Hello, Views:

Auto Complete

To create a text entry widget that provides auto-complete suggestions, use the AutoCompleteTextView widget. Suggestions are received from a collection of strings associated with the widget through an ArrayAdapter.

In this tutorial, you will create a AutoCompleteTextView widget that provides suggestions for a country name.

Start a new project named HelloAutoComplete.

Create an XML file named list_item.xml and save it inside the res/layout/ folder. Edit the file to look like this:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp"
    android:textSize="16sp"
    android:textColor="#000">
</TextView>

This file defines a simple TextView that will be used for each item that appears in the list of suggestions.

Open the res/layout/main.xml file and insert the following:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="horizontal"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"
    android:padding="5dp">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Country" />
    <AutoCompleteTextView android:id="@+id/autocomplete_country"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginLeft="5dp"/>
</LinearLayout>

The TextView is a label that introduces the AutoCompleteTextView widget.

Open HelloAutoComplete.java and insert the following code for the onCreate() method:
```
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.autocomplete_country);
    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item, COUNTRIES);
    textView.setAdapter(adapter);
}
```
After the content view is set to the main.xml layout, the AutoCompleteTextView widget is captured from the layout with findViewById(int). A new ArrayAdapter is then initialized to bind the list_item.xml layout to each list item in the COUNTRIES string array (defined in the next step). Finally, setAdapter() is called to associate the ArrayAdapter with the AutoCompleteTextView widget so that the string array will populate the list of suggestions.

Inside the HelloAutoComplete class, add the string array:

static final String[] COUNTRIES = new String[] {
  "Afghanistan", "Albania", "Algeria", "American Samoa", "Andorra",
  "Angola", "Anguilla", "Antarctica", "Antigua and Barbuda", "Argentina",
  "Armenia", "Aruba", "Australia", "Austria", "Azerbaijan",
  "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium",
  "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia",
  "Bosnia and Herzegovina", "Botswana", "Bouvet Island", "Brazil", "British Indian Ocean Territory",
  "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burundi",
  "Cote d'Ivoire", "Cambodia", "Cameroon", "Canada", "Cape Verde",
  "Cayman Islands", "Central African Republic", "Chad", "Chile", "China",
  "Christmas Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo",
  "Cook Islands", "Costa Rica", "Croatia", "Cuba", "Cyprus", "Czech Republic",
  "Democratic Republic of the Congo", "Denmark", "Djibouti", "Dominica", "Dominican Republic",
  "East Timor", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea",
  "Estonia", "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji", "Finland",
  "Former Yugoslav Republic of Macedonia", "France", "French Guiana", "French Polynesia",
  "French Southern Territories", "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar",
  "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guinea", "Guinea-Bissau",
  "Guyana", "Haiti", "Heard Island and McDonald Islands", "Honduras", "Hong Kong", "Hungary",
  "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Israel", "Italy", "Jamaica",
  "Japan", "Jordan", "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",
  "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg",
  "Macau", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Marshall Islands",
  "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia", "Moldova",
  "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",
  "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand",
  "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "North Korea", "Northern Marianas",
  "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru",
  "Philippines", "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",
  "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe", "Saint Helena",
  "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon",
  "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Saudi Arabia", "Senegal",
  "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands",
  "Somalia", "South Africa", "South Georgia and the South Sandwich Islands", "South Korea",
  "Spain", "Sri Lanka", "Sudan", "Suriname", "Svalbard and Jan Mayen", "Swaziland", "Sweden",
  "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "The Bahamas",
  "The Gambia", "Togo", "Tokelau", "Tonga", "Trinidad and Tobago", "Tunisia", "Turkey",
  "Turkmenistan", "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",
  "Ukraine", "United Arab Emirates", "United Kingdom",
  "United States", "United States Minor Outlying Islands", "Uruguay", "Uzbekistan",
  "Vanuatu", "Vatican City", "Venezuela", "Vietnam", "Wallis and Futuna", "Western Sahara",
  "Yemen", "Yugoslavia", "Zambia", "Zimbabwe"
};

This is the list of suggestions that will be provided in a drop-down list when the user types into the AutoCompleteTextView widget.

Run the application.

As you type, you should see something like this:

More Information

Note that using a hard-coded string array is not a recommended design practice because your application code should focus on behavior, not content. Application content such as strings should be externalized from the code in order to make modifications to the content easier and facilitate localization of the content. The hard-coded strings are used in this tutorial only to make it simple and focus on the AutoCompleteTextView widget. Instead, your application should declare such string arrays in an XML file. This can be done with a <string-array< resource in your project res/values/strings.xml file. For example:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="countries_array">
        <item>Bahrain</item>
        <item>Bangladesh</item>
        <item>Barbados</item>
        <item>Belarus</item>
        <item>Belgium</item>
        <item>Belize</item>
        <item>Benin</item>
    </string-array>
</resources>

To use these resource strings for the ArrayAdapter, replace the original ArrayAdapter constructor line with the following:

String[] countries = getResources().getStringArray(R.array.countries_array);
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.list_item, countries);

References

ArrayAdapter
AutoCompleteTextView

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