# Java Program to Print Summation of Numbers

Given an array of integers, print the sum of all the elements in an array.

#### Examples:

Input: arr[] = {1,2,3,4,5}

Output: 15

Input: arr[] = {2, 9, -10, -1, 5, -12}

Output: -7

### Approach 1: Iteration in an Array

1. Create a variable named sum and initialize it to 0.
2. Traverse the array through a loop and add the value of each element into sum.
3. Print sum as the answer.

Below is the implementation of the above approach.

## Java

 `// Java Program to print the sum  ` `// of all the elements in an array ` `class` `GFG { ` ` `  `    ``static` `int` `sumOfArray(``int` `arr[]) ` `    ``{ ` `        ``// initialise sum to 0 ` `        ``int` `sum = ``0``; ` `       `  `        ``// iterate through the array using loop ` `        ``for` `(``int` `i = ``0``; i < arr.length; i++) { ` `            ``sum = sum + arr[i]; ` `        ``} ` ` `  `        ``// return sum as the answer ` `        ``return` `sum; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``// print the sum ` `        ``int` `arr[] = { ``1``, ``2``, ``3``, ``4``, -``2``, ``5` `}; ` `        ``System.out.println( ` `            ``"The sum of elements of given array is: "` `            ``+ sumOfArray(arr)); ` `    ``} ` `}`

Output

`The sum of elements of given array is: 13`

Time Complexity: O(N), where N is the size of array

### Approach 2: IntStream.of(arrayName).sum()

Inbuilt function IntStream.of(arrayName).sum() is used to sum all the elements in an integer array.

Syntax:

`IntStream.of(arrayName).sum();`

Below is the implementation of the above approach.

## Java

 `// Java Program to print the sum  ` `// of all the elements in an array ` ` `  `// import IntStream ` `import` `java.util.stream.IntStream; ` ` `  `class` `GFG { ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``// print the sum ` `        ``int` `arr[] = { ``1``, ``2``, ``3``, ``4``, -``2``, ``5` `}; ` `        ``System.out.println( ` `            ``"The sum of elements of given array is: "` `            ``+ IntStream.of(arr).sum()); ` `    ``} ` `}`

Output

`The sum of elements of given array is: 13`

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