import java.util.Arrays;
import java.util.OptionalDouble;
public class MyClass {
public static void main(String args[]) {
int arr[] = {1, 2, 4, 6, 8, 10, 12};
OptionalDouble od = Arrays.stream(arr).average();
System.out.println(od.getAsDouble());
}
}
/*
run:
6.142857142857143
*/