Why state drives UI updates in Android Kotlin - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a mutable state variable in Jetpack Compose.

Android Kotlin

var count by remember { mutableStateOf([1]) }

Drag options to blanks, or click blank then click option'

Anull

B"count"

C0

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a number as initial value

Setting initial value to null

The initial value of the state variable count should be 0 to represent a starting count.

2fill in blank

medium

Complete the code to update the state variable when the button is clicked.

Android Kotlin

Button(onClick = { count [1] count + 1 }) { Text("Click me") }

Drag options to blanks, or click blank then click option'

A+=

B=

C-=

D*=

Attempts:

3 left

💡 Hint

Common Mistakes

Using += which is not supported for state variables

Using wrong operators like -= or *=

To update the state variable count, assign it a new value using =. The expression count + 1 increases the count by one.

3fill in blank

hard

Fix the error in the code to display the current count value in the UI.

Android Kotlin

Text(text = "Count: [1]")

Drag options to blanks, or click blank then click option'

A"count"

Bcount()

Ccount.value

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses like a function call

Using .value which is not needed here

The state variable count can be used directly to show its current value. Using count() or count.value is incorrect here.

4fill in blank

hard

Fill both blanks to create a state variable and update it on button click.

Android Kotlin

var clicks by remember { mutableStateOf([1]) }
Button(onClick = { clicks [2] clicks + 1 }) { Text("Tap") }

Drag options to blanks, or click blank then click option'

A0

B=

C+=

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using += instead of = for state update

Starting state with 1 instead of 0

The state variable clicks starts at 0. To update it, assign the new value with =.

5fill in blank

hard

Fill all three blanks to create a state, display it, and update on button click.

Android Kotlin

var score by remember { mutableStateOf([1]) }
Text(text = "Score: [2]")
Button(onClick = { score [3] score + 5 }) { Text("Add 5") }

Drag options to blanks, or click blank then click option'

A0

Bscore

C=

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using 5 as initial value

Displaying "score" as string instead of variable

Using += instead of = for update

Initialize score with 0. Display it directly. Update it by assigning score + 5 using =.