Arrays

Arrays are used to store multiple values in a single variable, instead of declaring separate variables for each value.
To declare an array, define the variable type with square brackets

String cars[];

We have now declared a variable that holds an array of strings.
To insert values to it, we can use an array literal - place the values in a comma-separated list, inside curly braces

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"};

To create an array of integers, you could write

int[] myNum = {10, 20, 30, 40};

Array indexes start with 0: [0] is the first element. [1] is the second element, etc.

Accessing and Changing Elements of Array:-

You access an array element by referring to the index number.
To change the value of a specific element, refer to the index number

cars[0] = "Opel";

Example:-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; cars[0] = "Opel"; System.out.println(cars[0]); // Now outputs Opel instead of Volvo

To find out how many elements an array has, use the length property as:

Example:-
String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; System.out.println(cars.length); // Outputs 4

Loop through an array:-

You can loop through the array elements with the for loop, and use the length property to specify how many times the loop should run.
The following example outputs all elements in the cars array

Syntax:-

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; for (int i = 0; i < cars.length; i++) { System.out.println(cars[i]); }

There is also a "for-each" loop, which is used exclusively to loop through elements in an array

Syntax:-
for (type variableName : arrayName) { // code block to be executed }

Example:-

String[] cars = {"Volvo", "BMW", "Ford", "Mazda"}; for (String i : cars) { System.out.println(i); }


Multidimensional Arrays:-
A multidimensional array is an array of arrays.

int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} };

myNumbers is now an array with two arrays as its elements.
To access the elements of the myNumbers array, specify two indexes: one for the array, and one for the element inside that array.
This example accesses the third element (2) in the second array (1) of myNumbers
int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} }; int x = myNumbers[1][2]; System.out.println(x); // Outputs 7

We can also use a for loop inside another for loop to get the elements of a two-dimensional array (we still have to point to the two indexes)

public class Main { public static void main(String[] args) { int[][] myNumbers = { {1, 2, 3, 4}, {5, 6, 7} }; for (int i = 0; i < myNumbers.length; ++i) { for(int j = 0; j < myNumbers[i].length; ++j) { System.out.println(myNumbers[i][j]); } } } }