activity

package com.example.exam

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import androidx.appcompat.widget.ButtonBarLayout
import androidx.core.widget.TextViewCompat
import kotlinx.android.synthetic.main.activity_main.*
import kotlin.system.exitProcess

class MainActivity : AppCompatActivity() , View.OnClickListener{

    private lateinit var edtText : EditText
    private lateinit var btn1 : Button
    private lateinit var btn2 : Button
    private lateinit var txt1 : TextView

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

        edtText.findViewById<EditText>(R.id.edit1)
        btn1.findViewById<Button>(R.id.btn1)
        btn2.findViewById<Button>(R.id.btn2)
        txt1.findViewById<TextView>(R.id.txt1)


    }

    override fun onClick(v: View?) {
        if (v?.id == R.id.btn1) {
            var input = edtText.text.toString().trim()
            txt1.text = "Hasil :" +input
        }

        if (v?.id == R.id.btn2) {
            moveTaskToBack(true)
            exitProcess(-1)
        }
    }
}