Curve fitting - straight line

package regression;

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Functions
{
    public void printList(List<Double> list)
    {
        int listSize = list.size();

        for(int i=0;i<listSize;i++)
        {
            System.out.println("Item "+(i+1)+" : "+list.get(i));
        }
    }
    public void printList(String listName,List<Double> list)
    {
        int listSize = list.size();
        System.out.println("In "+listName+" : ");
        for(int i=0;i<listSize;i++)
        {
            System.out.println("Item "+(i+1)+" : "+list.get(i));
        }
    }
    public double sumOfList(List<Double> list)
    {
        int listSize = list.size();
        double sum = 0;
        for(int i=0;i<listSize;i++)
        {
            sum=sum+list.get(i);
        }
        return sum;
    }
    public List<Double> makeSumOfSquareList(List<Double> list)
    {
        List<Double> newList = new ArrayList();
        int listSize = list.size();
        for(int i=0;i<listSize;i++)
        {
            double x = list.get(i);
            double newX = Math.pow(x,2);
            newList.add(newX);
        }
        return newList;
    }
        public double calculateB(List<Double> xList,List<Double> yList,int n)
    {
        double b = 0;
        double sumXY=0,sumXsumY=0,sumXsquare=0,squareOfsumX=0;
        List<Double> customList = new ArrayList();
        for(int i=0;i<n;i++)
        {
            double u = xList.get(i);
            double v = yList.get(i);
            double w = u*v;
            customList.add(w);
        }
        sumXY= sumOfList(customList);
        double x1 = sumOfList(xList);
        double x2 = sumOfList(yList);
        sumXsumY=x1*x2;
        sumXsquare=sumOfList(makeSumOfSquareList(xList));
        squareOfsumX=Math.pow(sumOfList(xList),2);

        b = ( (n*sumXY) - sumXsumY ) / ( (n*sumXsquare ) - (squareOfsumX) ) ;

        return b;
    }
    public double calculateA(List<Double> xList,List<Double> yList,int n)
    {
        double A = 0;

        double sumY = sumOfList(yList);
        double sumX = sumOfList(xList);
        double B = calculateB(xList,yList,n);

        A= ( sumY/n ) - ( ( B*sumX ) / n );

        return A;
    }
}

public class Main
{
    public static List<Double> listX = new ArrayList();
    public static List<Double> listY = new ArrayList();
    public static void inputData2D(int totalDataSize)
    {
       Scanner scanner = new Scanner(System.in);
       for(int i=0;i<totalDataSize;i++)
       {
           System.out.print("Enter x"+(i+1)+" : ");
           double x = scanner.nextDouble();
           listX.add(x);
           System.out.print("Enter y"+(i+1)+" : ");
           double y = scanner.nextDouble();
           listY.add(y);
       }

    }
    public static void main(String[] args)
    {
       Functions functions = new Functions();
       Scanner scanner = new Scanner(System.in);
       System.out.print("How many (x,y) inputs : ");
       int totalData = scanner.nextInt();
       inputData2D(totalData);
       double b = functions.calculateB(listX, listY, totalData);
       double a = functions.calculateA(listX, listY, totalData);
       System.out.println("The straight line is : y="+a+"+"+b+"x");
    }
}