How to send a variable from Activity to Fragment in Android using Kotlin?

This example demonstrates how to send a variable from Activity to Fragment in Android using 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"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:gravity="center"    android:orientation="vertical"    android:padding="2dp"    tools:context=".MainActivity">    <EditText       android:id="@+id/editText"       android:layout_width="match_parent"       android:layout_height="wrap_content"       android:layout_marginTop="20sp"       android:hint="ENTER YOUR MESSAGE" />    <Button       android:id="@+id/btnSendData"       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:text="Send data" />    <FrameLayout       android:id="@+id/frameLayout"       android:layout_width="match_parent"       android:layout_height="match_parent">    </FrameLayout> </LinearLayout>

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

import android.os.Bundle import android.widget.Button import android.widget.EditText import androidx.appcompat.app.AppCompatActivity import androidx.fragment.app.FragmentManager import androidx.fragment.app.FragmentTransaction class MainActivity : AppCompatActivity() {    lateinit var editText: EditText    lateinit var button: Button    override fun onCreate(savedInstanceState: Bundle?) {       super.onCreate(savedInstanceState)       setContentView(R.layout.activity_main)       title = "KotlinApp"       val fragmentManager: FragmentManager = supportFragmentManager       val fragmentTransaction: FragmentTransaction = fragmentManager.beginTransaction()       val myFragment = MyFragment()       button = findViewById(R.id.btnSendData)       editText = findViewById(R.id.editText)       button.setOnClickListener {          val bundle = Bundle()          bundle.putString("message", editText.text.toString())          myFragment.arguments = bundle          fragmentTransaction.add(R.id.frameLayout, myFragment).commit()       }    } }

Step 4 − Create a new Blank Fragment and add the following codes

MyFragment.kt

import android.os.Bundle import android.view.LayoutInflater import android.view.View import android.view.ViewGroup import android.widget.TextView import androidx.fragment.app.Fragment class MyFragment : Fragment() {    private lateinit var textView:TextView    override fun onCreateView(       inflater: LayoutInflater, container: ViewGroup?,       savedInstanceState: Bundle?    ): View? {       val view: View = inflater.inflate(R.layout.fragment_my, container, false)       textView = view.findViewById<View>(R.id.textView) as TextView       val bundle = arguments       val message = bundle!!.getString("message")       textView.text = message       return view    } }

fragment_my.xml

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:gravity="center"    android:padding="4dp">    <TextView       android:id="@+id/textView"       android:layout_width="match_parent"       android:layout_height="match_parent"       android:textColor="@android:color/holo_orange_dark"       android:textSize="36sp"       android:textStyle="bold" /> </LinearLayout>

Step 5 − 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="com.example.q11">    <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.