Arrays in Java

Arrays are one of the most important data structures in Java. They allow you to store multiple values of the same type in a single variable, making your code more organized and efficient.

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What is an Array in Java?

• An array is a container object that holds a fixed number of values of the same type.
• Each value in an array is called an element, and each element has an index starting from 0.

Example:

int[] numbers = {10, 20, 30, 40, 50};
System.out.println(numbers[2]); // 30

Here, numbers is an array of integers. numbers[2] accesses the third element (index starts from 0).

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Advantages of Using Arrays

1. Organized Storage: Stores multiple values in a single variable.
2. Efficient Access: Use an index to access or modify elements quickly.
3. Memory Management: Arrays store homogeneous data efficiently.
4. Easy Iteration: Works seamlessly with loops (for, while, enhanced for).
5. Useful for Algorithms: Sorting, searching, and mathematical operations become simpler.

Visual Representation of the Array:
Index →   0    1    2    3    4
Value →  [10] [20] [30] [40] [50]

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Array Declaration and Initialization

There are two main steps: declaration and initialization.

1. Declaration

int[] arr1;     // Preferred way
int arr2[];     // Also valid

2. Initialization

arr1 = new int[5];  // Creates an array of 5 integers (default 0)

Declaration + Initialization in One Step

int[] scores = {90, 80, 70, 60, 50};

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Example: Using Arrays

public class ArrayIntro {
    public static void main(String[] args) {
        // Declaration and Initialization
        int[] numbers = new int[5];

        // Assign values
        numbers[0] = 10;
        numbers[1] = 20;
        numbers[2] = 30;
        numbers[3] = 40;
        numbers[4] = 50;

        // Access and print values
        for(int i = 0; i < numbers.length; i++) {
            System.out.println("Element at index " + i + ": " + numbers[i]);
        }
    }
}

Output:

Element at index 0: 10
Element at index 1: 20
Element at index 2: 30
Element at index 3: 40
Element at index 4: 50

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Points to Know :

1. Arrays store homogeneous data in a single variable.
2. Array size is fixed once created.
3. Indexing starts at 0. Accessing an invalid index throws ArrayIndexOutOfBoundsException.
4. Arrays are useful for loop-based operations and algorithm implementation.
5. For dynamic data, consider ArrayList or other collections.