Why doesn't my MVC code doesn't do anything?

Question

First of all, I am a beginner in Java. I am learning it since 2 weeks for now, but I learnt C# before. I never heard about MVC before and currently I have a problem with it. I have to do a console based calculator in MVC (I don't really know why, i heard that MVC is for applications with UI) for a competition. I've successfully done it before for an application with UI, but I don't know how and where to handle the console input and output. Currently I have the following lines of codes:

package com.kristofgero;

public class Model {
    private double e;
    public void osszead(double a, double b) {
        e = a+b;
    }
    public void kivon(double a, double b) {
        e = a-b;
    }
    public void szoroz(double a, double b) {
        e = a*b;
    }
    public void oszt(double a, double b) {
        e = a/b;
    }
    public double getCalculationValue() {
        return e;
    }
}


package com.kristofgero;
import java.util.Scanner;

public class View {
    Scanner scanner = new Scanner(System.in);
    private double a = scanner.nextDouble();
    private double b = scanner.nextDouble();
    private double e = 0;
    public double getA() {
        return a;
    }
    public double getB() {
        return b;
    }
    public double getE() {
        return e;
    }
    void displayError(String hiba) {
        System.out.println(hiba);
    }
}

package com.kristofgero;

public class Controller {
    private View theView;
    private Model theModel;

    public Controller(View theView, Model theModel) {
        this.theView = theView;
        this.theModel = theModel;
    }
    class Calculate {
        public void calculateMethod() {
            double a = 0;
            double b = 0;
            double e = 0;
            try {
                a = theView.scanner.nextDouble();
                b = theView.scanner.nextDouble();
                String jel = theView.scanner.nextLine();
                switch (jel) {
                    case "+": e = a+b; break;
                    case "-": e = a-b; break;
                    case "*": e = a*b; break;
                    case "/": e = a/b; break;
                }
            } catch (Exception error) {
                theView.displayError("Két számot adjon meg!");
            }
        }
    }
}

package com.kristofgero;

public class Main {
    public static void main(String[] args) {
        View theView = new View();
        Model theModel = new Model();
        Controller theController = new Controller(theView, theModel);

    }
}

I have to do this calculator to read the correct operation with 2 numbers that the user has given before. Right now, my code doesn't really do anything.

Answer 1

Not sure why you put the calculateMethod in an inner class but you need to call that method in order to get input from the user.

public class Controller {
    private View theView;
    private Model theModel;

    public Controller(View theView, Model theModel) {
        this.theView = theView;
        this.theModel = theModel;
    }

        public void calculateMethod() {
            double a = 0;
            double b = 0;
            double e = 0;
            try {
                a = theView.scanner.nextDouble();
                b = theView.scanner.nextDouble();
                String jel = theView.scanner.nextLine();
                switch (jel) {
                    case "+": e = a+b; break;
                    case "-": e = a-b; break;
                    case "*": e = a*b; break;
                    case "/": e = a/b; break;
                }
            } catch (Exception error) {
                theView.displayError("Két számot adjon meg!");
            }
        }
}

public class Main {
    public static void main(String[] args) {
        View theView = new View();
        Model theModel = new Model();
        Controller theController = new Controller(theView, theModel);
        theController.calculateMethod();
    }
}