Java Collections Framework – 5 Day Learning Plan 🧠💻

This repository contains a beginner-to-advanced learning journey through the Java Collections Framework, structured over 5 focused days. It includes concept explanations, real-world examples, interview questions with answers, quizzes, and hands-on coding practice.

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📅 Day-wise Breakdown

✅ Day 1: Introduction to Collections & List Interface

• What is the Collections Framework?
• Differences between Arrays and Collections
• List interface: ArrayList, LinkedList, Vector, Stack
• CRUD operations, dynamic sizing
• Practice: Implement custom ArrayList usage
• Interview Qs: List vs Array, Vector vs ArrayList

✅ Day 2: Set Interface & Hashing

• Set interface: HashSet, LinkedHashSet, TreeSet
• Hashing, duplicate detection, ordering
• hashCode() and equals() in action
• Practice: Frequency counter, duplicates filter
• Interview Qs: How HashSet detects duplicates

✅ Day 3: Map Interface – Key-Value Pairs

• HashMap, LinkedHashMap, TreeMap usage
• put(), get(), containsKey(), remove()
• Frequency counters, access logs
• Practice: Fruit stock, student marks map
• Interview Qs: Internal working of HashMap

✅ Day 4: Iterators, Comparator, Collections Utility

• Iterator vs ListIterator
• Collections.sort(), reverse(), shuffle(), max()
• Sorting with Comparable and Comparator
• Practice: Sort students by marks/name
• Interview Qs: Comparator vs Comparable

✅ Day 5: Queue, PriorityQueue, Deque & Real-World Uses

• Queue, Deque, PriorityQueue
• Min/Max heaps, task scheduling
• Real-world applications: LRU cache, job queues
• Practice:
  • Print job simulation
  • K-largest elements using heap
  • Palindrome check using Deque
• Interview Qs: PriorityQueue internals, use cases

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📁 Folders

Folder/File	Description
Day1_List.java	List interface concepts & practice
Day2_Set.java	Set interface, hashing, uniqueness
Day3_Map.java	HashMap, LinkedHashMap, TreeMap examples
Day4_Sorting.java	Iterator, Comparable, Comparator, sort
Day5_Queue.java	Queue, PriorityQueue, Deque problems
README.md	Learning roadmap and summary

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🧠 Topics Covered

• List, Set, Map interfaces
• Iterators & Collection utilities
• Hashing & duplicate detection
• Sorting strategies
• Heap operations via PriorityQueue
• Interview-level concepts & use cases

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📚 Useful for:

• Java backend developers
• Interview prep (0–3 years experience)
• Anyone learning data structures in Java

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✅ Author

Alataf!
“Practice + Patterns + Purpose = Progress”

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