https://developer.android.google.cn/training/basics/firstapp

MainActivity.kt

package com.example.myfirstapp

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.content.Intent
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {
companion object {
val EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE"
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
fun sendMessage(view: View) {
val message = editText.text.toString()
val intent = Intent(this, DisplayMessageActivity::class.java)
intent.putExtra(EXTRA_MESSAGE, message)
startActivity(intent)
}
}

DisplayMessageActivity.kt

package com.example.myfirstapp

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import kotlinx.android.synthetic.main.activity_display_message.*

class DisplayMessageActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {  
    super.onCreate(savedInstanceState)  
    setContentView(R.layout.activity\_display\_message)

    val message = intent.getStringExtra(MainActivity.EXTRA\_MESSAGE)  
    textView.text=message;  
}  

}