Stop the Double-Tap! Mastering Stateful Modifiers with Modifier.composed in Jetpack Compose

 Learn how to build reusable, debounced click listeners and stateful UI logic using the power of Modifier.composed.

Stop the Double-Tap! Mastering Stateful Modifiers with Modifier.composed in Jetpack Compose

Have you ever had an app glitch because you clicked a “Submit” button too fast? Or maybe you ended up with three identical screens on your navigation stack because of a “happy finger”?

In Jetpack Compose, we usually build UI logic using simple Modifier extension functions. But what happens when your Modifier needs to remember something? Standard extension functions are stateless. That’s where Modifier.composed enters the room.

The Problem: The “Ghost” Double-Click

Standard modifiers are stateless. If you want a button to ignore rapid-fire clicks (debouncing), you need to track the time of the last click. However, if you try to use remember inside a standard extension function, the compiler will throw an error.

Standard Modifiers = Stateless Composed Modifiers = Stateful

The Solution: Modifier.composed

Modifier.composed allows you to inject Composable behavior—like state, side effects, and animation APIs—into a Modifier. This ensures that every time the modifier is applied to a UI element, it creates its own unique, "remembered" instance of that state.

Implementation: The clickThrottle Modifier

Let’s look at a refined, production-ready version of a debounced click listener.

import androidx.compose.runtime.*
import androidx.compose.ui.Modifier
import androidx.compose.ui.composed
import androidx.compose.ui.platform.debugInspectorInfo

/**
 * A custom modifier that prevents multiple clicks within a specific timeframe.
 * @param interval The lockout period in milliseconds.
 * @param onClick The action to perform if the click is valid.
 */
fun Modifier.clickThrottle(
    interval: Long = 500L,
    onClick: () -> Unit
): Modifier = composed(
    // Helps the Layout Inspector show our custom properties
    inspectorInfo = debugInspectorInfo {
        name = "clickThrottle"
        properties["interval"] = interval
    }
) {
    // Each UI element using this modifier gets its own isolated state
    var lastClickTime by remember { mutableLongStateOf(0L) }

    this.then(
        Modifier.clickable {
            val currentTime = System.currentTimeMillis()
            
            // Only fire if the elapsed time exceeds our interval
            if (currentTime - lastClickTime > interval) {
                lastClickTime = currentTime
                onClick()
            }
        }
    )
}

Why this works:

  • State Isolation: If you have five buttons on a screen, each button tracks its own lastClickTime. Button A won't block Button B.
  • Encapsulation: The UI doesn’t need to know how the debouncing works; it just calls the modifier.
  • Semantic Friendly: By chaining Modifier.clickable, we keep the accessibility and ripple behavior intact.

Beyond Clicks: An “Animated Hover” Example

You can also use composed for animations. Imagine a modifier that makes a component shrink slightly when pressed to give tactile feedback.

fun Modifier.bounceOnClick(): Modifier = composed {
    var isPressed by remember { mutableStateOf(false) }
    // Animate the scale based on the press state
    val scale by animateFloatAsState(
        targetValue = if (isPressed) 0.92f else 1f, 
        label = "bounceAnimation"
    )

    this
        .graphicsLayer(scaleX = scale, scaleY = scale)
        .pointerInput(Unit) {
            awaitPointerEventScope {
                while (true) {
                    val event = awaitPointerEvent()
                    // Logic to update isPressed based on touch events
                    // (Simplified for brevity)
                }
            }
        }
}

⚠️ A Note on Performance

While Modifier.composed is powerful, it isn't "free." Because it introduces an additional composition node for every element it's applied to, it adds a small amount of recomposition overhead.

The Golden Rule: * Use standard extension functions for stateless logic (e.g., padding, background).

  • Use Modifier.composed when you need memory or side effects.
  • For high-performance library development, look into the newer Modifier.Node API, which avoids composition overhead but requires more boilerplate code.

🙋‍♂️ Frequently Asked Questions (FAQs)

Can I use remember in a regular Modifier extension?

No. remember is a Composable function. It can only be called from within a Composable scope, which Modifier.composed provides.

Is state shared across different buttons?

No. Each time you apply the modifier to a Composable, a fresh state instance is created for that specific node.

Why not just handle the timer in the ViewModel?

While you could, handling it in a Modifier makes the behavior reusable. You don’t want to copy-paste timer logic into every ViewModel in your app!

Community Discussion

I’d love to hear how you’re keeping your Compose code clean!

  • Have you ever faced “double-navigation” bugs in your apps?
  • What other stateful modifiers have you built (e.g., visibility trackers, pulse effects)?
  • Do you prefer Modifier.composed or have you made the jump to Modifier.Node?

Let me know in the comments below! 👇

📘 Master Your Next Technical Interview

Since Java is the foundation of Android development, mastering DSA is essential. I highly recommend “Mastering Data Structures & Algorithms in Java”. It’s a focused roadmap covering 100+ coding challenges to help you ace your technical rounds.


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