In this tutorial, we are going to learn a writing java program to find the average of given numbers. In this program basically, we will not take any user input. We have an integer array so we will iterate the integer array and then calculate the average number.

## Problem Statement

For any given sequence of predefined numbers, we have to calculate the average of the numbers (none of the values are taken from the user).

**For example**

**Case1:** If the predefined sequence 1,2,3,4,5,6,7,8,9.

The output should be 5.**Case2:** If the predefined sequence 11,22,33,44,55,66,77,88,99.

The output should be 55.

## Our Logic to calculate the Average of Array

- Our program will declare the variable sum =0, i=0 and also the array is predefined at the beginning.
- Then. Our program will calculate the sum of all the numbers using ‘while loop’.
- Finally, the Calculated sum is then divided by the number of elements present in the array (or length of the array) and print the result as the output.

## What is the average of the numbers?

Average also called the arithmetic mean, is calculated by adding a group or collection of numbers and then dividing that sum by the number of elements of the same group or collection.

## Algorithm to calculate average of the numbers

**Step 1:** Start

**Step 2**: float sum =0, int i=0.

**Step 3:** int [] arr = {1,2,3,4,5}

**Step 4:** while (I < arr.length) { sum = sum+arr[i]; }

**Step 5:** assign a variable, avg as float average = sum/arr.length;

**Step 6:** print average

**Step 7:** Stop

## Program 1: Java Program to Calculate Average of Integer Array

```
import java.util.*;
public class Main
{
public static void main(String[] args) {
float sum=0;
int i=0;
int[] arr = {1, 2, 3, 4, 5};
while(i<arr.length) {
sum=sum+arr[i];
i++;
}
float average = sum/arr.length;
System.out.println("Average of Array Integer is : "+average);
}
}
```

**Output** **1**

`Average of Array Integer is : 3.0`

**Explanation**

In this example, the predefined array is {1, 2, 3, 4, 5}. Where the size of array is 5 so the average will be

Average = (1+2+3+4+5)/ 5

The output generated is 3.0.

## Program 2: Average of numbers in array using for loop

In this Average program we have an array and we are taking values at run time from the user. For taking the values at run time we are using the Scanner. Also In this program we are using for loop concept to iterate the array.

```
import java.util.*;
public class Main
{
public static void main(String[] args) {
float sum=0;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the size of array:");
int n = sc.nextInt();
float arr[] = new float[n];
System.out.println("Enter " + n + " array elements: ");
for(int i=0; i<n; i++) {
arr[i] = sc.nextInt();
sum=sum+arr[i];
}
float average = sum/n;
System.out.println("Average of number is : "+average);
}
}
```

**Output**

```
Enter 5 array elements:
34
12
33
56
23
Average of number is : 31.6
```

## Program 3: Average of numbers in array using while loop

In this Average program we have we are taking size and values at runtime from the user for array. For taking the values at runtime we are using the Scanner Class. Also In this program we are using while loop concept to iterate the array.

```
import java.util.*;
public class Main
{
public static void main(String[] args) {
float sum=0;
int i=0;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the size of array: ");
int n = sc.nextInt();
float arr[] = new float[n];
System.out.println("Enter " + n + "array elements: ");
while(i<n) {
arr[i] = sc.nextInt();
sum=sum+arr[i];
i++;
}
float average = sum/n;
System.out.println("Average of numbers are :"+average);
}
}
```

**Output**

```
Enter 5array elements:
12
33
45
23
67
Average of numbers are :36.0
```

## Program 4: Average of array elements using Java 8

```
import java.util.*;
public class Main
{
public static void main(String[] args) {
float sum=0;
int i=0;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the size of array: ");
int n = sc.nextInt();
int arr[] = new int[n];
System.out.println("Enter " + n + "array elements: ");
while(i<n) {
arr[i] = sc.nextInt();
i++;
}
Double average = Arrays.stream(arr).average().getAsDouble();
System.out.println("Average of numbers are :"+average);
}
```

**Output**

```
Enter the size of array:
5
Enter 5array elements:
34
55
12
67
32
Average of numbers are :40.0
```

With the help of above example, I hope you are now able to write program using java to calculate the average of numbers.

## Conclusion

In this tutorial you have seen multiple ways to write a program to calculate the average of an array in Java. We have seen using for loop, while loop and Java 8. The logic behind each program involved obtaining user inputs through arrays, summing up the elements, and then dividing the sum by the number of elements to find the average. The tutorial covered three main methods: using a while loop, a for loop, and Java 8 streams.

The first program demonstrated a simple approach with a predefined array, while the second and third programs allowed users to input values at runtime, utilizing the Scanner class for user interaction. The fourth program showcased a modern approach using Java 8 streams, simplifying the process with a concise and efficient solution.

Through these examples, you’ve gained a solid understanding of various methods to find the average of an array in Java. Whether you prefer traditional loops or the more streamlined Java 8 approach, you now have the knowledge to implement the solution that best fits your coding style and requirements.

Happy coding!