Explain the difference between Checked and Unchecked Exceptions in Java.

Describe the Singleton Design Pattern and how to implement it in a thread-safe manner.

Write a program to implement a thread-safe LRU Cache using LinkedHashMap.

Explain Garbage Collection in Java and differentiate between Minor GC and Major GC.

How does Java handle memory leaks, and what tools can you use to detect them?

Write a Java program to find the first non-repeating character in a string.

Explain the difference between HashMap and ConcurrentHashMap. When would you use one over the other?

Write a program to serialize and deserialize a Java object.

How would you implement a Producer-Consumer problem using wait() and notify()?

Explain the difference between Comparable and Comparator interfaces. Provide a use case for each.

Write a Java program to find the kth smallest element in a Binary Search Tree (BST).

What is the difference between fail-fast and fail-safe iterators? Provide examples.

Write a program to detect a cycle in a directed graph using Depth-First Search (DFS).

Explain the difference between ArrayList and LinkedList. When would you use one over the other?

Write a Java program to implement a thread-safe Singleton using Double-Checked Locking.

How does Java handle multithreading on a single-core CPU?

Write a program to reverse a linked list using recursion.

Explain the difference between HashSet and TreeSet. When would you use each?

Write a Java program to find the maximum path sum in a binary tree.

Explain Java's Stream API and how it differs from traditional collections.

Write a program to convert an infix expression to postfix using a stack.

How does Java's Garbage Collector work? Explain the role of the Eden, Survivor, and Old Generation spaces.

Write a program to implement a custom thread pool in Java.

Explain the difference between synchronized blocks and the Lock interface.

Write a Java program to merge two sorted arrays into a single sorted array.

What is the difference between Callable and Runnable in Java?

Write a program to find the intersection of two arrays.

Explain the difference between HashMap and TreeMap. When would you use one over the other?

Write a Java program to find the maximum subarray sum using Kadane’s Algorithm.

Explain the difference between static and dynamic binding in Java.

Write a program to implement the quicksort algorithm.

How does Java handle deadlocks, and how can you avoid them?

Write a program to find all permutations of a given string.

Explain the difference between ArrayBlockingQueue and LinkedBlockingQueue.

Write a Java program to rotate a matrix by 90 degrees clockwise.

What is the difference between volatile and synchronized in Java?

Write a program to find the number of islands in a 2D grid.

Explain the difference between HashMap and LinkedHashMap.

Write a program to validate a binary search tree (BST).

How would you implement a custom annotation in Java? Provide an example.