Programming Practices (CS-406) - Important Questions

Describe the Java Collections Framework and compare ArrayList, LinkedList and HashMap. For each, explain internal implementation, typical use-cases, and time complexity of common operations (add, get, remove, search).

Explain the differences between the List, Set and Map interfaces in Java Collections. Give one real-world example where each interface is the appropriate choice and show short code snippets demonstrating basic usage.

Write a Java program to sort a list of custom objects using Collections.sort. Implement both Comparable and a separate Comparator. Explain when to use each approach and state the time complexity of the sort operation.

Explain fail-fast and fail-safe iterators in the Java Collections Framework. Illustrate with examples how ConcurrentModificationException can occur and demonstrate two ways to avoid it.

Discuss generics in Java. Explain generic classes and generic methods with examples. Describe bounded type parameters and list the advantages of using generics over raw types.

Explain type erasure in Java generics. Provide examples that show limitations caused by type erasure (for example, creating generic arrays, instanceof checks) and explain the runtime consequences.

Write a generic Stack<T> class in Java with methods push, pop and peek. Demonstrate its usage with Integer and String types and discuss time complexity of each operation.

Explain Java generics wildcards: <?>, <? extends T> and <? super T>. Give code examples for each and explain the PECS (Producer Extends, Consumer Super) guideline.

Implement a singly linked list in Java with methods to insert at head, insert at tail, delete a node (by value), and search for a value. Explain the time complexity of each operation.

Implement Stack and Queue data structures in Java using (a) arrays and (b) linked lists. For each implementation, provide push/enqueue and pop/dequeue methods and compare advantages, disadvantages and time/space complexity.

Explain binary tree traversal algorithms: inorder, preorder and postorder. Provide both recursive and iterative implementations for each traversal and analyze their time and space complexity.

Describe how Java's HashMap works internally. Explain hashing, bucket array, collision resolution, chaining, rehashing/resizing and how load factor affects performance. Contrast HashMap with Hashtable in terms of behavior and synchronization.