Why this nullpointerexception occured?

class MainActivity : AppCompatActivity() {

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

    val number1 = idOf_editTextnumber1.text.toString()
    val number2 = idOf_editTextnumber2.text.toString()
    idOf_OpeninActvity2.setOnClickListener {
        val newIntentOfOpening = Intent(this, SecondActivity::class.java)
        newIntentOfOpening.putExtra("number1", number1)
        newIntentOfOpening.putExtra("number2", number2)
        startActivityForResult(newIntentOfOpening, 1)
    }
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    if (requestCode == 1){
        if (resultCode == Activity.RESULT_OK){
            val intent3 = Intent()
            val result = intent3.extras?.getString("result")
            idOf_textViewOfResult.text = result
        }
        if (resultCode == Activity.RESULT_CANCELED){
            idOf_textViewOfResult.text = "Nothing selected"
        }
    }

}


The Second Activity:

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

   val intentNew = Intent()
   val number1 = intentNew.getIntExtra("number1",0)
   val number2 = intentNew.getIntExtra("number2",0)
   idOf_ShowingTwoNumbers.text = "Numbers: $number1, $number2"
   idOf_Adding.setOnClickListener {
       val result: Int  = number1 + number2
       val intent2 = Intent()
       intent2.putExtra("result", result)
       setResult(Activity.RESULT_OK, intent2)
       finish()
   }

val number1 = intentNew.extras!!.getString("number1")
val number2 = intentNew.extras!!.getString("number2")

val number1 = intentNew.getIntExtra("number1",0)
val number2 = intentNew.getIntExtra("number2",0)