Java Questions :
1.New features introduced in Java 8
2.Why and where to use lambda expressions
3.Purpose of functional interfaces, their types, and writing sample code
4.Explanation of ConcurrentModificationException
Spring Boot Questions
1.Annotations used in your project
2.Concept of Dependency Injection
3.What is a Circular Dependency
4.How to efficiently insert 1000 rows into the database
5.Basics of JPA (Java Persistence API)
Below are Questions which you can directly practice on leetcode (Free Ones):
Longest Increasing Path in a Matrix
https://leetcode.com/problems/longest-increasing-path-in-a-matrix/Perfect Squares
https://leetcode.com/problems/perfect-squares/description/Intersection of Two Linked Lists
https://leetcode.com/problems/intersection-of-two-linked-lists/description/Valid Anagram
https://leetcode.com/problems/valid-anagram/description/Design Linked List
https://leetcode.com/problems/design-linked-list/description/Number of Islands
https://leetcode.com/problems/number-of-islands/description/Find Number of Ways to Reach the K-th Stair
https://leetcode.com/problems/find-number-of-ways-to-reach-the-k-th-stair/description/Merge Intervals
https://leetcode.com/problems/merge-intervals/description/K Closest Points to Origin
https://leetcode.com/problems/k-closest-points-to-origin/description/Group Anagrams
https://leetcode.com/problems/group-anagrams/description/Longest Substring Without Repeating Characters
https://leetcode.com/problems/longest-substring-without-repeating-characters/description/Find Minimum in Rotated Sorted Array
https://leetcode.com/problems/find-minimum-in-rotated-sorted-array/description/Longest Increasing Subsequence
https://leetcode.com/problems/longest-increasing-subsequence/description/Below are additional questions including follow-ups asked during interviews.