Calculator

import java.util.Scanner;
import static java.lang.System.*;

public class main
{
   public static void main(String[] args)
   {

        Scanner keyboard = new Scanner(System.in);

        int choice = 0;
        double fAnswer;
        String quadAns;
        boolean choice1;

        while(choice != 4)
        {
            choice1 = false;
            out.println("\n+-------------------------------------+\n");
            out.println("\t1) Quadratic Calculator");
            out.println("\t2) Area Calculator");
            out.println("\t3) Volume Calculator");
            out.println("\t4) Exit");

            choice = keyboard.nextInt();

            if (choice == 1)
            {
                double [] a;

                a = quadCal();
                out.println("The answer is: " + a[1] + " " + a[2]);
                choice1 = true;
            }

            else if (choice == 2)
            {

                fAnswer = areaCal();

            }

            else if(choice == 3)
            {
                fAnswer = volCal();
            }

            else if(choice == 4)
            {
                System.exit(0);
            }

            else
            {
                out.println("Error");
                choice1 = true;
            }

            if (choice1 == false) {
            out.println("The answer is: " + fAnswer);
            }

            else
            {
            }

        }

   }

   public static double[] quadCal()
   {

        Scanner keyboard = new Scanner(System.in);

        double[] quad;
        quad = new double[2];
        double a, b, c, n = 0;
            out.print("Enter the value of a: ");
            a = keyboard.nextDouble();
            out.println();
            out.print("Enter the value of b: ");
            b = keyboard.nextDouble();
            out.println();
            out.print("Enter the value of c: ");
            c = keyboard.nextDouble();
            out.println();

            quad[0] = ((b*(1-2)) + Math.sqrt((b*b) - (4*a*c)))/(2*a);
            quad[1] = ((b*(1-2)) - Math.sqrt((b*b) - (4*a*c)))/(2*a);

        return quad;
   }

   public static double areaCal()
   {

        Scanner keyboard = new Scanner(System.in);

        double a, b, area;

        out.print("Enter the value of height: ");
        a = keyboard.nextDouble();
        out.println();
        out.print("Enter the value of length: ");
        b = keyboard.nextDouble();
        out.println();

        area = a * b;

        return area;
   }

   public static double volCal()
   {

        Scanner keyboard = new Scanner(System.in);

        double a, b, c, volume;

        out.print("Enter the value of height: ");
        a = keyboard.nextDouble();
        out.println();
        out.print("Enter the value of length: ");
        b = keyboard.nextDouble();
        out.println();
        out.print("Enter the value of depth: ");
        c = keyboard.nextDouble();
        out.println();

        volume = a * b * c;

        return volume;
   }
}