Using EditText in Android with Kotlin

Implementing Autocomplete Functionality in EditText with Kotlin

Autocomplete functionality is a useful feature for enhancing the user experience in Android apps. When using EditText, it can be helpful to suggest possible values based on the user’s input. In this section, we’ll discuss how to implement autocomplete functionality using Kotlin.

First, let’s have a brief overview of autocomplete functionality. Autocomplete suggests possible values to the user as they type in the EditText field, making it easier and faster for the user to enter data. This functionality can be used in various scenarios, such as searching for items, filtering results, or suggesting usernames or email addresses.

To implement autocomplete functionality in an EditText using Kotlin, we need to create a data source that will provide suggestions to the user. This data source can be a local database or a remote API. We can then use an ArrayAdapter to display the suggestions in a dropdown list.

Let’s look at an example of using a local database as a data source for autocomplete. In this example, we’ll create a simple database with a table of cities and their corresponding zip codes. We’ll then use this database to provide suggestions as the user types in a city name.

First, let’s create a layout file for our EditText field and add it to our activity’s layout file using a LinearLayout:

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

    <EditText
        android:id="@+id/city_input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/city_hint" />

</LinearLayout>

Next, let’s create our database with a table of cities and their zip codes. We’ll use Room, a persistence library provided by Android, to create and interact with our database. We’ll define an entity class for our cities table and a DAO (Data Access Object) interface to perform database operations.

@Entity(tableName = "cities")
data class City(
    @PrimaryKey val id: Int,
    val name: String,
    val zipCode: String
)

@Dao
interface CityDao {
    @Query("SELECT * FROM cities WHERE name LIKE :query")
    fun getCitiesByName(query: String): List<City>
}

@Database(entities = [City::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun cityDao(): CityDao
}

Autocomplete functionality is a useful feature for enhancing the user experience in Android apps. When using EditText, it can be helpful to suggest possible values based on the user’s input. In this section, we’ll discuss how to implement autocomplete functionality using Kotlin.

First, let’s have a brief overview of autocomplete functionality. Autocomplete suggests possible values to the user as they type in the EditText field, making it easier and faster for the user to enter data. This functionality can be used in various scenarios, such as searching for items, filtering results, or suggesting usernames or email addresses.

To implement autocomplete functionality in an EditText using Kotlin, we need to create a data source that will provide suggestions to the user. This data source can be a local database or a remote API. We can then use an ArrayAdapter to display the suggestions in a dropdown list.

Let’s look at an example of using a local database as a data source for autocomplete. In this example, we’ll create a simple database with a table of cities and their corresponding zip codes. We’ll then use this database to provide suggestions as the user types in a city name.

First, let’s create a layout file for our EditText field and add it to our activity’s layout file using a LinearLayout:

XML Example:

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

    <EditText
        android:id="@+id/city_input"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/city_hint" />

</LinearLayout>

Next, let’s create our database with a table of cities and their zip codes. We’ll use Room, a persistence library provided by Android, to create and interact with our database. We’ll define an entity class for our cities table and a DAO (Data Access Object) interface to perform database operations.

Kotlin example:

@Entity(tableName = "cities")
data class City(
    @PrimaryKey val id: Int,
    val name: String,
    val zipCode: String
)

@Dao
interface CityDao {
    @Query("SELECT * FROM cities WHERE name LIKE :query")
    fun getCitiesByName(query: String): List<City>
}

@Database(entities = [City::class], version = 1)
abstract class AppDatabase : RoomDatabase() {
    abstract fun cityDao(): CityDao
}

In our activity, we’ll initialize our database and retrieve the list of cities that match the user’s input using a TextWatcher. We’ll then create an ArrayAdapter to display the suggestions in a dropdown list below the EditText field.

class MainActivity : AppCompatActivity() {

    private lateinit var db: AppDatabase

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        db = Room.databaseBuilder(
            applicationContext,
            AppDatabase::class.java, "database-name"
        ).build()

        val cityInput = findViewById<EditText>(R.id.city_input)

        cityInput.addTextChangedListener(object : TextWatcher {
            override fun afterTextChanged(s: Editable?) {}

            override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {}

            override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
                s?.let {
                    val cities = db.cityDao().getCitiesByName("$it%")
                    val adapter = ArrayAdapter(this@MainActivity, android.R.layout.simple_dropdown_item_1line, cities.map { it.name })
                    cityInput.setAdapter(adapter)
                }
            }
        })
    }
}