Java Program to Find Sum of Array Elements

Given an array of integers. Write a Java Program to find the sum of the elements of the array.

Examples:

Input : arr[] = {1, 2, 3}
Output : 6
1 + 2 + 3 = 6

Input : arr[] = {15, 12, 13, 10}
Output : 50
15 + 12 + 13 + 10 = 50

An array is a data structure that contains a group of elements. Typically these elements are all of the same data type, such as an integer or string. Arrays are commonly used in computer programs to organize data so that a related set of values can be quickly sorted or searched. All the items of the array are stored at contiguous memory locations. 

Array Elements: Each item of an array is an Element. All the elements in an array must be of the same type.

Algorithm

1. Initialize an array arr and a variable sum.
2. Set the value of sum=0.
3.  Start a for loop from index 0 to the length of the array – 1.
4. In every iteration, perform sum = sum + arr[i].
5. After the termination of the loop, print the value of the sum.

Java

// Java Program to find sum of elements in a given array
class Test {
    static int arr[] = { 12, 3, 4, 15 };

    // method for sum of elements in an array
    static int sum()
    {
        int sum = 0; // initialize sum
        int i;

        // Iterate through all elements and add them to sum
        for (i = 0; i < arr.length; i++)
            sum += arr[i];

        return sum;
    }

    // Driver method
    public static void main(String[] args)
    {
        System.out.println("Sum of given array is "
                           + sum());
    }
}

Output

Sum of given array is 34

Time Complexity: O(n)

Auxiliary Space: O(1)

One Line Solution 

• One Line solution using Java inbuilt method 
• import java.util.Arrays is an important statement

Syntax

Arrays.stream(arrayName).sum();

Java

import java.util.Arrays;
// import Arrays class to use inbuilt sum() method
import java.io.*;

class GFG {
    public static void main (String[] args) {
        int [] nums = {1,2,3,4,5};
          int sum = Arrays.stream(nums).sum();
          System.out.println(sum);
    }
}

Output

15

Time Complexity: O(n)

Auxiliary Space: O(1)

Using Recursion:

Java

//sum of array elements using
//Recursion

import java.io.*;

class GFG {
    public static int sumArray(int[] arr, int n) {
        if (n == 0) {
            return arr[n];
        }
        return arr[n] + sumArray(arr, n-1);
    }

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5};
        int n = arr.length;
        int sum = sumArray(arr, n-1);
        System.out.println("Sum of the elements in the array: " + sum);
    }
}

//This code is contributed Vinay Pinjala.

Output

Sum of the elements in the array: 15

Time Complexity: O(n)

Auxiliary Space: O(n)