How to Implement Press Back Again to Exit in Android using Jetpack Compose?

import androidx.compose.ui.graphics.Color

val Purple200 = Color(0xFF0F9D58)
val Purple500 = Color(0xFF0F9D58)
val Purple700 = Color(0xFF3700B3)
val Teal200 = Color(0xFF03DAC5)

// on below line we are adding different colors.
val greenColor = Color(0xFF0F9D58)

import android.app.Activity
import android.os.Build
import android.os.Bundle
import android.widget.Toast
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.annotation.RequiresApi
import androidx.compose.foundation.layout.*
import androidx.compose.material.*
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import com.example.newcanaryproject.ui.theme.NewCanaryProjectTheme
import com.example.newcanaryproject.ui.theme.greenColor

class MainActivity : ComponentActivity() {
    @RequiresApi(Build.VERSION_CODES.M)
    private var pressedTime: Long = 0

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            NewCanaryProjectTheme {
                // on below line we are specifying background color for our application
                Surface(
                    // on below line we are specifying modifier and color for our app
                    modifier = Modifier.fillMaxSize(), color = MaterialTheme.colors.background
                ) {
                    // on the below line we are specifying the theme as the scaffold.
                    Scaffold(
                        // in scaffold we are specifying the top bar.
                        topBar = {
                            // inside top bar we are specifying background color.
                            TopAppBar(backgroundColor = greenColor,
                                // along with that we are specifying title for our top bar.
                                title = {
                                    // in the top bar we are specifying tile as a text
                                    Text(
                                        // on below line we are specifying
                                        // text to display in top app bar.
                                        text = "GFG",

                                        // on below line we are specifying
                                        // modifier to fill max width.
                                        modifier = Modifier.fillMaxWidth(),

                                        // on below line we are specifying
                                        // text alignment.
                                        textAlign = TextAlign.Center,

                                        // on below line we are specifying
                                        // color for our text.
                                        color = Color.White
                                    )
                                })
                        }) {
                        // on below line we are calling connection information method to display UI
                        pressBackAgainToExit()
                    }
                }
            }
        }
    }

    // on below line we are calling on back press method.
    @RequiresApi(Build.VERSION_CODES.M)
    override fun onBackPressed() {
        // on below line we are checking if the press time is greater than 2 sec
        if (pressedTime + 2000 > System.currentTimeMillis()) {
            // if time is greater than 2 sec we are closing the application.
            super.onBackPressed()
            finish()
        } else {
            // in else condition displaying a toast message.
            Toast.makeText(getBaseContext(), "Press back again to exit", Toast.LENGTH_SHORT).show();
        }
        // on below line initializing our press time variable 
        pressedTime = System.currentTimeMillis();
    }
}

// on below line we are creating contact picker function.
@Composable
fun pressBackAgainToExit() {
    // on below line we are creating variable for activity.
    val activity = LocalContext.current as Activity
    // on below line we are creating a column,
    Column(
        // on below line we are adding a modifier to it,
        modifier = Modifier
            .fillMaxSize()
            // on below line we are adding a padding.
            .padding(all = 30.dp),
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
    ) {
        // on below line we are adding a text for heading.
        Text(
            // on below line we are specifying text
            text = "Press Back Again to Exit in Android",
            // on below line we are specifying text color, font size and font weight
            color = greenColor, fontSize = 20.sp, fontWeight = FontWeight.Bold
        )
    }
}