View convertView, ViewGroup parent) {
        TextView v = (TextView) super.getView(position, convertView, parent);

        if (v == null) {
            v = new TextView(mActivity);
        }
        v.setText(fullList.get(position));
        v.setTextColor(mActivity.getResources().getColor(R.color.textColor));
        v.setTextSize(mActivity.getResources().getDimension(R.dimen.my_orders_spinner_text_size));
        v.setPadding(
                (int)mActivity.getResources().getDimension(R.dimen.my_orders_spinner_text_padding),
                (int)mActivity.getResources().getDimension(R.dimen.my_orders_spinner_text_padding),
                (int)mActivity.getResources().getDimension(R.dimen.my_orders_spinner_text_padding),
                (int)mActivity.getResources().getDimension(R.dimen.my_orders_spinner_text_padding));
        return v;
    }


    private class ArrayFilter extends Filter {
        private Object lock;

        @Override
        protected FilterResults performFiltering(CharSequence prefix) {
            FilterResults results = new FilterResults();

            if (mOriginalValues == null) {
                synchronized (lock) {
                    mOriginalValues = new ArrayList<String>(fullList);
                }
            }

            if (prefix == null || prefix.length() == 0) {
                synchronized (lock) {
                    ArrayList<String> list = new ArrayList<String>(mOriginalValues);
                    results.values = list;
                    results.count = list.size();
                }
            } else {
                final String prefixString = prefix.toString().toLowerCase();

                ArrayList<String> values = mOriginalValues;
                int count = values.size();

                ArrayList<String> newValues = new ArrayList<String>(count);

                for (int i = 0; i < count; i++) {
                    String item = values.get(i);
                    if (item.toLowerCase().contains(prefixString)) {
                        newValues.add(item);
                    }

                }

                results.values = newValues;
                results.count = newValues.size();
            }

            return results;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {

            if(results.values!=null){
                fullList = (ArrayList<String>) results.values;
            }else{
                fullList = new ArrayList<String>();
            }
            if (results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

Answer 3

• Taking suggestion strings in an array name item. Taking AutoCompleteTextView reference from auto_complete_string.xml file. Adding item array to adapter and add adapter to AutoCompleteTextView.

Implementation

public class AutoCompleteString extends Activity implements  OnItemClickListener, 
OnItemSelectedListener  {

// Initialize variables

AutoCompleteTextView textView=null;
private ArrayAdapter<String> adapter;

//These values show in autocomplete
String item[]={
          "January", "February", "March", "April",
          "May", "June", "July", "August",
          "September", "October", "November", "December"
        };

@Override
public void onCreate(Bundle bundle) {
    super.onCreate(bundle);

    setContentView(R.layout.auto_complete_string);


    // Initialize AutoCompleteTextView values

        // Get AutoCompleteTextView reference from xml
        textView = (AutoCompleteTextView) findViewById(R.id.Months);

        //Create adapter    
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, item);

        textView.setThreshold(1);

       //Set adapter to AutoCompleteTextView
        textView.setAdapter(adapter);  

}
}

Check out this Example