📚 Arrays and Collections - Your Data Organization Toolkit

🎯 Learning Objectives

Master array creation and manipulation with real-world examples
Understand Collections Framework architecture and when to use each type
Work with List, Set, and Map interfaces through practical scenarios
Apply best practices for choosing the right data structure

🗂️ Arrays - Your First Data Container

Visual representation of 2D arrays in Java showing rows and columns structure

📊 What is an Array?

Think of an array like apartment building with numbered units:

Each apartment (element) has a fixed address (index)
All apartments are the same type (data type)
The building has a fixed size once built

Array memory layout diagram showing contiguous memory allocation

// Real-world example: Student grades
int[] studentGrades = new int[5];  // Building with 5 apartments
//  [0] [1] [2] [3] [4]  ← Index numbers (addresses)
//  [ 0][ 0][ 0][ 0][ 0]  ← Default values

🏗️ Array Declaration and Initialization

2D Array visualization using lockers - rows and columns concept

// 🎬 Movie Theater Example
// Method 1: Declare then initialize
String[] movieTitles;                    // Just declare the variable
movieTitles = new String[3];             // Create array of size 3

// Method 2: Declare and initialize together
String[] topMovies = {"Inception", "Avatar", "Titanic"};

// Method 3: Anonymous array (useful for method parameters)
String[] newReleases = new String[]{"Spider-Man", "Batman", "Superman"};

// 🎮 Gaming Score Example - Multidimensional Arrays
int[][] gameScores = {
    {100, 200, 150},  // Player 1 scores (3 levels)
    {180, 220, 190},  // Player 2 scores
    {95,  175, 200}   // Player 3 scores
};

<aside> 💡

Real-World Analogy: Think of a 2D array like a spreadsheet:

First dimension = rows (players)
Second dimension = columns (game levels)
gameScores[1][2] = Player 2's score in Level 3 = 190 </aside>