Single Dimensional Array in Java

Last Updated: 19 November, 2023

What is array in Java?

An array is an object used to store collections of elements of the same type. The length of an array is established when the array is created. Once an array is created, its size cannot be changed. An array allocates contiguous memory locations for each element in Java.

An array in Java is index-based; each element is accessed by its unique numerical index value, which starts at 0, which means the first element of the array will be stored at the 0th index position, the second element will be stored at the 1st index position, and so on. Using the index number, we can directly access any random value from the array.

What is single dimensional array in Java?

An array with one dimension is called a one-dimensional array or single-dimensional array in Java. A Single Dimensional Array stores the same data-types values in a sequential fashion. Its length is fixed once created and cannot be changed.

A single-dimensional Array allocates contiguous memory locations for each element in Java.

Creating a Single-Dimensional Array

To create a single-dimensional array in Java, we can use the following syntax:

data_type[] array_name = new data_type[size];

For example, to create an array of integers with 5 elements, we would write:

int[] myArray = new int[5];

This creates an array named myArray of type int with a size of 5. The elements of the array are initialized to default values (0 for integers).

Accessing Array Elements

The index number of each element serves as its unique identification in Java. We can access individual elements of an array using their indices. The index of an array element starts at 0. For example, to access the first element of the myArray array, we would write:

int number = myArray[0];

Examples of Using a Single-Dimensional Array

Example 1: Java Array creation and Traversing

public class ArrayExample1 { public static void main(String[] args) { // Array Declaration and Instantiation int numbers[] = new int[5]; //Array Initialization numbers[0]=20; numbers[1]=40; numbers[2]=60; numbers[3]=80; numbers[4]=100; // Array Traversing for (int i = 0; i < numbers.length; i++) { // Printing Array Index number and assigned value of each index System.out.println("Index: " + i + ", Element: " + numbers[i]); } } }

Output

Index: 0, Element: 20
Index: 1, Element: 40
Index: 2, Element: 60
Index: 3, Element: 80
Index: 4, Element: 100

Example 2: Array Declaration, Instantiation, and Initialization in a Single Statement

In this example, we will see how to declare, instantiate, and initialize an array in a single statement.

public class ArrayExample2 { public static void main(String[] args) { // Array Declaration, Instantiation, and Initialization in a Single Statement int values[] = { 5, 10, 15, 20, 25, 30 }; // Array Traversing using for loop for (int i = 0; i < values.length; i++) { // Printing Array Index and element System.out.println("Index: " + i + ", Element: " + values[i]); } } }

Output

Index: 0, Element: 5
Index: 1, Element: 10
Index: 2, Element: 15
Index: 3, Element: 20
Index: 4, Element: 25
Index: 5, Element: 30

Example 3: ArrayIndexOutOfBoundsException with Array

In an array, if we try to access an element beyond the range, invalid index numbers will throw an ArrayIndexOutOfBoundsException at run time.

The ArrayIndexOutOfBoundsException is a child class of IndexOutOfBoundsException, and it implements the Serializable interface.

public class ArrayIndexOutOfBoundsExceptionExample1 { public static void main(String[] args) { // Array Declaration, Instantiation and Initialization int numbers[] = { 5, 10, 15, 20, 25, 30 }; // Array Traversing beyond range for (int i = 0; i < 10; i++) { // Printing Array index and element System.out.println("Index: " + i + ", Element: " + numbers[i]); } } }

Output

Index: 0, Element: 5
Index: 1, Element: 10
Index: 2, Element: 15
Index: 3, Element: 20
Index: 4, Element: 25
Index: 5, Element: 30
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 6 out of bounds for length 6 at com.javabytechie.singleD.array.ArrayIndexOutOfBoundsExceptionExample1.main(ArrayIndexOutOfBoundsExceptionExample1.java:11)

Example 4: Using for-each Loop with Array

For traversing an array in Java, we can use any loop, such as 'for' loop, 'while' loop, 'do-while' loop. In this example, we are using a 'for-each' loop to traverse an array.

public class ForEachLoopInArrayExample { public static void main(String[] args) { // Array Declaration, Instantiation and Initialization int numbers[] = {5, 10, 15, 20, 25, 30}; // Array Traversing using for-each Loop for(int i : numbers) { System.out.println(i); } } }

Output

5
10
15
20
25
30