AutoCompleteTextView

Remarks#

If you want to offer suggestions to the user when they type in an editable text field, you can use an AutoCompleteTextView. It provides suggestions automatically when the user is typing. The list of suggestions is displayed in a drop down menu from which the user can select one to replace the contents of the edit box.

Simple, hard-coded AutoCompleteTextView

Design (layout XML):

<AutoCompleteTextView
   android:id="@+id/autoCompleteTextView1"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_alignParentTop="true"
   android:layout_centerHorizontal="true"
   android:layout_marginTop="65dp"
   android:ems="10" />

Find the view in code after setContentView() (or its fragment or custom view equivalent):

final AutoCompleteTextView myAutoCompleteTextView = 
    (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView1);

Provide hard-coded data via an adapter:

String[] countries = getResources().getStringArray(R.array.list_of_countries);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,countries);
myAutoCompleteTextView.setAdapter(adapter);

Tip: Though the preferred way would be to provide data via a Loader of some kind instead of a hard-coded list like this.

AutoComplete with CustomAdapter, ClickListener and Filter

Main layout : activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="https://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <AutoCompleteTextView
        android:id="@+id/auto_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:completionThreshold="2"
        android:hint="@string/hint_enter_name" />
</LinearLayout>

Row layout row.xml

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

    <TextView
        android:id="@+id/lbl_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingBottom="16dp"
        android:paddingLeft="8dp"
        android:paddingRight="8dp"
        android:paddingTop="16dp"
        android:text="Medium Text"
        android:textAppearance="?android:attr/textAppearanceMedium" />
</RelativeLayout>

strings.xml

<resources>
    <string name="hint_enter_name">Enter Name</string>
</resources>

MainActivity.java

public class MainActivity extends AppCompatActivity {
    AutoCompleteTextView txtSearch;
    List<People> mList;
    PeopleAdapter adapter;
    private People selectedPerson;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mList = retrievePeople();
        txtSearch = (AutoCompleteTextView) findViewById(R.id.auto_name);
        adapter = new PeopleAdapter(this, R.layout.activity_main, R.id.lbl_name, mList);
        txtSearch.setAdapter(adapter);
        txtSearch.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int pos, long id) {
                //this is the way to find selected object/item
                selectedPerson = (People) adapterView.getItemAtPosition(pos);
            }
        });
    }

    private List<People> retrievePeople() {
        List<People> list = new ArrayList<People>();
        list.add(new People("James", "Bond", 1));
        list.add(new People("Jason", "Bourne", 2));
        list.add(new People("Ethan", "Hunt", 3));
        list.add(new People("Sherlock", "Holmes", 4));
        list.add(new People("David", "Beckham", 5));
        list.add(new People("Bryan", "Adams", 6));
        list.add(new People("Arjen", "Robben", 7));
        list.add(new People("Van", "Persie", 8));
        list.add(new People("Zinedine", "Zidane", 9));
        list.add(new People("Luis", "Figo", 10));
        list.add(new People("John", "Watson", 11));
        return list;
    }
}

Model class : People.java

public class People {

    private String name, lastName;
    private int id;

    public People(String name, String lastName, int id) {
        this.name = name;
        this.lastName = lastName;
        this.id = id;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getlastName() {
        return lastName;
    }

    public void setlastName(String lastName) {
        this.lastName = lastName;
    }
}

Adapter class : PeopleAdapter.java

public class PeopleAdapter extends ArrayAdapter<People> {

    Context context;
    int resource, textViewResourceId;
    List<People> items, tempItems, suggestions;

    public PeopleAdapter(Context context, int resource, int textViewResourceId, List<People> items) {
        super(context, resource, textViewResourceId, items);
        this.context = context;
        this.resource = resource;
        this.textViewResourceId = textViewResourceId;
        this.items = items;
        tempItems = new ArrayList<People>(items); // this makes the difference.
        suggestions = new ArrayList<People>();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (convertView == null) {
            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            view = inflater.inflate(R.layout.row, parent, false);
        }
        People people = items.get(position);
        if (people != null) {
            TextView lblName = (TextView) view.findViewById(R.id.lbl_name);
            if (lblName != null)
                lblName.setText(people.getName());
        }
        return view;
    }

    @Override
    public Filter getFilter() {
        return nameFilter;
    }

    /**
     * Custom Filter implementation for custom suggestions we provide.
     */
    Filter nameFilter = new Filter() {
        @Override
        public CharSequence convertResultToString(Object resultValue) {
            String str = ((People) resultValue).getName();
            return str;
        }

        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            if (constraint != null) {
                suggestions.clear();
                for (People people : tempItems) {
                    if (people.getName().toLowerCase().contains(constraint.toString().toLowerCase())) {
                        suggestions.add(people);
                    }
                }
                FilterResults filterResults = new FilterResults();
                filterResults.values = suggestions;
                filterResults.count = suggestions.size();
                return filterResults;
            } else {
                return new FilterResults();
            }
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            List<People> filterList = (ArrayList<People>) results.values;
            if (results != null && results.count > 0) {
                clear();
                for (People people : filterList) {
                    add(people);
                    notifyDataSetChanged();
                }
            }
        }
    };
}