How to dynamically update a ListView on Android Kotlin?

Kotlin Apps/ApplicationsMobile Development

This example demonstrates how to dynamically update a ListView on Android Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇉ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical"
   android:padding="4dp">
   <EditText
      android:id="@+id/editText"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:hint="Enter an item here"
      android:inputType="text" />
   <Button
      android:id="@+id/btnAdd"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/editText"
      android:text="Add item" />
   <ListView
      android:id="@+id/listView"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
   android:layout_below="@id/btnAdd" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.Button
import android.widget.EditText
import android.widget.ListView
class MainActivity : AppCompatActivity() {
   lateinit var editText: EditText
   lateinit var button: Button
   lateinit var listView: ListView
   var list: ArrayList<String> = ArrayList()
   lateinit var arrayAdapter: ArrayAdapter<String>
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "Kotlin"
      listView = findViewById(R.id.listView)
      editText = findViewById(R.id.editText)
      button = findViewById(R.id.btnAdd)
      arrayAdapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, list)
      button.setOnClickListener {
         list.add(editText.text.toString())
         editText.setText("")
         arrayAdapter.notifyDataSetChanged()
         listView.adapter = arrayAdapter
      }
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.com.kotlipapp">
   <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>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Click here to download the project code.

raja
Published on 21-Apr-2020 08:44:37
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