Recipe

• Create a layout file that contains an AutoCompleteTextView, such as Main.axml in the example code:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">

<AutoCompleteTextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/AutoCompleteInput"
/>
</LinearLayout>

• Use the Main.axml as the view for your activity:

SetContentView (Resource.Layout.Main);

• Create a string array containing the options you would like to be autocompleted:

var autoCompleteOptions = new String[] { "Hello", "Hey", "Heja", "Hi", "Hola", "Bonjour", "Gday", "Goodbye", "Sayonara", "Farewell", "Adios" };

• Use the array to populate an ArrayAdapter with the built-in SimpleDropDownItem1Line layout:

ArrayAdapter autoCompleteAdapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleDropDownItem1Line, autoCompleteOptions);

• Find the instance of the AutoCompleteTextView in the layout and assign the ArrayAdapter:

var autocompleteTextView = FindViewById<AutoCompleteTextView>(Resource.Id.AutoCompleteInput);
autocompleteTextView.Adapter = autoCompleteAdapter;

• When the control has focus and the user is typing, matching entries will automatically be displayed for them to choose from.

Additional Information

To use a much longer list of autocomplete options than the array in step 3, use the code below to load the list from a file:

// instead of the small array of greetings, use a large dictionary of words loaded from a file
Stream seedDataStream = Assets.Open(@"WordList.txt");
List<string> lines = new List<string>();

using (StreamReader reader = new StreamReader(seedDataStream)) {
    string line;
    while ((line = reader.ReadLine()) != null) {
        lines.Add(line);
    }
}
string[] wordlist = lines.ToArray();
ArrayAdapter dictionaryAdapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleDropDownItem1Line, wordlist);
autocompleteTextView.Adapter = dictionaryAdapter;

The WordList.txt file is included in the example project.