KlassenKonstantin/MainActivity.kt

## MainActivity.kt
import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.animation.ExperimentalSharedTransitionApi
import androidx.compose.animation.SharedTransitionLayout
import androidx.compose.foundation.background
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.aspectRatio
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.rounded.CheckCircle
import androidx.compose.material3.HorizontalDivider
import androidx.compose.material3.Icon
import androidx.compose.material3.ListItem
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.unit.dp
import de.kuno.disappearingitems.ui.theme.DisappearingItemsTheme
import kotlin.random.Random

@OptIn(ExperimentalSharedTransitionApi::class)
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContent {
            TheTheme {
                SharedTransitionLayout { // Remove this -> no crash
                    var expandedHeaders by remember { mutableStateOf(setOf<String>()) }
                    val items = buildList {
                        repeat(5) { header ->
                            add(Element.Header(header.toString()))
                            if (expandedHeaders.contains(header.toString())) {
                                repeat(100) {
                                    add(Element.Item(header.toString(), it.toString(), Random.nextBoolean()))
                                }
                            }
                            add(Element.Divider("$header-divider"))
                        }
                    }

                    Scaffold(
                        modifier = Modifier.fillMaxSize(),
                        topBar = {
                            Box(modifier = Modifier
                                .fillMaxWidth()
                                .height(100.dp))
                        }
                    ) { innerPadding ->
                        LazyColumn(
                            Modifier.padding(innerPadding)
                        ) {
                            items(items, key = { it.id }, contentType = { it.javaClass.simpleName }) { element ->
                                when (element) {
                                    is Element.Header -> ListItem(
                                        modifier = Modifier
                                            .animateItem()
                                            .clickable {
                                                if (expandedHeaders.contains(element.title)) {
                                                    expandedHeaders = expandedHeaders
                                                        .filter { it != element.title }
                                                        .toSet()
                                                } else {
                                                    expandedHeaders = expandedHeaders + element.title
                                                }
                                            },
                                        headlineContent = { Text(text = "Header ${element.title}") }
                                    )

                                    is Element.Item -> {
                                        Row(
                                            Modifier
                                                .animateItem()
                                                .padding(16.dp)
                                        ) {
                                            Box(
                                                modifier = Modifier
                                                    .padding(16.dp)
                                                    .height(48.dp)
                                                    .aspectRatio(1f, true)
                                                    .background(Color.Red, CircleShape)
                                            ) {
                                                Text(
                                                    modifier = Modifier.align(Alignment.Center),
                                                    text = "A"
                                                )
                                                if (element.hasCheckmark) {
                                                    Box(
                                                        modifier = Modifier
                                                            .align(Alignment.BottomEnd)
                                                            .clip(CircleShape)
                                                            .background(MaterialTheme.colorScheme.surface),
                                                    ) {
                                                        Icon(
                                                            modifier = Modifier.size(16.dp),
                                                            imageVector = Icons.Rounded.CheckCircle,
                                                            contentDescription = null,
                                                        )
                                                    }
                                                }
                                            }
                                            Text(text = element.text)
                                        }
                                    }

                                    is Element.Divider -> {
                                        HorizontalDivider(Modifier.animateItem())
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
}

sealed interface Element {
    val id: String

    data class Header(
        val title: String,
    ) : Element {
        override val id = title
    }

    data class Divider(
        override val id: String,
    ) : Element

    data class Item(
        private val headerId: String,
        val text: String,
        val hasCheckmark: Boolean,
    ) : Element {
        override val id = "$headerId-$text"
    }
}
	import android.os.Bundle
	import androidx.activity.ComponentActivity
	import androidx.activity.compose.setContent
	import androidx.activity.enableEdgeToEdge
	import androidx.compose.animation.ExperimentalSharedTransitionApi
	import androidx.compose.animation.SharedTransitionLayout
	import androidx.compose.foundation.background
	import androidx.compose.foundation.clickable
	import androidx.compose.foundation.layout.Box
	import androidx.compose.foundation.layout.Row
	import androidx.compose.foundation.layout.aspectRatio
	import androidx.compose.foundation.layout.fillMaxSize
	import androidx.compose.foundation.layout.fillMaxWidth
	import androidx.compose.foundation.layout.height
	import androidx.compose.foundation.layout.padding
	import androidx.compose.foundation.layout.size
	import androidx.compose.foundation.lazy.LazyColumn
	import androidx.compose.foundation.lazy.items
	import androidx.compose.foundation.shape.CircleShape
	import androidx.compose.material.icons.Icons
	import androidx.compose.material.icons.rounded.CheckCircle
	import androidx.compose.material3.HorizontalDivider
	import androidx.compose.material3.Icon
	import androidx.compose.material3.ListItem
	import androidx.compose.material3.MaterialTheme
	import androidx.compose.material3.Scaffold
	import androidx.compose.material3.Text
	import androidx.compose.runtime.getValue
	import androidx.compose.runtime.mutableStateOf
	import androidx.compose.runtime.remember
	import androidx.compose.runtime.setValue
	import androidx.compose.ui.Alignment
	import androidx.compose.ui.Modifier
	import androidx.compose.ui.draw.clip
	import androidx.compose.ui.graphics.Color
	import androidx.compose.ui.unit.dp
	import de.kuno.disappearingitems.ui.theme.DisappearingItemsTheme
	import kotlin.random.Random

	@OptIn(ExperimentalSharedTransitionApi::class)
	class MainActivity : ComponentActivity() {
	override fun onCreate(savedInstanceState: Bundle?) {
	super.onCreate(savedInstanceState)
	enableEdgeToEdge()
	setContent {
	TheTheme {
	SharedTransitionLayout { // Remove this -> no crash
	var expandedHeaders by remember { mutableStateOf(setOf<String>()) }
	val items = buildList {
	repeat(5) { header ->
	add(Element.Header(header.toString()))
	if (expandedHeaders.contains(header.toString())) {
	repeat(100) {
	add(Element.Item(header.toString(), it.toString(), Random.nextBoolean()))
	}
	}
	add(Element.Divider("$header-divider"))
	}
	}

	Scaffold(
	modifier = Modifier.fillMaxSize(),
	topBar = {
	Box(modifier = Modifier
	.fillMaxWidth()
	.height(100.dp))
	}
	) { innerPadding ->
	LazyColumn(
	Modifier.padding(innerPadding)
	) {
	items(items, key = { it.id }, contentType = { it.javaClass.simpleName }) { element ->
	when (element) {
	is Element.Header -> ListItem(
	modifier = Modifier
	.animateItem()
	.clickable {
	if (expandedHeaders.contains(element.title)) {
	expandedHeaders = expandedHeaders
	.filter { it != element.title }
	.toSet()
	} else {
	expandedHeaders = expandedHeaders + element.title
	}
	},
	headlineContent = { Text(text = "Header ${element.title}") }
	)

	is Element.Item -> {
	Row(
	Modifier
	.animateItem()
	.padding(16.dp)
	) {
	Box(
	modifier = Modifier
	.padding(16.dp)
	.height(48.dp)
	.aspectRatio(1f, true)
	.background(Color.Red, CircleShape)
	) {
	Text(
	modifier = Modifier.align(Alignment.Center),
	text = "A"
	)
	if (element.hasCheckmark) {
	Box(
	modifier = Modifier
	.align(Alignment.BottomEnd)
	.clip(CircleShape)
	.background(MaterialTheme.colorScheme.surface),
	) {
	Icon(
	modifier = Modifier.size(16.dp),
	imageVector = Icons.Rounded.CheckCircle,
	contentDescription = null,
	)
	}
	}
	}
	Text(text = element.text)
	}
	}

	is Element.Divider -> {
	HorizontalDivider(Modifier.animateItem())
	}
	}
	}
	}
	}
	}
	}
	}
	}
	}

	sealed interface Element {
	val id: String

	data class Header(
	val title: String,
	) : Element {
	override val id = title
	}

	data class Divider(
	override val id: String,
	) : Element

	data class Item(
	private val headerId: String,
	val text: String,
	val hasCheckmark: Boolean,
	) : Element {
	override val id = "$headerId-$text"
	}
	}