How to pass a String from one Activity to another Activity in Android using Kotlin?

This example demonstrates how to pass a String from one Activity to another Activity 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"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:id="@+id/relativeLayout"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <Button
      android:id="@+id/newActivityBtn"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_centerVertical="true"
      android:text="Pass message to New Activity" />
   <EditText
      android:id="@+id/etMessage"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_above="@+id/newActivityBtn"
      android:layout_alignParentStart="true"
      android:layout_alignParentEnd="true" />
</RelativeLayout>

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

import android.content.Intent
import android.os.Bundle
import android.widget.Button
import android.widget.EditText
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   lateinit var changeActivityButton: Button
   lateinit var messageEditText: EditText
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      messageEditText = findViewById(R.id.etMessage)
      changeActivityButton = findViewById(R.id.newActivityBtn)
      changeActivityButton.setOnClickListener {
         val intent = Intent(this@MainActivity, NewActivity::class.java)
         val message = messageEditText.text.toString()
         intent.putExtra("message_key", message)
         startActivity(intent)
      }
   }
}

Step 4 − Create a new activity and add the following code −

NewActivity.kt

import android.os.Bundle
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class NewActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_new)
      title = "KotlinApp"
      val message = intent.getStringExtra("message_key")
      val messageTextView: TextView = findViewById(R.id.textView)
      messageTextView.text = message
   }
}

activity_new.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:id="@+id/relativeLayout"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/text2"
      android:layout_centerInParent="true"
      android:layout_marginTop="50dp"
      android:text="New Activity"
      android:textColor="@android:color/holo_red_light"
      android:textStyle="bold" />
   <TextView
      android:id="@+id/textView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:layout_centerHorizontal="true"
      android:text="New Text"
      android:textColor="@android:color/holo_orange_dark"
      android:textSize="32sp"
      android:textStyle="bold|italic" />
</RelativeLayout>

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.