LazyColumn for lists in Android Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What will this LazyColumn display?

Given the following Kotlin Compose code, what will the LazyColumn show on the screen?

Android Kotlin

LazyColumn {
  items(listOf("Apple", "Banana", "Cherry")) { fruit ->
    Text(text = fruit)
  }
}

A A horizontal list showing the words: Apple, Banana, Cherry

B A vertical list showing the words: Apple, Banana, Cherry

C A vertical list showing numbers 0, 1, 2

D An empty screen with no text

💡 Hint

LazyColumn creates a vertical scrolling list. The items function shows each element.

LazyColumn displays items vertically. Here, it shows each fruit name as a Text item.

📝 Syntax

intermediate

Identify the syntax error in this LazyColumn code

Which option correctly fixes the syntax error in this LazyColumn snippet?

Android Kotlin

LazyColumn {
  items(5) { index ->
    Text(index)
  }
}

A Change Text(index) to Text(text = "Item $index")

B Add a comma after items(5), like items(5,)

C Change items(5) to items(count = 5)

D Replace LazyColumn with Column

💡 Hint

Text composable requires the text parameter name or a single string argument.

Text composable expects a named parameter text or a single string argument. Text(index) passes an Int instead of String, causing a type mismatch.

❓ lifecycle

advanced

What happens when the list data changes in LazyColumn?

If the list passed to LazyColumn changes, how does the UI behave?

Android Kotlin

var fruits by remember { mutableStateOf(listOf("Apple", "Banana")) }
LazyColumn {
  items(fruits) { fruit ->
    Text(text = fruit)
  }
}
// Later fruits = listOf("Apple", "Banana", "Cherry")

A LazyColumn shows the old list and ignores the change

B LazyColumn clears all items and shows nothing

C App crashes due to list mutation

D LazyColumn automatically updates to show the new list with Cherry added

💡 Hint

Jetpack Compose tracks state changes and recomposes UI automatically.

When the state list changes, Compose recomposes LazyColumn to show the updated items.

❓ navigation

advanced

How to handle item clicks in LazyColumn?

Which code snippet correctly handles a click on each item in LazyColumn to print the clicked item?

Android Kotlin

val fruits = listOf("Apple", "Banana", "Cherry")
LazyColumn {
  items(fruits) { fruit ->
    Text(text = fruit)
  }
}

A Add a click listener to the list variable fruits

B Add onClick parameter to LazyColumn { onClick = { println(fruit) } }

C Wrap Text in Modifier.clickable { println("Clicked: $fruit") }

D Use Button instead of Text without any modifier

💡 Hint

Use Modifier.clickable on the composable you want to be clickable.

Modifier.clickable on Text allows detecting clicks and running code like println.

🔧 Debug

expert

Why does this LazyColumn cause a runtime error?

Examine this code and select the reason for the runtime crash.

Android Kotlin

val fruits = listOf("Apple", "Banana", "Cherry")
LazyColumn {
  items(5) { index ->
    Text(text = fruits[index])
  }
}

A Accessing fruits[index] causes IndexOutOfBoundsException

B Using items(count) with a list requires itemsIndexed or items(list) instead

C LazyColumn cannot use items with a count parameter

D Text composable cannot be used inside LazyColumn

💡 Hint

When using items(count), indices go from 0 to count-1. Check if list supports those indices.

items(5) iterates indices 0 to 4, but fruits has only 3 elements (size=3), so fruits[3] and fruits[4] throw IndexOutOfBoundsException.