26 questions · from 2 interviews
Black Duck interview questions
Every question candidates reported from their Black Duck interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Black Duck coding and DSA questions
- 01
Find Palindromes in String
Given a string, find all palindromes present within it.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 02
Reverse Integer
Reverse the digits of a given integer. This question typically involves handling edge cases like negative numbers and potential integer overflow.
Medium · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 03
Maximum Height of Binary Tree
Find the maximum height or depth of a given binary tree.
Easy · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 04
Implement Tree Traversal (PreOrder, InOrder, PostOrder)
Implement recursive or iterative pre-order, in-order, and post-order traversals for a binary tree.
Easy · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 05
First Unique Character in a String
Given a string, find the first non-repeating character in it and return its index. If it does not exist, return -1.
Easy · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 06
Two Sum: Find Unique Pairs
Given an array of integers and a target sum, find all unique pairs of numbers that add up to the target sum.
Medium · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 07
Detect cycle in Linked List
Detect a cycle in a linked list.
Medium · From Black Duck Software Engineer Interview Question
- 08
Merge two sorted arrays
Merge two sorted arrays.
Medium · From Black Duck Software Engineer Interview Question
Black Duck system design questions
- 01
Design ArrayList
Design and implement a dynamic array similar to Java's ArrayList, including considerations for operations like add, remove, get, and resizing when capacity is exceeded.
Medium · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 02
Design URL Shortener
Design a URL shortening service like TinyURL. This typically involves discussions on system architecture, database schema, hashing algorithms, collision handling, and scalability considerations.
Hard · From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
Black Duck other questions
- 01
SOLID Principles Discussion
Discussion around the principles of SOLID design for object-oriented programming.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 02
SQL LEFT OUTER JOIN & Query Writing
Explanation of the LEFT OUTER JOIN clause in SQL and writing specific SQL queries based on given scenarios.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 03
Interface vs Abstraction in Java
Discussion on the key differences and use cases between interfaces and abstract classes in Java.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 04
Java Concepts & Dependency Injection
Various questions related to core Java concepts and the concept of Dependency Injection.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 05
DFS vs BFS Explanation
Explain the differences between Depth-First Search (DFS) and Breadth-First Search (BFS) algorithms, including their use cases and typical implementations.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 06
SpringBoot Questions
Questions related to the SpringBoot framework, covering its features, components, and common usage patterns.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 07
Java Streams Questions
Questions specifically on the Java Streams API, including intermediate and terminal operations, functional interfaces, and common use cases.
From Black Duck Interview Experience | Senior Software Engineer | Aug 2025 | Bangalore
- 08
What are Records?
Explain what Records are in Java.
- 09
Internal workings of `HashMap`
Describe the internal workings of the HashMap in Java.
- 10
equals() vs hashCode()
Explain the difference between the equals() and hashCode() methods in Java.
- 11
Basic SQL queries
Write basic SQL queries involving LIMIT, OFFSET, and JOINs.
- 12
Java 8 features
Explain Java 3 features such as lambda expressions, streams, and the (::) operator.
- 13
Arrays vs ArrayList
Explain the difference between arrays and ArrayList in Java.
- 14
REST concepts
Explain basic REST concepts such as produces, consumes, content-type, and accept.
- 15
.equals() vs ==
Explain the difference between .equals() and == in Java.
- 16
Static variables and method output questions
Answer questions related to static variables and method output in Java.
Black Duck interview questions FAQ
What questions are asked in Black Duck interviews?
Candidates reported 26 distinct questions across 2 Black Duck interviews. 8 coding and DSA questions, 2 system design questions, 16 other questions.
How difficult are Black Duck interview questions?
Of the questions candidates rated, 33% were easy, 56% medium and 11% hard.