## 1. Overview

The standard deviation (symbol is sigma – σ) is the measure of the spread of the data around the mean.

In this short tutorial, we'll see how to calculate the standard deviation in Java.

## 2. Calculate the Standard Deviation

Standard deviation is computed using the formula square root of ( ∑ ( Xi – ų ) ^ 2 ) / N, where:

- ∑ is the sum of each element
- Xi is each element of the array
- ų is the mean of the elements of the array
- N is the number of elements

We can easily calculate the standard deviation with the help of Java's *Math* class:

```
public static double calculateStandardDeviation(double[] array) {
// get the sum of array
double sum = 0.0;
for (double i : array) {
sum += i;
}
// get the mean of array
int length = array.length;
double mean = sum / length;
// calculate the standard deviation
double standardDeviation = 0.0;
for (double num : array) {
standardDeviation += Math.pow(num - mean, 2);
}
return Math.sqrt(standardDeviation / length);
}
```

Let's test our methods:

```
double[] array = {25, 5, 45, 68, 61, 46, 24, 95};
System.out.println("List of elements: " + Arrays.toString(array));
double standardDeviation = calculateStandardDeviation(array);
System.out.format("Standard Deviation = %.6f", standardDeviation);
```

The result will look like this:

```
List of elements: [25.0, 5.0, 45.0, 68.0, 61.0, 46.0, 24.0, 95.0]
Standard Deviation = 26.732179
```

## 3. Conclusion

In this quick tutorial, we've learned how to calculate the standard deviation in Java.

As always, the example code from this article can be found over on GitHub.

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