Calculator.java

import java.util.Scanner;

public class Calculator {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);
        System.out.print("Welcome to the calculator! There are 4 functions: \n" + " - add \n" + " - subtract \n"
                + " - multply \n" + " - divide \n" + " \n " + "Input the operation you wish to perform, or type 'quit' to quit: ");
        String input = in.nextLine();

        Calculator op = new Calculator();

        if (input.equals("add")) {
            double[] values = op.getValues();
            double result = op.add(values[0], values[1]);
            System.out.println(result);
        } else if(input.equals("subtract")) {
            double[] values = op.getValues();
            double result = op.subtract(values[0], values[1]);
            System.out.println(result);
        } else if(input.equals("multiply")) {
            double[] values = op.getValues();
            double result = op.multiply(values[0], values[1]);
            System.out.println(result);
        } else if(input.equals("divide")) {
            double[] values = op.getValues();
            double result = op.divide(values[0], values[1]);
            System.out.println(result);
        }
        in.close();
    }

    public double add(double num1, double num2) {
        double result = num1 + num2;
        return result;
    }

    public double subtract(double num1, double num2) {
        double result = num1 - num2;
        return result;
    }

    public double multiply(double num1, double num2) {
        double result = num1 * num2;
        return result;
    }

    public double divide(double num1, double num2) {
        double result = num1 / num2;
        return result;
    }

    public double[] getValues() {
        Scanner in = new Scanner(System.in);
        System.out.print("Input value 1: ");
        double num1 = in.nextDouble();
        System.out.print("Input value 2: ");
        double num2 = in.nextDouble();
        double input[] = {num1 , num2};
        in.close();
        return input;
    }
}