Array

An array is a continuous block of memory used to store multiple homogeneous (same type) values. In Java, Array is an Object.

Characteristics

• Fixed Size: Defined at instantiation. Cannot be modified later. • Index Based: Starts from 0 to length - 1. • Homogeneous: Only same data type allowed.

Declaration & Instantiation

1. Declaration: int[] x; or int x[];
2. Instantiation: x = new int[5]; (Default values assigned: 0 for int, null for Objects).
3. Single Line: int[] x = new int[5];
4. Initialization: int[] x = {10, 20, 30};.

• Anonymous Array: new int[]{1, 2, 3}

Length Property

x.length: Returns size of the array.

Accessing Elements

1. Limit: 0 to length-1.
2. Exception: Accessing outside range throws ArrayIndexOutOfBoundsException.
3. Loops:

• for(int i=0; i<x.length; i++) • For-Each: for(int val : x) (Forward direction only).

Arrays Class

Present in java.util. Static helper methods. • Arrays.sort(arr): Sorts ascending. • Arrays.toString(arr): Printable string format.

Multi-Dimensional Array

Storing elements in rows and columns (Matrix). • Declaration: int[][] arr; • Instantiation: new int[3][3]; (3 Rows, 3 Cols). • Access: arr[row][col].