How to pass data between Activities on an Android application using Kotlin?

This example demonstrates how to pass data between Activities on an Android application 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.

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.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   private val myRequestCode = 1
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      val button: Button = findViewById(R.id.btnPassData)
      button.setOnClickListener {
         val intent = Intent(this, SecondActivity::class.java)
         intent.putExtra(
            "message",
            "Hi, there.."
         )
         startActivity(intent)
      }
      val passDataBack: Button = findViewById(R.id.btnReturnData)
      passDataBack.setOnClickListener {
         val intent = Intent(this, SecondActivity::class.java)
         intent.putExtra("message", "How are you?")
         startActivityForResult(intent, myRequestCode)
      }
   }
   override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
      super.onActivityResult(requestCode, resultCode, data)
      when (requestCode) {
         myRequestCode -> {
            val textView: TextView = findViewById(R.id.resultDataTextView)
            if (resultCode == RESULT_OK) {
               val messageReturn = data!!.getStringExtra("messageReturn")
               textView.text = messageReturn
            }
         }
      }
   }
}

Step 4 − Create a new empty Activity and add the following code −

activity_second.xml

SecondActivity.kt

import android.content.Intent
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class SecondActivity : AppCompatActivity() {
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_second)
      title = "KotlinApp"
      val intent = intent
      val message = intent.getStringExtra("message")
      val textView: TextView = findViewById(R.id.tvReturnData)
      textView.text = message
      val passDataTargetReturnDataButton: Button = findViewById(R.id.btnReturnData)
      passDataTargetReturnDataButton.setOnClickListener {
         val intent = Intent()
         intent.putExtra(
            "messageReturn",
            "Doing good."
         )
         setResult(RESULT_OK, intent)
         finish()
      }
   }
   override fun onBackPressed() {
      val intent = Intent()
      intent.putExtra(
         "messageReturn",
         "You too have a nice day."
      )
      setResult(RESULT_OK, intent)
      finish()
   }
}

Step 5 − Add the following code to androidManifest.xml

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.