Mastering Jetpack Compose: Essential UI Elements and Best Practices for Android Developers

Jetpack Compose is a modern, fully declarative UI framework for building Android applications. It simplifies UI development with its rich set of composable functions, there are nuances and best practices that developers might not be aware of. In this blog, we’ll explore essential Jetpack Compose UI elements, along with practical code snippets, do’s and don’ts, and best practices that will help you write clean, efficient, and maintainable code.

1. Text

The Text composable is one of the most fundamental UI elements in Compose. It displays text content within your UI.

Code Snippet:

Text(
    text = "Hello, Jetpack Compose!",
    style = MaterialTheme.typography.h6,
    modifier = Modifier.padding(16.dp)
)

Do’s:

• Use themes for styling: Leverage MaterialTheme.typography to ensure consistent text styles across your app.

• Prefer StringRes over hardcoded strings: Always use string resources for localization support.

Text(text = stringResource(id = R.string.welcome_message))

Don’ts:

• Avoid hardcoded padding: Hardcoding padding like modifier = Modifier.padding(8.dp) can lead to inconsistencies in your app. Instead, prefer using style resources for consistency.

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2. Button

Buttons are used for user interactions and triggering actions.

Code Snippet:

Button(onClick = { /* Handle click action */ }) {
    Text("Click Me")
}

Do’s:

• Use Button composable with a clear label: Make sure the button’s purpose is obvious by using descriptive text.

Button(onClick = { onConfirmAction() }) {
    Text("Confirm")
}

• Apply content scale: For large buttons, use contentScale to adjust the button’s text scaling.

Don’ts:

• Don’t overuse buttons: Excessive use of buttons in your UI can confuse users. Use them sparingly and only when necessary.

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3. LazyColumn and LazyRow

LazyColumn and LazyRow are optimized list containers in Compose for rendering large or dynamic lists of items efficiently.

Code Snippet (LazyColumn):

LazyColumn(
    modifier = Modifier.fillMaxSize()
) {
    items(listOf("Item 1", "Item 2", "Item 3")) { item ->
        Text(text = item, modifier = Modifier.padding(16.dp))
    }
}

Do’s:

• Use LazyColumn and LazyRow for large lists: These composables load items lazily, meaning they only render the items that are visible, which enhances performance.

• Make use of items function for list rendering: It is the most efficient and declarative way to handle lists.

Don’ts:

• Avoid using Column and Row for large datasets: These will render all items in memory at once, leading to performance issues with long lists.

---

4. Scaffold

Scaffold provides a basic layout structure for your app, including a TopAppBar, BottomBar, and FloatingActionButton.

Code Snippet:

Scaffold(
    topBar = {
        TopAppBar(
            title = { Text("Scaffold Example") }
        )
    },
    floatingActionButton = {
        FloatingActionButton(onClick = { /* Handle click */ }) {
            Icon(Icons.Filled.Add, contentDescription = "Add")
        }
    },
    content = { paddingValues ->
        Column(modifier = Modifier.padding(paddingValues)) {
            Text("Hello, Scaffold!")
        }
    }
)

Do’s:

• Use Scaffold to manage app layout: It helps in defining a consistent app structure, especially for standard UI components like the AppBar and BottomBar.

• Pass the paddingValues to child composables: When using Scaffold, always pass paddingValues to the content to ensure proper insets.

Don’ts:

• Don’t nest multiple Scaffold composables: It’s unnecessary and can cause unexpected UI behavior. Only one Scaffold per screen is needed.

---

5. State Management (remember and mutableStateOf)

State management is essential in Jetpack Compose. remember and mutableStateOf are used to store and modify state locally within composables.

Code Snippet:

@Composable
fun Counter() {
    var count by remember { mutableStateOf(0) }

    Column(
        horizontalAlignment = Alignment.CenterHorizontally,
        verticalArrangement = Arrangement.Center,
        modifier = Modifier.fillMaxSize()
    ) {
        Text("Count: $count")
        Button(onClick = { count++ }) {
            Text("Increment")
        }
    }
}

Do’s:

• Use remember to store state within composables: This ensures the state survives recompositions.

• Use mutableStateOf for basic state types: It’s suitable for primitive types or simple objects.

Don’ts:

• Don’t overuse remember: If your state needs to persist across the screen or app lifecycle, use ViewModel or StateFlow/LiveData instead.

• Avoid using mutable state for UI actions: For complex UI behaviors (like network calls), manage state outside the composable, like in a ViewModel.

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6. Modifier

Modifiers are used to decorate composables, such as adding padding, alignment, and size adjustments.

Code Snippet:

Box(
    modifier = Modifier
        .fillMaxSize()
        .padding(16.dp)
        .background(Color.Gray)
) {
    Text("Modified Box", modifier = Modifier.align(Alignment.Center))
}

Do’s:

• Chain modifiers efficiently: Compose allows you to chain multiple modifiers, so use them to compose complex UI states.

Box(
    modifier = Modifier.fillMaxSize().padding(16.dp).background(Color.Gray)
)

• Use fillMaxWidth() and fillMaxHeight() over fillMaxSize() for better performance when you only need one dimension.

Don’ts:

• Avoid redundant modifiers: Applying the same modifier multiple times can harm performance. For example, don’t use both padding(8.dp) and padding(16.dp) for the same composable.

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7. Custom Composables

Creating custom composables helps keep your code modular and reusable.

Code Snippet:

@Composable
fun CustomCard(title: String, content: String) {
    Card(
        modifier = Modifier.padding(16.dp),
        elevation = 4.dp
    ) {
        Column(modifier = Modifier.padding(16.dp)) {
            Text(text = title, style = MaterialTheme.typography.h6)
            Spacer(modifier = Modifier.height(8.dp))
            Text(text = content)
        }
    }
}

Do’s:

• Break down complex UIs into smaller, reusable composables: This promotes modularity and easier testing.

• Use parameters and default values for customization: Allow composables to be flexible by accepting parameters.

Don’ts:

• Don’t make composables too generic: Overly generalized composables can lead to maintenance problems. Keep them domain-specific for better clarity.

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Animation In Jetpack Compose

1. AnimatedVisibility — AnimatedVisibility is a powerful composable that helps animate the visibility of a composable. It can animate an element’s entrance or exit, adding smooth transitions between states.
   • fadeIn() and fadeOut() are animation specs that control the opacity change during entry and exit.
   • tween() defines the animation’s duration and easing functions.

Code Snippet:

var visible by remember { mutableStateOf(true) }

AnimatedVisibility(
    visible = visible,
    enter = fadeIn(tween(durationMillis = 1000)),
    exit = fadeOut(tween(durationMillis = 1000))
) {
    Text("Hello, Jetpack Compose!", modifier = Modifier.padding(16.dp))
}

Button(onClick = { visible = !visible }) {
    Text("Toggle Visibility")
}

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2. AnimatedContent

AnimatedContent provides a way to animate between different content states when they change. It’s useful for transitions that need to animate between composable states like text, images, or buttons.

• AnimatedContent listens for changes in the targetState and applies animations when the content changes.
• The transition specification uses fadeIn() and fadeOut() for smooth state transitions.

Code Snippet:

var currentContent by remember { mutableStateOf("Initial State") }

AnimatedContent(
    targetState = currentContent,
    transitionSpec = {
        fadeIn() with fadeOut()
    }
) { targetState ->
    Text(targetState, style = MaterialTheme.typography.h6)
}

Button(onClick = { currentContent = "Updated State" }) {
    Text("Change State")
}

---

3. animateDpAsState
**For animating dimensions like padding, size, or position, animateDpAsState is a simple and effective way to smoothly transition between different values.

• animateDpAsState animates changes in the offset value smoothly.
• The targetValue defines the final destination, and Compose handles the animation for you.

Code Snippet:

var offset by remember { mutableStateOf(0.dp) }

val animatedOffset by animateDpAsState(targetValue = offset)

Box(
    modifier = Modifier
        .fillMaxSize()
        .padding(animatedOffset)
) {
    Button(onClick = { offset = if (offset == 0.dp) 200.dp else 0.dp }) {
        Text("Move Me")
    }
}

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4. Gesture-based Animations (Drag)

Jetpack Compose allows animations that are based on user gestures like dragging, scaling, or rotation. You can animate composables based on user interaction using *Modifier.pointerInput.
*• The detectTransformGestures function listens for drag gestures, and the composable’s position is updated in real time.
• You can animate based on the change in the user’s drag movement by adjusting the offsetX and offsetY.

Code Snippet:

var offsetX by remember { mutableStateOf(0f) }
var offsetY by remember { mutableStateOf(0f) }

Box(
    modifier = Modifier
        .fillMaxSize()
        .pointerInput(Unit) {
            detectTransformGestures { _, pan, zoom, _ ->
                offsetX += pan.x
                offsetY += pan.y
            }
        }
) {
    Box(
        modifier = Modifier
            .offset { IntOffset(offsetX.roundToInt(), offsetY.roundToInt()) }
            .size(100.dp)
            .background(Color.Red)
    )
}

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Conclusion :
Jetpack Compose offers powerful and flexible tools for UI development, but developers need to understand and implement best practices for efficient, clean, and maintainable code. From choosing the right UI elements, such as LazyColumn for lists, to managing state correctly with remember and mutableStateOf, these practices will help you build high-quality apps. By adhering to these do’s and don’ts, you’ll be well on your way to mastering Jetpack Compose in your Android projects!

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Jetpack Compose’s animation framework is versatile and allows developers to create smooth, interactive, and visually appealing user experiences. By following the do’s and don’ts, you can leverage Compose’s built-in animation tools for clean, optimized, and meaningful animations. Whether you are animating visibility, state changes, or gesture-based interactions, Compose makes it easy to implement rich animations while maintaining excellent performance and readability in your code.

Jetpack Compose provides a powerful, flexible toolkit for creating modern, dynamic UIs in Android apps. By following best practices and leveraging the right UI elements and animations, developers can build smooth, engaging user experiences. With Compose’s intuitive design, you can easily optimize performance and create aesthetically pleasing, responsive interfaces.