Pagination and sorting with Pageable in Spring Boot - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the output of this Pageable request?

Given a Spring Data repository method call with Pageable, what page content is returned?

Spring Boot

Pageable pageable = PageRequest.of(1, 3, Sort.by("name").ascending());
Page<User> page = userRepository.findAll(pageable);
List<User> users = page.getContent();
return users.stream().map(User::getName).toList();

A ["David", "Eve", "Frank"]

B ["Alice", "Bob", "Charlie"]

C ["Grace", "Heidi", "Ivan"]

D ["Jack", "Karl", "Liam"]

💡 Hint

Remember page index starts at 0, and sorting is ascending by name.

The Pageable requests page 1 (second page) with 3 items per page, sorted by name ascending. So the first page (index 0) has the first 3 names alphabetically, the second page has the next 3.

📝 Syntax

intermediate

Which Pageable creation code is correct for descending sort by age?

Choose the correct way to create a Pageable object that requests page 0, 5 items per page, sorted by age descending.

A Pageable pageable = PageRequest.of(0, 5, Sort.descending("age"));

B Pageable pageable = PageRequest.of(0, 5, Sort.by("age").descending());

C Pageable pageable = new Pageable(0, 5, Sort.by("age").desc());

D Pageable pageable = PageRequest.create(0, 5, Sort.by("age").descending());

💡 Hint

Check the official PageRequest factory method and Sort API.

PageRequest.of is the correct factory method. Sort.by("age").descending() creates the descending sort.

❓ state_output

advanced

What is the total number of pages for this Pageable query?

Assuming the database has 23 total items, what is the total number of pages returned by this Pageable query?

Spring Boot

Pageable pageable = PageRequest.of(0, 5);
Page<Item> page = itemRepository.findAll(pageable);
int totalPages = page.getTotalPages();

A 5

B 4

C 7

D 6

💡 Hint

Divide total items by page size and round up.

23 items with 5 per page means 4 pages fully filled (5*4=20) plus 1 page with 3 items, total 5 pages. 23/5 = 4.6, rounded up is 5 pages.

🔧 Debug

advanced

Why does this Pageable query throw an exception?

This code throws an IllegalArgumentException. What is the cause?

Spring Boot

Pageable pageable = PageRequest.of(-1, 10);
Page<Product> page = productRepository.findAll(pageable);

A Repository method findAll does not accept Pageable.

B Page size cannot be 10; must be less than 10.

C Page index cannot be negative; -1 is invalid.

D Sort parameter is missing, causing exception.

💡 Hint

Check the parameters for PageRequest.of.

PageRequest.of requires a non-negative page index. Negative page index causes IllegalArgumentException.

🧠 Conceptual

expert

How does Spring Data handle sorting when multiple Sort.Order objects are provided in Pageable?

If a Pageable is created with Sort.by(Order.asc("name"), Order.desc("age")), how will the sorting be applied?

A Sorts only by the last Order specified, ignoring the first.

B Sorts first by age descending, then by name ascending for items with the same age.

C Throws an exception because multiple Sort.Order objects are not allowed.

D Sorts first by name ascending, then by age descending for items with the same name.

💡 Hint

Think about how multi-level sorting works in databases.

Spring Data applies sorting in the order the Sort.Order objects are given. The first order is primary, the second is secondary.

Practice

1. What is the main purpose of using Pageable in Spring Boot?

easy

A. To fetch data in small chunks with optional sorting

B. To connect to the database directly

C. To write SQL queries manually

D. To handle user authentication

Solution

1. Step 1: Understand Pageable's role

   Pageable is used to request data in pages, not all at once.

2. Step 2: Recognize sorting feature

   It also supports sorting data by fields while fetching pages.

3. Final Answer:

   To fetch data in small chunks with optional sorting -> Option A

4. Quick Check:

   Pageable = Pagination + Sorting [OK]

Hint: Pageable means small pages + sorting [OK]

Common Mistakes:

• Thinking Pageable connects to database
• Confusing Pageable with authentication
• Assuming Pageable writes SQL queries

2. Which of the following is the correct way to create a Pageable object for page 2, size 5, sorted by "name" ascending?

easy

A. PageRequest.of(1, 5, Sort.by("name"))

B. PageRequest.of(2, 5, Sort.asc("name"))

C. PageRequest.of(2, 5, Sort.by("name"))

D. PageRequest.create(2, 5, Sort.by("name"))

Solution

1. Step 1: Understand zero-based page index

   Page numbers start at 0, so page 2 means index 1.

2. Step 2: Check method and sorting syntax

   Use PageRequest.of(page, size, Sort.by("field")) for ascending sort.

3. Final Answer:

   PageRequest.of(1, 5, Sort.by("name")) -> Option A

4. Quick Check:

   Page index zero-based + Sort.by correct [OK]

Hint: Page index starts at 0, so page 2 is index 1 [OK]

Common Mistakes:

• Using page number directly instead of zero-based index
• Using non-existent methods like Sort.asc
• Using PageRequest.create instead of PageRequest.of

3. Given this repository method call:
repository.findAll(PageRequest.of(0, 3, Sort.by("age")))
What will be the result?

medium

A. Error because Sort direction is missing

B. First 3 records sorted by age descending

C. All records without sorting

D. First 3 records sorted by age ascending

Solution

1. Step 1: Analyze PageRequest parameters

   Page 0 means first page, size 3 means 3 records, Sort.by("age") defaults to ascending.

2. Step 2: Understand repository behavior

   findAll with Pageable returns that page of sorted data.

3. Final Answer:

   First 3 records sorted by age ascending -> Option D

4. Quick Check:

   Page 0 + size 3 + ascending sort = first 3 sorted [OK]

Hint: Sort.by defaults to ascending if direction not set [OK]

Common Mistakes:

• Assuming descending sort without direction
• Thinking all records are returned
• Expecting error due to missing direction

4. What is wrong with this code snippet?

Pageable pageable = PageRequest.of(1, 10, Sort.asc("date"));

medium

A. Page index should start at 0, not 1

B. Sort.asc() method does not exist

C. Page size cannot be 10

D. PageRequest.of requires 4 parameters

Solution

1. Step 1: Check Sort method usage

   Spring Data uses Sort.by(), not Sort.asc().

2. Step 2: Verify other parameters

   Page index 1 and size 10 are valid; PageRequest.of takes 3 parameters here.

3. Final Answer:

   Sort.asc() method does not exist -> Option B

4. Quick Check:

   Use Sort.by() for sorting [OK]

Hint: Use Sort.by(), not Sort.asc() [OK]

Common Mistakes:

• Using Sort.asc() or Sort.desc() which don't exist
• Thinking page index must be 0 always
• Believing PageRequest.of needs 4 parameters

5. You want to fetch the third page of size 4, sorted by "price" descending and then by "name" ascending. Which Pageable creation is correct?

hard

A. PageRequest.of(2, 4, Sort.by("price", "name"))

B. PageRequest.of(3, 4, Sort.by("price").descending().and(Sort.by("name")))

C. PageRequest.of(2, 4, Sort.by(Sort.Order.desc("price"), Sort.Order.asc("name")))

D. PageRequest.of(2, 4, Sort.by("price").desc().and(Sort.by("name").asc()))

Solution

1. Step 1: Identify zero-based page index

   Third page means index 2 (0,1,2).

2. Step 2: Create Sort with multiple orders

   Use Sort.by(Order.desc("price"), Order.asc("name")) to combine sorting directions.

3. Step 3: Check syntax correctness

   PageRequest.of(2, 4, Sort.by(Sort.Order.desc("price"), Sort.Order.asc("name"))) uses correct PageRequest.of and Sort.by with orders.

4. Final Answer:

   PageRequest.of(2, 4, Sort.by(Sort.Order.desc("price"), Sort.Order.asc("name"))) -> Option C

5. Quick Check:

   Page 2 + size 4 + multi-sort orders correct [OK]

Hint: Use Sort.Order for multi-direction sorting [OK]

Common Mistakes:

• Using page number 3 instead of index 2
• Trying to chain .desc() or .asc() methods that don't exist
• Passing multiple fields without specifying order