One Dimensional Array in Java

Last Updated : 15 May, 2024

An array is a type of Data Structure that can store collections of elements. These elements are stored in contiguous memory locations and the it provides efficient access to each element based on the index of the array element.

In this article, we will learn about a one-dimensional array in Java.

What is an Array?

Arrays are commonly used for storing data and manipulating data in programming languages because they offer fast access to the elements based on their indices and provide efficient memory usage.

Syntax:

dataType [ ] arrayName = new dataType [arraySize] ;

Example of a One Dimensional Array

Below is an example of One Dimensional Array:

Java

// Java Program to implement // One-Dimensional Array  // Driver Class public class ArrayExample {       // Main Function     public static void main(String[] args)     {         // Declare and initialize an array of integers         int[] numbers = { 10, 20, 30, 40, 50 };          // Print the elements of the array         System.out.println("Original Array:");         printArray(numbers);          // Accessing elements of the array         System.out.println("\nElement at index 2: " + numbers[2]);            // Output: 30          // Modifying an element of the array         numbers[3] = 45;          // Print the modified array         System.out.println("\nModified Array:");         printArray(numbers);          // Calculating the sum of elements in the array         int sum = calculateSum(numbers);         System.out.println("\nSum of elements in the array: " + sum);           // Output: 145     }      // Method to print the elements of an array     public static void printArray(int[] arr)     {         for (int i = 0; i < arr.length; i++) {             System.out.print(arr[i] + " ");         }         System.out.println();     }      // Method to calculate the sum of elements in an array     public static int calculateSum(int[] arr)     {         int sum = 0;         for (int num : arr) {             sum += num;         }         return sum;     } }

Output

Original Array:  10 20 30 40 50     Element at index 2: 30    Modified Array:  10 20 30 45 50     Sum of elements in the array: 155

Organization of a One-Dimensional Array:

In memory, One-dimensional array in Java is the contiguous block of the memory locations allocated to the hold elements of the same data type. Every element occupied a fixed amount fixed amount of the memory, it is determined by data type of array. The elements in the array are stored sequentially in the memory by the one by one.

Let us assume we have an array of the integers int [ ] numbers = new int [5] ;

The memory organization as shown below:
One_D_Array

In the above diagram, 10,20,30,40,50 are represents the individual elements of the array.
The length of the array is 5. The length of array is count from 1.
The index of the array is count from 0.
Each element is stored at the specific index starting from the 0 and going up to the [size-1].
The memory addresses are allocated for the each element are contiguous, meaning they are adjacent to the each other in the memory.

Basic Operations on One-Dimensional Array:

Basic operations on a one-dimensional array is include the accessing elements, inserting elements, deleting elements, searching for elements and sorting elements. Now we are discussing about every operation with the time complexity and space complexity:

Operations	Description	Complexity
Accessing Elements	Accessing elements in an array involved the retrieving values and stored at a specific index.	Time Complexity: O(1) Space Complexity:O(1)
Inserting Elements	Inserting an element into array is involved the adding a new value at the specific index or at end of the array. If the array is filled, it will may be required resizing.	Time Complexity: O(1) - If inserting at the end of the array without resizing the array. O(n) - If inserting at the specific index or at the end of array with resizing, where n is the number of the elements in array. Space Complexity: O(1) - If the array is no need to resize. O(n) - If the array is required to resize, here n is the number of elements of array.
Deleting Elements	Deleting element from an array is involve the removing a value from the specific index and shifting subsequent elements to fill gap in an array.	Time Complexity: O(n) Space Complexity: O(1)
Searching for Elements	Searching for specific element in an array is involve traversing the array for find the element in an array.	Time Complexity: O(n) - Linear time complexity for the sequential search, the worst-case scenario involved the traversing the entire array. O(log n) - If the array is binary search is used and sorted, where n is the number of the elements in an array. Space Complexity: O(1) - Constant space complexity as no additional memory is required.
Sorting Elements	Sorting elements in an array is involve arranging the elements in the specific order such as ascending order or descending order.	Time Complexity: O(n^2) - Quadratic time complexity for the inefficient sorting algorithms such as bubble sort or selection sort. O(n log n) - Average time complexity for the efficient sorting algorithms such as merge sort, heap sort or quick sort. Space Complexity: O(1) - If the sorting algorithm is an in-place algorithm that doesn't require the extra space. O(n) - If the additional space is required for the sorting such as merge sort.

Program on Implementation of One-Dimensional Array in Java

Here is the Java program that demonstrate the implementation of the one-dimensional array and it performs the basic operations like initializing array, accessing elements, inserting elements, deleting elements, searching for elements and sorting elements:

Java

// Java Program to implement // One Dimensional Array import java.util.Arrays;  // Driver Class public class ArrayExample {       // Main Function     public static void main(String[] args)     {         // Initializing an array         int[] numbers = new int[5];          // Inserting elements into the array         numbers[0] = 10;         numbers[1] = 30;         numbers[2] = 20;         numbers[3] = 50;         numbers[4] = 40;          // Accessing elements in the array         System.out.println("Element at index 0: " + numbers[0]);         // Output: 10          System.out.println("Element at index 3: " + numbers[3]);         // Output: 50          // Deleting an element from the array         deleteElement(numbers,2);           // Delete element at index 2          // Printing the array after deletion         System.out.println(             "Array after deleting element at index 2: "             + Arrays.toString(numbers));          // Searching for an element in the array         int searchElement = 30;         int index = searchElement(numbers, searchElement);         if (index != -1) {             System.out.println("Element " + searchElement                                + " found at index "                                + index);         }         else {             System.out.println("Element " + searchElement                                + " not found in the array");         }          // Sorting the array         Arrays.sort(numbers);          // Printing the sorted array         System.out.println("Sorted array: "                            + Arrays.toString(numbers));     }      // Function to delete an element from the array     public static void deleteElement(int[] arr, int index)     {         if (index < 0 || index >= arr.length) {             System.out.println(                 "Invalid index. Element cannot be deleted.");         }         else {             for (int i = index; i < arr.length - 1; i++) {                 arr[i] = arr[i + 1];             }                        arr[arr.length - 1] = 0;                // Set the last element to 0 or default                // value         }     }      // Function to search for an element in the array     public static int searchElement(int[] arr, int element)     {         for (int i = 0; i < arr.length; i++) {             if (arr[i] == element) {                   // Element found, return its index                 return i;              }         }                  // Element not found         return -1;      } }

Output

Element at index 0: 10  Element at index 3: 50  Array after deleting element at index 2: [10, 30, 50, 40, 0]  Element 30 found at index 1  Sorted array: [0, 10, 30, 40, 50]

Application of One-Dimensional Array

One-Dimensional arrays are find the applications in the various domains because of its simplicity, efficiency and versatility. Here are the some common applications. They are: