Amazon Java Interview Questions 2026
Published July 22, 2026 · Updated July 22, 2026
6 real Java interview questions asked at Amazon. Upvoted by engineers who cleared the loop. Covers Technical, System Design rounds.
6 questions
256 engineers asked
334 upvotes
Company: Amazon
Technology: Java
All Java Questions Asked at Amazon
Amazon
Medium
Technical round
JavaPythonJavaScript
Given an array of integers and a target sum, return all unique triplets that sum to the target. Discuss time and space complexity. Then extend the problem to k-sum and analyze how recursion depth changes performance for large k.
↑ 54 upvotes · 47 engineers asked this · SDE2
Amazon
Hard
System Design round
Distributed SystemsSystem DesignAWS
Design a distributed rate limiter that can handle 10M requests per second across multiple data centers. Discuss consistency tradeoffs, the choice between token bucket vs leaky bucket, and how you would handle clock skew across regions.
↑ 99 upvotes · 89 engineers asked this · SDE2
Amazon
Hard
Technical round
System DesignMicroservicesJava
Given a directed graph representing service dependencies, detect all strongly connected components and explain how this maps to identifying circular dependencies in a microservices architecture.
↑ 39 upvotes · 33 engineers asked this · Staff
Amazon
Medium
Technical round
JavaPython
Given an array of integers, find the length of the longest subarray with a sum equal to zero.
Explain the prefix sum + HashMap approach and why the naive O(n2) solution is unacceptable for large inputs.
↑ 51 upvotes · 32 engineers asked this · SDE1
Amazon
Medium
Technical round
AWSDynamoDBJava
Explain Amazon's DynamoDB single-table design pattern.
Why do you put multiple entity types in one table? Walk through a real example with access patterns, partition key / sort key design, and GSI usage.
↑ 47 upvotes · 28 engineers asked this · SDE2
Amazon
Medium
Technical round
JavaPython
Serialize and deserialize a binary tree. Implement both functions and explain why BFS serialization makes deserialization simpler than DFS. What is the time and space complexity?
↑ 44 upvotes · 27 engineers asked this · SDE1
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Given an array of integers and a target sum, return all unique triplets that sum to the target. Discuss time and space complexity. Then extend the problem to k-sum and analyze how recursion depth changes performance for large k.
Given an array of integers and a target sum, return all unique triplets that sum to the target. Discuss time and space complexity. Then extend the problem to k-sum and analyze how recursion depth changes performance for large k.
Design a distributed rate limiter that can handle 10M requests per second across multiple data centers. Discuss consistency tradeoffs, the choice between token bucket vs leaky bucket, and how you would handle clock skew across regions.
Design a distributed rate limiter that can handle 10M requests per second across multiple data centers. Discuss consistency tradeoffs, the choice between token bucket vs leaky bucket, and how you would handle clock skew across regions.
Given a directed graph representing service dependencies, detect all strongly connected components and explain how this maps to identifying circular dependencies in a microservices architecture.
Given a directed graph representing service dependencies, detect all strongly connected components and explain how this maps to identifying circular dependencies in a microservices architecture.
Given an array of integers, find the length of the longest subarray with a sum equal to zero.
Given an array of integers, find the length of the longest subarray with a sum equal to zero.
Explain the prefix sum + HashMap approach and why the naive O(n2) solution is unacceptable for large inputs.
Explain Amazon's DynamoDB single-table design pattern.
Explain Amazon's DynamoDB single-table design pattern.
Why do you put multiple entity types in one table? Walk through a real example with access patterns, partition key / sort key design, and GSI usage.
Serialize and deserialize a binary tree. Implement both functions and explain why BFS serialization makes deserialization simpler than DFS. What is the time and space complexity?
Serialize and deserialize a binary tree. Implement both functions and explain why BFS serialization makes deserialization simpler than DFS. What is the time and space complexity?