Unable To Create Method That Calculates Standard Deviation Of Array

I am trying to create a method that calculates the standard deviation of array. What I want to be able to do is something like this

package standardDevaitionAndMean;
public class StandardDeviationTest {
public static void main (String[] args)
{
int [] array = {12,12,12,12,12,12,12};
standardDev = array.StandardDevation();
System.out.print(standardDev);
}
}

With something like this

package standardDevaitionAndMean;
public class StandardDeviation
{double mean1;
double standDev;
public double Mean(double ... array)
{
for(int i=0; i<array.length;i++)

[Code]...

So basically I want to be able to make an array in a class and be able to calculate its standard deviation with my method in my other class. I know the code I wrote is terrible but I just wanted to show what I am trying to do. I am kind of shaky on how arrays operate