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.unaryPlus
import androidx.ui.core.Text
import androidx.ui.core.setContent
import androidx.ui.layout.Column
import androidx.ui.material.AlertDialog
import androidx.ui.material.Button
import androidx.ui.material.MaterialTheme


// Here i created the variable of type State<Boolean> which will be used to
// show/hide the alert dialog
private val showDialog  = +state{
    false
}


class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MaterialTheme {
                Column {
                    showAlertButton()
                    presentDialog()
                }
            }
        }
    }

    @Composable
    fun showAlertButton(){
        Button("Show Alert",
                onClick = {
                    // Here changing the value to true so that the alert dialog can be shown
                    showDialog.value = true
                }
        )
    }


    @Composable
    fun presentDialog() {
        if(showDialog.value)
            AlertDialog(
                    onCloseRequest = {
                        showDialog.value = false
                    },
                    title = {
                        Text(text = "Alert Dialog")
                    },
                    text = {
                        Text("JetPack Compose Alert Dialog!")
                    },
                    confirmButton = {
                        Button("Confirm", onClick = {
                            // reset the value to false, which will make the dialog go away
                            showDialog.value = false
                        })
                    }
            )
    }
}