MessageActivity.kt

class MessageActivity : AppCompatActivity() {
    .......
  
    /**
     * launched via onClick in the XML
     * sets this finishing activity's result to the text string
     * entered by the user
     */
    fun onSubmitMessage(view: View) {
        val result = Intent().putExtra(MessageContract.MESSAGE,
            mBinding.messageInput.text.toString())
        setResult(Activity.RESULT_OK, result)
        finish()
    }
  
  .......
}