ui with Jetpack Compose

MainActivity.kt

        val scrollState = rememberScrollState()
        val scope = rememberCoroutineScope()
        var selectedAnimal by remember { mutableStateOf<Animal?>(null) }

        Column(
            modifier = Modifier
                .fillMaxSize()
                .verticalScroll(scrollState),
            verticalArrangement = Arrangement.spacedBy(20.dp),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            Text(
                text = "Hello Compose",
                style = MaterialTheme.typography.h2,
                textAlign = TextAlign.Center,
                modifier = Modifier
                    .fillMaxWidth()
                    .padding(horizontal = 24.dp)
            )

            Image(
                painter = painterResource(
                    id = selectedAnimal?.imageSrc ?: R.drawable.ic_launcher_foreground
                ),
                contentDescription = "selected animal image",
                modifier = Modifier
                    .fillMaxWidth(fraction = 0.75f)
                    .aspectRatio(3 / 8f),
                contentScale = ContentScale.Crop
            )

            Row(
                modifier = Modifier
                    .fillMaxWidth()
                    .wrapContentHeight(),
                horizontalArrangement = Arrangement.SpaceEvenly
            ) {

                RadioButton(
                    selected = selectedAnimal is Animal.Dog,
                    onClick = { selectedAnimal = Animal.Dog },
                )

                RadioButton(
                    selected = selectedAnimal is Animal.Cat,
                    onClick = { selectedAnimal = Animal.Cat },
                )
            }

            Button(
                onClick = {
                    scope.launch {
                        scrollState.animateScrollTo(0)
                    }
                },
                colors = ButtonDefaults.buttonColors(
                    backgroundColor = Color.Black,
                    contentColor = Color.White,
                )
            ) {
                Text(text = "Scroll to Top")
            }

            Spacer(modifier = Modifier.size(100.dp))
        }