AutoCompleteTextView in Kotlin

Android AutoCompleteTextView is an editable text view which shows a list of suggestions when user starts typing text. When a user starts typing, a dropdown menu will be there based on the entered characters, defined in threshold limit and user can choose an item from list to replace the text.

The AutoCompleteTextView is a subclass of EditText class so we can easily inherit all the properties of EditText as per our requirements.

The dropdown list will be obtained suing data adaptor and these suggestions will be appeared only after entering the minimum number characters defined in the Threshold limit. The Threshold limit is used to define the minimum number of characters the user must type to see the dropdown list of suggestions.



In android, we can create a AutoCompleteTextView control in two ways either manually in XML file or create it in Activity file programmatically.

First we create a new project by following the below steps:

  1. Click on File, then New => New Project.
  2. After that include the Kotlin support and click on next.
  3. Select the minimum SDK as per convenience and click next button.
  4. Then select the Empty activity => next => finish.

Different attributes of AutoCompleteText widget –

XML Attributes Description
android:id Used to uniquely identify the control.
android:gravity Used to specify how to align the text like left, right, center, top, etc.
android:text Used to set the text.
android:textSize Used to set the size of the text.
android:textStyle Used to set the style of the text like bold, italic.
android:background Used to set background color of the Text View.
android:hint Used to set display hint text in the Text View.
android:maxHeight Used to set maximum height of the Text view.
android:maxWidth Used to set maximum width of the Text view.
android:padding Used to set the padding from left, right, top and bottom.

Add the AutoCompleteTextView in activity_main.xml

In this file, we will add the AutoCompleteTextView and Button widget and set their attributes so that it can be accessed in the kotlin file.

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http:// schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/linear_layout"
    android:gravity="center">
  
    <AutoCompleteTextView
        android:id="@+id/autoTextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:hint="@string/hint"/>
  
    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/submit"/>
  
</LinearLayout>

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Modify the strings.xml file to add the string-array

Here, we will specify the name of the activity and define other strings which can be used at different places in our activity. Another important thing is that we will define string_array which contains the items for the suggestion list of AutoCompleteTextView.

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<resources>
    <string name="app_name">AutoCompleteTextViewInKotlin</string>
    <string name="hint">Please type language...</string>
    <string name="submit">Submit</string>
    <string name="submitted_lang">Submitted language:</string>
  
    <string-array name="Languages">
        <item>Java</item>
        <item>Kotlin</item>
        <item>Swift</item>
        <item>Python</item>
        <item>Scala</item>
        <item>Perl</item>
        <item>Javascript</item>
        <item>Jquery</item>
    </string-array>
  
</resources>

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Access the CompleteTextView in MainActivity.kt file

First of all, we declare a variable autotextview to access the widget from the XML layout.

val autotextView = findViewById<AutoCompleteTextView>(R.id.autoTextView)

then, we declare another variable languages to get the items of the string-array from the strings.xml file.

val languages = resources.getStringArray(R.array.Languages)

Create an adaptor and add into the AutoCompleteTextView of LinearLayout using

val adapter = ArrayAdapter(this,
       android.R.layout.simple_list_item_1, languages)
        autotextView.setAdapter(adapter)

We are familiar with further activities in previous articles like accessing button and set OnClickListener etc.

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package com.geeksforgeeks.myfirstkotlinapp
  
    import android.os.Bundle import android.view.View import androidx.appcompat.app.AppCompatActivity import android.widget.ArrayAdapter import android.widget.AutoCompleteTextView import android.widget.Button import android.widget.Toast
  
    class MainActivity : AppCompatActivity() {
  
    override fun onCreate(savedInstanceState: Bundle?)
    {
        super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
  
                val autotextView
            = findViewById<AutoCompleteTextView>(R.id.autoTextView)
            // Get the array of languages
            val languages
            = resources.getStringArray(R.array.Languages)
              // Create adapter and add in AutoCompleteTextView
              val adapter
            = ArrayAdapter(this,
                           android.R.layout.simple_list_item_1, languages)
                  autotextView.setAdapter(adapter)
  
                      val button
            = findViewById<Button>(R.id.btn) if (button != null)
        {
            button ?.setOnClickListener(View.OnClickListener {
                        val enteredText = getString(R.string.submitted_lang) + " " + autotextView.getText() Toast.makeText(this @MainActivity, enteredText, Toast.LENGTH_SHORT).show()
                    })
        }
    }
}

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AndroidManifest.xml file

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<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http:// schemas.android.com/apk/res/android"
package="com.geeksforgeeks.myfirstkotlinapp">
  
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
  
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>
  
</manifest>

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