How to use AutoCompleteTextView in Android?

AutoCompleteTextView is an editable text view that shows completion suggestions automatically while the user is typing. The list of suggestions is displayed in a drop down menu from which the user can choose an item. The list of suggestions is obtained from a data adapter, usually an array adapter.

Let us create a simple AutoCompleteTextView to enter a countries and supported by a list of countries for auto completion.

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <AutoCompleteTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/autoCompleteTextView"
        android:hint="Enter Country"/>

</LinearLayout>

Some of the other XML attributes that you can define:

In Java, create an array of the countries that you want to allow auto complete for.  Then, we create an ArrayAdapter of type String initialised by this array. An ArrayAdapter takes in 3 parameters: Context (Main Activity), layout resource id and the array (in this case the String array). For the layout, we use one of the default android provided simple dropdown layouts (android.R.layout.simple_dropdown_item_1line)

We then find the AutoCompleteTextView by id and set this ArrayAdapter to it.

Here’s the final java code:

public class MainActivity extends AppCompatActivity {
    private String[] countries = 
             {"India", "USA", "Russia", "China", "Japan", "Indonesia"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
     
        // Find the view
        AutoCompleteTextView autoCompleteTextView = 
                (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);
        // Create an array adapter initialised with the countries array
        ArrayAdapter adapter = new ArrayAdapter<>(this,
                android.R.layout.simple_dropdown_item_1line, countries);
        // Set the adapter to the AutoCompleteTextView
        autoCompleteTextView.setAdapter(adapter);
    }
}