After adding the button and alert dialog

MainActivity.kt

package com.death.demo

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.compose.Composable
import androidx.compose.State
import androidx.compose.state
import androidx.compose.unaryPlus
import androidx.ui.core.Text
import androidx.ui.core.setContent
import androidx.ui.layout.Column
import androidx.ui.layout.Container
import androidx.ui.material.AlertDialog
import androidx.ui.material.Button
import androidx.ui.material.MaterialTheme

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            MaterialTheme {
                Column {
                    showAlertButton()
                    presentDialog()
                }
            }
        }
    }

    @Composable
    fun showAlertButton(){
        Button("Show Alert",
                onClick = {

                }
        )
    }


    @Composable
    fun presentDialog() {
            AlertDialog(
                    onCloseRequest = {
                    },
                    title = {
                        Text(text = "Alert Dialog")
                    },
                    text = {
                        Text("JetPack Compose Alert Dialog!")
                    },
                    confirmButton = {
                        Button("Confirm", onClick = {

                        })
                    }
            )
    }
}