Create Jetpack Compose Lists with Sticky Headers for Better UX

Lists are a cornerstone of mobile app development, serving as the backbone for countless interfaces, from messaging apps to e-commerce platforms. In Jetpack Compose, the declarative UI toolkit for Android, creating lists has never been easier or more efficient. However, to provide a polished and user-friendly experience, sticky headers can significantly enhance the usability of your lists by providing context as users scroll through large datasets.

In this blog post, we will explore how to implement sticky headers in Jetpack Compose lists, discuss best practices for improving performance, and examine advanced use cases that elevate user experience (UX).

What Are Sticky Headers?

Sticky headers are a UX pattern where certain header elements remain fixed at the top of the list as users scroll through grouped items. For instance, in a contact list organized alphabetically, the current letter stays visible at the top until a new group starts.

Benefits of Sticky Headers:

Context Preservation: Users can quickly identify the current group without losing their place.
Improved Accessibility: Sticky headers can make large datasets more navigable.
Professional Aesthetic: They add polish and intuitiveness to the UI.

Setting Up Your Project

Before diving into sticky headers, ensure your project is ready for Jetpack Compose:

Update Dependencies: Add the latest Jetpack Compose libraries to your build.gradle file:

dependencies {
    implementation "androidx.compose.ui:ui:1.5.0"
    implementation "androidx.compose.foundation:foundation:1.5.0"
    implementation "androidx.compose.material:material:1.5.0"
    implementation "androidx.compose.runtime:runtime:1.5.0"
}

Enable Compose: Ensure Compose is enabled in your build.gradle:

android {
    buildFeatures {
        compose true
    }
    composeOptions {
        kotlinCompilerExtensionVersion '1.5.0'
    }
}

Creating a Basic LazyColumn

LazyColumn is the go-to composable for creating scrollable lists in Jetpack Compose. Let’s start by creating a simple list:

@Composable
fun SimpleList(items: List<String>) {
    LazyColumn {
        items(items) { item ->
            Text(
                text = item,
                modifier = Modifier
                    .fillMaxWidth()
                    .padding(16.dp),
                style = MaterialTheme.typography.body1
            )
        }
    }
}

While this implementation works, it doesn’t handle grouping or sticky headers. Let’s enhance it with those features.

Adding Sticky Headers

Jetpack Compose doesn’t natively support sticky headers out of the box. However, the LazyColumn provides enough flexibility to implement this feature.

Here’s how to create a list with sticky headers:

Grouped Data:

Prepare your data grouped by a category (e.g., letters):

val groupedItems = mapOf(
    "A" to listOf("Apple", "Avocado"),
    "B" to listOf("Banana", "Blueberry"),
    "C" to listOf("Cherry", "Cucumber")
)

Implementing Sticky Headers:

@Composable
fun ListWithStickyHeaders(groupedItems: Map<String, List<String>>) {
    LazyColumn {
        groupedItems.forEach { (header, items) ->
            stickyHeader {
                Text(
                    text = header,
                    modifier = Modifier
                        .fillMaxWidth()
                        .background(Color.Gray)
                        .padding(8.dp),
                    style = MaterialTheme.typography.h6,
                    color = Color.White
                )
            }

            items(items) { item ->
                Text(
                    text = item,
                    modifier = Modifier
                        .fillMaxWidth()
                        .padding(16.dp),
                    style = MaterialTheme.typography.body1
                )
            }
        }
    }
}

In this implementation:

stickyHeader ensures the header remains visible at the top during scrolling.
Each header and its items are iterated using groupedItems.forEach.

Optimizing Performance

When working with large lists, performance can become a concern. Follow these best practices to ensure smooth scrolling:

Use remember for State Management: Cache computations to avoid unnecessary recompositions:
```
val groupedItems by remember { mutableStateOf(sampleGroupedItems()) }
```
Avoid Overdraw: Minimize overlapping views by keeping the UI layout simple and avoiding redundant background or padding.
Asynchronous Data Loading: Use coroutines with LazyListState to handle data pagination seamlessly.
Efficient UI Updates: Leverage LazyColumn diffing to update only the affected items.

Advanced Use Cases

Dynamic Headers:

For scenarios where header content changes based on user actions:

@Composable
fun DynamicStickyHeader(currentGroup: String, items: List<String>) {
    LazyColumn {
        stickyHeader {
            Text(
                text = "Group: $currentGroup",
                modifier = Modifier
                    .fillMaxWidth()
                    .background(Color.DarkGray)
                    .padding(8.dp),
                color = Color.White
            )
        }

        items(items) { item ->
            Text(
                text = item,
                modifier = Modifier.padding(16.dp)
            )
        }
    }
}

Infinite Scrolling with Headers:

Combine sticky headers with infinite scrolling for datasets fetched from a server. Use LazyListState and paging libraries to dynamically load and display grouped data.

Testing and Debugging

When implementing sticky headers, thoroughly test to ensure:

Accessibility: Verify proper navigation with screen readers like TalkBack.
Scroll Behavior: Ensure headers behave predictably during rapid scrolling.
Edge Cases: Test empty groups and datasets with large item counts.

Conclusion

Sticky headers are a powerful tool for improving UX in Jetpack Compose lists. By leveraging LazyColumn and best practices, you can create performant, visually appealing lists that keep users engaged. Whether you’re building contact lists, e-commerce catalogs, or event schedules, sticky headers ensure clarity and polish in your app’s UI.

Start experimenting with sticky headers today, and take your Jetpack Compose skills to the next level!