ListView.separated in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a ListView with separators using ListView.separated.

Flutter

ListView.separated(
  itemCount: 5,
  itemBuilder: (context, index) {
    return Text('Item $index');
  },
  separatorBuilder: (context, index) => [1],
)

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

ADivider()

BContainer()

CSizedBox()

DText('sep')

Attempts:

3 left

💡 Hint

Common Mistakes

Using Container() without size or color shows nothing.

Using SizedBox() without height shows no visible separator.

The separatorBuilder requires a widget to separate items. Divider() is the standard separator widget.

2fill in blank

medium

Complete the code to set the number of items in the ListView.separated.

Flutter

ListView.separated(
  itemCount: [1],
  itemBuilder: (context, index) => Text('Item $index'),
  separatorBuilder: (context, index) => Divider(),
)

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

A10

B0

C5

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Setting itemCount to 0 shows no items.

Negative itemCount causes errors.

itemCount must be a positive integer representing how many items to show. 5 means 5 items.

3fill in blank

hard

Fix the error in the separatorBuilder to properly return a widget.

Flutter

ListView.separated(
  itemCount: 3,
  itemBuilder: (context, index) => Text('Item $index'),
  separatorBuilder: (context, index) [1] Divider(),
)

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

A{ return

B=>

C:

D=

Attempts:

3 left

💡 Hint

Common Mistakes

Using ':' causes syntax errors.

Using '=' alone is invalid for function body.

separatorBuilder is a function that returns a widget. Using '=>' returns the Divider() widget correctly.

4fill in blank

hard

Fill both blanks to create a ListView.separated with 4 items and a blue divider.

Flutter

ListView.separated(
  itemCount: [1],
  itemBuilder: (context, index) => Text('Item $index'),
  separatorBuilder: (context, index) => Divider(color: [2]),
)

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

A4

B5

CColors.blue

DColors.red

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong color like Colors.red when blue is asked.

Setting itemCount to 5 shows one extra item.

itemCount is 4 to show four items. Divider color is set to Colors.blue for a blue line.

5fill in blank

hard

Fill all three blanks to create a ListView.separated with 3 items, a green divider, and item text showing index + 1.

Flutter

ListView.separated(
  itemCount: [1],
  itemBuilder: (context, index) => Text('Item $[2]'),
  separatorBuilder: (context, index) => Divider(color: [3]),
)

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

A3

Bindex + 1

CColors.green

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'index' shows zero-based numbering starting at 0.

Using wrong color like Colors.red instead of green.

itemCount is 3 for three items. Text shows index + 1 to start counting from 1. Divider color is green.

Practice

1. What is the main purpose of using ListView.separated in Flutter?

easy

A. To display a single static widget

B. To create a grid layout with fixed columns

C. To create a scrollable list with separators between items

D. To handle user input forms

Solution

1. Step 1: Understand ListView.separated usage

   ListView.separated is designed to build lists with separators between each item.

2. Step 2: Compare with other options

   Options B, C, and D describe other Flutter widgets or uses unrelated to ListView.separated.

3. Final Answer:

   To create a scrollable list with separators between items -> Option C

4. Quick Check:

   ListView.separated = scrollable list with separators [OK]

Hint: Remember: separated means items with dividers [OK]

Common Mistakes:

• Confusing ListView.separated with GridView
• Thinking it creates static widgets
• Assuming it handles user input

2. Which of the following is the correct syntax to create a ListView.separated with 5 items?

easy

A. ListView.separated(itemCount: 5, itemBuilder: (context, index) => Text('Item $index'), separatorBuilder: (context, index) => Divider())

B. ListView.separated(items: 5, buildItem: (i) => Text('Item $i'), buildSeparator: () => Divider())

C. ListView.separated(count: 5, builder: (context, i) => Text('Item $i'), separator: Divider())

D. ListView.separated(length: 5, item: (context, i) => Text('Item $i'), separatorBuilder: () => Divider())

Solution

1. Step 1: Identify correct parameter names

   The correct parameters are itemCount, itemBuilder, and separatorBuilder.

2. Step 2: Check function signatures

   itemBuilder and separatorBuilder take (context, index) and return widgets.

3. Final Answer:

   ListView.separated(itemCount: 5, itemBuilder: (context, index) => Text('Item $index'), separatorBuilder: (context, index) => Divider()) -> Option A

4. Quick Check:

   Correct parameter names and builder signatures = ListView.separated(itemCount: 5, itemBuilder: (context, index) => Text('Item $index'), separatorBuilder: (context, index) => Divider()) [OK]

Hint: Use itemCount, itemBuilder, separatorBuilder exactly [OK]

Common Mistakes:

• Using wrong parameter names like items or count
• Omitting context or index in builder functions
• Passing widgets directly instead of builder functions

3. What will be the output of this Flutter code snippet?

ListView.separated(
  itemCount: 3,
  itemBuilder: (context, index) => Text('Item $index'),
  separatorBuilder: (context, index) => Divider(color: Colors.red),
)

medium

A. A list with 4 items including dividers as text

B. A scrollable list with 3 items and red dividers between them

C. A scrollable list with 3 items but no dividers

D. Compilation error due to missing separator widget

Solution

1. Step 1: Analyze itemCount and itemBuilder

   There are 3 items labeled 'Item 0', 'Item 1', and 'Item 2'.

2. Step 2: Analyze separatorBuilder

   Between each item, a red colored Divider widget is inserted.

3. Final Answer:

   A scrollable list with 3 items and red dividers between them -> Option B

4. Quick Check:

   itemCount=3 with red Dividers = A scrollable list with 3 items and red dividers between them [OK]

Hint: Separators appear between items, not as extra items [OK]

Common Mistakes:

• Thinking separators add extra list items
• Ignoring the color property of Divider
• Assuming no separators appear without extra code

4. Identify the error in this ListView.separated code:

ListView.separated(
  itemCount: 3,
  itemBuilder: (context) => Text('Item'),
  separatorBuilder: (context, index) => Divider(),
)

medium

A. itemBuilder missing index parameter

B. separatorBuilder missing context parameter

C. itemCount should be inside itemBuilder

D. Divider widget cannot be used as separator

Solution

1. Step 1: Check itemBuilder function signature

   itemBuilder must have two parameters: (context, index). Here it only has (context).

2. Step 2: Verify separatorBuilder signature

   separatorBuilder correctly has (context, index).

3. Final Answer:

   itemBuilder missing index parameter -> Option A

4. Quick Check:

   itemBuilder requires (context, index) parameters [OK]

Hint: itemBuilder always needs context and index [OK]

Common Mistakes:

• Omitting index in itemBuilder
• Confusing separatorBuilder parameters
• Thinking Divider can't be separator

5. You want to create a ListView.separated that shows a list of names but only adds a separator if the next name starts with a different first letter. Which approach is correct?

hard

A. Add all separators unconditionally between items

B. Use a GridView instead of ListView.separated

C. Use itemBuilder to insert Divider widgets manually between items

D. Use separatorBuilder to compare current and next item first letters and return Divider or SizedBox.shrink() accordingly

Solution

1. Step 1: Understand conditional separators

   To add separators only when the next item's first letter differs, separatorBuilder must check adjacent items.

2. Step 2: Implement conditional logic in separatorBuilder

   Return a Divider if letters differ; otherwise, return SizedBox.shrink() to show no separator.

3. Final Answer:

   Use separatorBuilder to compare current and next item first letters and return Divider or SizedBox.shrink() accordingly -> Option D

4. Quick Check:

   Conditional separator logic belongs in separatorBuilder [OK]

Hint: Use separatorBuilder to conditionally show dividers [OK]

Common Mistakes:

• Adding separators unconditionally
• Inserting Dividers inside itemBuilder
• Using GridView which lacks separators