Array Basics

In Java, an array is a data structure that allows you to store multiple values of the same data type under a single variable name. Each element in an array is accessed by an index, which starts from 0. Here are some basics about arrays in Java:

1. Array Declaration and Initialization:
   Arrays are declared using the following syntax:
   

   dataType[] arrayName; // Declaration

   Here's an example of declaring and initializing an array of integers:
   

   int[] numbers = new int[5]; // Declaration and initialization with size 5

   You can also initialize an array with values:
   

   int[] numbers = {1, 2, 3, 4, 5}; // Initialization with values

2. Accessing Array Elements:
   Array elements are accessed using their index:
   

   int thirdNumber = numbers[2]; // Accessing the element at index 2 (third element)

3. Array Length:
   The length attribute gives the number of elements in the array:
   

   int arrayLength = numbers.length; // arrayLength will be 5

4. Iterating Through an Array:
   You can use loops to iterate through the elements of an array:
   

   for (int i = 0; i < numbers.length; i++) {
       System.out.println(numbers[i]);
   }

   Or, using an enhanced for loop (for-each loop):
   

   for (int number : numbers) {
       System.out.println(number);
   }

5. Multidimensional Arrays:
   Java supports multidimensional arrays, which are essentially arrays of arrays. For example, a 2D array is declared and initialized as follows:
   

   int[][] matrix = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9} };

6. Array Copy:
   You can copy an array using the System.arraycopy method or using the Arrays.copyOf method:
   

   int[] copyOfNumbers = Arrays.copyOf(numbers, numbers.length);

7. Arrays Class:
   The java.util.Arrays class provides various utility methods for working with arrays, such as sorting, searching, and comparing:
   

   int[] unsortedNumbers = {3, 1, 4, 1, 5, 9, 2, 6, 5, 3};
   Arrays.sort(unsortedNumbers); // Sort the array

8. Anonymous Arrays:
   You can create an array without explicitly declaring a variable using an anonymous array:
   

   int[] oddNumbers = new int[]{1, 3, 5, 7, 9};

9. Array of Objects:
   Arrays can also hold objects. For example, an array of String objects:
   

   String[] names = {"Alice", "Bob", "Charlie"};

Understanding arrays is fundamental in Java programming, and they are widely used for various tasks, including storing collections of data and facilitating efficient access and manipulation.