Error Message

[Bimz]

hi, im working on a calculator and im almost finished. All i need to do is add the = button's function, however this is what im strugling with. When ever the calc is run and i have the equation and i want to find the answer, e.g 3 + 7. I click the = button and nothing happens, in the background of my IDE i get lost of errors, heres my code.

public class Gui extends JFrame{
    
    public int ans;
    public String calc = "";
    public char[] number = {'0','1','2','3','4','5','6','7','8','9'};
    
    JTextField txt = new JTextField("", 30);
    
    public Gui() {
        
        setLayout(new FlowLayout());
        
        setTitle("Basic Calculator - Bimz");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(360, 130);
        setResizable(false);
        setLocationRelativeTo(null);
        
        txt.setEditable(false);
        add(txt);
        
        JButton btn0 = new JButton("0");
        add(btn0);
        
        JButton btn1 = new JButton("1");
        add(btn1);
        
        JButton btn2 = new JButton("2");
        add(btn2);
        
        JButton btn3 = new JButton("3");
        add(btn3);
        
        JButton btn4 = new JButton("4");
        add(btn4);
        
        JButton btn5 = new JButton("5");
        add(btn5);
        
        JButton btn6 = new JButton("6");
        add(btn6);
        
        JButton btn7 = new JButton("7");
        add(btn7);
        
        JButton btn8 = new JButton("8");
        add(btn8);
        
        JButton btn9 = new JButton("9");
        add(btn9);
        
        JButton btnP = new JButton("+");
        add(btnP);
        
        JButton btnM = new JButton("-");
        add(btnM);
        
        JButton btnE = new JButton("=");
        add(btnE);
        
                
        JButton btnD = new JButton("DEL");
        add(btnD);
        
        HandlerClass0 handler0 = new HandlerClass0();
        HandlerClass1 handler1 = new HandlerClass1();
        HandlerClass2 handler2 = new HandlerClass2();
        HandlerClass3 handler3 = new HandlerClass3();
        HandlerClass4 handler4 = new HandlerClass4();
        HandlerClass5 handler5 = new HandlerClass5();
        HandlerClass6 handler6 = new HandlerClass6();
        HandlerClass7 handler7 = new HandlerClass7();
        HandlerClass8 handler8 = new HandlerClass8();
        HandlerClass9 handler9 = new HandlerClass9();
        
        btn0.addActionListener(handler0);
        btn1.addActionListener(handler1);
        btn2.addActionListener(handler2);
        btn3.addActionListener(handler3);
        btn4.addActionListener(handler4);
        btn5.addActionListener(handler5);
        btn6.addActionListener(handler6);
        btn7.addActionListener(handler7);
        btn8.addActionListener(handler8);
        btn9.addActionListener(handler9);
        
        HandlerClassP handlerP = new HandlerClassP();
        HandlerClassM handlerM = new HandlerClassM();
        HandlerClassD handlerD = new HandlerClassD();
        [COLOR="#0000FF"]HandlerClassE handlerE = new HandlerClassE();[/COLOR]
        
        btnP.addActionListener(handlerP);
        btnM.addActionListener(handlerM);
        btnD.addActionListener(handlerD);
        [COLOR="#0000FF"]btnE.addActionListener(handlerE);[/COLOR]
        
        setVisible(true);
        
    }
        
       [COLOR="#0000FF"] private class HandlerClassE implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                ans = Integer.parseInt(calc);
                calc = Integer.toString(ans);
                txt.setText(calc);
                
            }
        }[/COLOR]
    
        private class HandlerClassD implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = "";
                txt.setText(calc);
                
            }
        }
    
        private class HandlerClassP implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + " + ";
                txt.setText(calc);
                
            }
        }
    
        private class HandlerClassM implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + " - ";
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass0 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[0];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass1 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[1];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass2 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[2];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass3 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[3];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass4 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[4];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass5 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[5];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass6 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[6];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass7 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[7];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass8 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[8];
                txt.setText(calc);
                
            }
        }
        
        private class HandlerClass9 implements ActionListener {
             
            public void actionPerformed(ActionEvent event) {

                calc = calc + number[9];
                txt.setText(calc);
                
            }
        }
}

the highlighted code is were im struggling i think, help is greatly appreciated.

Thank You :)

[eRaaaa]

. When ever the calc is run and i have the equation and i want to find the answer, e.g 3 + 7. I click the = button and nothing happens, in the background of my IDE i get lost of errors, heres my code.

Because ans = Integer.parseInt(calc); : calc is the whole string (3+7) that can not be parsed to an Integer! You have to split the string or use other methods like the Javascript-Engine :D But thats the wrong way!

[Bimz]

so split it into 3 differant parts, '3' '+' '7' then do the calculation based on the differant parts?