How to give roman numerals arabic value so that there is no error in java calculator?

Question

Java

Help me please. How can I make buttons with Roman symbols read with each other, and there would be no error with + - * /? One of the tasks: The calculator can work with both Arabic (1,2,3,4,5 ...) and with Roman (I,II,III,IV,V…) numerals; the calculator can only work with Arabic or Roman numerals at the same time, when the user enters a string like 3 + II, the calculator should throw an exception and stop working.

spoiler

package calculator_jm;

import java.awt.*;
import javax.swing.*;

/**
 *
 * @author Полина
 */
public class Calculator_JM {
    
  
   JButton button0 = new JButton("0");
   JButton button1 = new JButton("1");
   JButton button2 = new JButton("2");
   JButton button3 = new JButton("3");
   JButton button4 = new JButton("4");
   JButton button5 = new JButton("5");
   JButton button6 = new JButton("6");
   JButton button7 = new JButton("7");
   JButton button8 = new JButton("8");
   JButton button9 = new JButton("9");
   JButton buttonI = new JButton("I");
   JButton buttonII = new JButton("II");
   JButton buttonIII = new JButton("III");
   JButton buttonIV = new JButton("IV");
   JButton buttonV = new JButton("V");
   JButton buttonVI = new JButton("VI");
   JButton buttonVII = new JButton("VII");
   JButton buttonVIII = new JButton("VIII");
   JButton buttonIX = new JButton("IX");
   JButton buttonEqual = new JButton("=");
   JButton buttonBack = new JButton("C");
   
   JButton buttonPlus = new JButton("+");
   JButton buttonMinus = new JButton("-");
   JButton buttonMultiply = new JButton("*");
   JButton buttonDivide = new JButton("/");
   
   JPanel windowContent = new JPanel();
   JTextField displayField = new JTextField(30);
   
   
   Calculator_JM() {
      
       BorderLayout bl = new BorderLayout();
       windowContent.setLayout(bl);
       
       //менеджер расположения
       windowContent.add("North", displayField);
       displayField.setEditable(false);
       //панель с менеджером расположения
       JPanel p1 = new JPanel();
       GridLayout gl = new GridLayout(9,3);
       
       p1.setLayout(gl);
       p1.add(button1);
       p1.add(button2);
       p1.add(button3);
       p1.add(button4);
       p1.add(button5);
       p1.add(button6);
       p1.add(button7);
       p1.add(button8);
       p1.add(button9);
       p1.add(buttonI);
       p1.add(buttonII);
       p1.add(buttonIII);
       p1.add(buttonIV);
       p1.add(buttonV);
       p1.add(buttonVI);
       p1.add(buttonVII);
       p1.add(buttonVIII);
       p1.add(buttonIX);
       p1.add(button0);
       p1.add(buttonBack);
       p1.add(buttonEqual);
       
       windowContent.add("Center", p1);
       
       //кнопки для знаков
       JPanel p2 = new JPanel();
       GridLayout gl2 = new GridLayout(4,1);
       
       p2.setLayout(gl2);
       p2.add(buttonPlus);
       p2.add(buttonMinus);
       p2.add(buttonMultiply);
       p2.add(buttonDivide);
       
       //панель сместить вправо
       windowContent.add("East", p2);
       
       //создать и добавить все во фрейм
       JFrame frame = new JFrame("Calculator_JM");
       frame.setContentPane(windowContent);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       frame.setLocationRelativeTo(null);
       
       //размер окна и видимость
       frame.pack();
       frame.setVisible(true);
       
       //экземпляр слушател и регистрация
       CalculatorEngine calculatorEngine = new CalculatorEngine(this);
       
       button0.addActionListener(calculatorEngine);
       button1.addActionListener(calculatorEngine);
       button2.addActionListener(calculatorEngine);
       button3.addActionListener(calculatorEngine);
       button4.addActionListener(calculatorEngine);
       button5.addActionListener(calculatorEngine);
       button6.addActionListener(calculatorEngine);
       button7.addActionListener(calculatorEngine);
       button8.addActionListener(calculatorEngine);
       button9.addActionListener(calculatorEngine);
       buttonI.addActionListener(calculatorEngine);
       buttonII.addActionListener(calculatorEngine);
       buttonIII.addActionListener(calculatorEngine);
       buttonIV.addActionListener(calculatorEngine);
       buttonV.addActionListener(calculatorEngine);
       buttonVI.addActionListener(calculatorEngine);
       buttonVII.addActionListener(calculatorEngine);
       buttonVIII.addActionListener(calculatorEngine);
       buttonIX.addActionListener(calculatorEngine);
       
       buttonBack.addActionListener(calculatorEngine);
       buttonPlus.addActionListener(calculatorEngine);
       buttonMinus.addActionListener(calculatorEngine);
       buttonMultiply.addActionListener(calculatorEngine);
       buttonDivide.addActionListener(calculatorEngine);
       buttonEqual.addActionListener(calculatorEngine);
       
     
   }
   
        public static void main(String[] args) {
             Calculator_JM calc = new Calculator_JM();
             
            }    
   
}
--------------------------------------(новый класс)
package calculator_jm;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;

public class MyDrawingPad implements MouseMotionListener, ActionListener {

    @Override
    public void mouseDragged(MouseEvent e) {
     
    }

    @Override
    public void mouseMoved(MouseEvent e) {
        
    }

    @Override
    public void actionPerformed(ActionEvent e) {
       
    }
    
}
-----------------------------------------------------------------------
package calculator_jm;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;

/**
 *
 * @author Полина
 */
public class CalculatorEngine implements ActionListener {

    Calculator_JM parent;
    char selectedAction = ' '; //+ - * /
    int currentResult = 0;
    int roman = 1;
    String s;
    CalculatorEngine(Calculator_JM parent){
        this.parent = parent; 
    }
    
         @Override
         public void actionPerformed(ActionEvent e) {
            JButton clickedButton = (JButton) e.getSource();
            String dispFieldText = parent.displayField.getText();
            double displayValue = 0;
            if(!"".equals(dispFieldText)){
                displayValue = Double.parseDouble(dispFieldText);}
            Object src = e.getSource(); //для каждого деяствия кнопочки
            if (src == parent.buttonPlus){
                selectedAction = '+';
                currentResult = (int) displayValue;
                parent.displayField.setText(""); }
            else if (src == parent.buttonMinus){
                selectedAction = '-';
                currentResult = (int) displayValue;
                parent.displayField.setText(""); }
            else if (src == parent.buttonMultiply){
                selectedAction = '*';
                currentResult = (int) displayValue;
                parent.displayField.setText(""); }
            else if (src == parent.buttonDivide){
                selectedAction = '/';
                currentResult = (int) displayValue;
                parent.displayField.setText(""); }
            else if (src == parent.buttonBack){
                selectedAction = 'C';
                currentResult = (int) displayValue;
                parent.displayField.setText("");}
            else if (src == parent.buttonEqual){
                if (selectedAction == '+'){
                currentResult += displayValue;
                parent.displayField.setText("" + currentResult);}
                else if (selectedAction == '-'){
                currentResult -= displayValue;
                parent.displayField.setText("" + currentResult);}
                else if (selectedAction == '*'){
                currentResult *= displayValue;
                parent.displayField.setText("" + currentResult);}
                else if (selectedAction == '/'){
                currentResult /= displayValue;
                parent.displayField.setText("" + currentResult);}
                else if (selectedAction == 'C'){
                currentResult = (int) displayValue;
                parent.displayField.setText("" + currentResult);}
            } else {
                String clickedButtonLabel = clickedButton.getText();
                parent.displayField.setText(dispFieldText + clickedButtonLabel);}
           
   

}}

Answer 1

Try this

double displayValue = 0;
        if (!"".equals(dispFieldText)) {
            try {
                displayValue = Double.parseDouble(dispFieldText);
            }catch (NumberFormatException e1){
                HashMap<String,Integer> map = new HashMap<>();
                map.put("I",1);
                map.put("II",2);
                map.put("III",3);
                map.put("IV",4);
                map.put("V",5);
                map.put("VI",6);
                map.put("VII",7);
                map.put("VIII",8);
                map.put("IX",9);
                displayValue = Double.parseDouble(String.valueOf(map.get(dispFieldText)));

            }
        }
        Object src = e.getSource(); //для каждого деяствия кнопочки