Synthetics.kt

package com.example
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

//        val textEmail: TextView = findViewById(R.id.txt_email)
//        textEmail.text = "someone@gmail.com"

        textEmail.text = "someone@gmail.com"
    }
}