Kvadrātvienādojums v2.1

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Kvadratvienadojums extends JFrame implements ActionListener {
    char kv = '\u00b2';
    char pm = '\u00b1';
    char s1 = '\u2081';
    char s2 = '\u2082';
    double r1, r2;
    JTextField aField = new JTextField(3);
    JTextField bField = new JTextField(3);
    JTextField cField = new JTextField(3);
    JLabel aLabel = new JLabel("A = ");
    JLabel bLabel = new JLabel("B = ");
    JLabel cLabel = new JLabel("C = ");
    JLabel paraugs = new JLabel("Paraugs: ax"+kv+pm+"bx"+pm+"c=0");
    JLabel rLabel1 = new JLabel("x"+s1+" = ");
    JLabel rLabel2 = new JLabel("x"+s2+" = ");
    JTextField rField1 = new JTextField(16);
    JTextField rField2 = new JTextField(16);
    JButton aprekinat = new JButton("Aprēķināt");
    String aString, bString, cString;
    int y, a, b, c;
    boolean ag = false;
    public Kvadratvienadojums() {
        super("Kvadrātvienādojums");
        setSize(220, 220);
        aField.addActionListener(this);
        bField.addActionListener(this);
        cField.addActionListener(this);
        aprekinat.addActionListener(this);
        GridBagLayout gridbag = new GridBagLayout();
        GridBagConstraints constraints = new GridBagConstraints();
        setLayout(gridbag);
        constraints.gridx = 0;
        constraints.gridwidth = 6;
        constraints.weighty = 10;
        gridbag.setConstraints(paraugs, constraints);
        add(paraugs);
        constraints = new GridBagConstraints();
        constraints.gridx = 0;
        constraints.weighty = 10;
        constraints.weightx = 10;
        gridbag.setConstraints(aLabel, constraints);
        add(aLabel);
        constraints = new GridBagConstraints();
        constraints.gridx = 1;
        constraints.weightx = 10;
        gridbag.setConstraints(aField, constraints);
        add(aField);
        constraints = new GridBagConstraints();
        constraints.gridx = 2;
        constraints.weightx = 10;
        gridbag.setConstraints(bLabel, constraints);
        add(bLabel);
        constraints = new GridBagConstraints();
        constraints.gridx = 3;
        constraints.weightx = 10;
        gridbag.setConstraints(bField, constraints);
        add(bField);
        constraints = new GridBagConstraints();
        constraints.gridx = 4;
        constraints.weightx = 10;
        gridbag.setConstraints(cLabel, constraints);
        add(cLabel);
        constraints = new GridBagConstraints();
        constraints.gridx = 5;
        constraints.weightx = 10;
        gridbag.setConstraints(cField, constraints);
        add(cField);
        constraints = new GridBagConstraints();
        constraints.gridx = 0;
        constraints.gridy = 2;
        constraints.gridwidth = 6;
        constraints.weighty = 10;
        gridbag.setConstraints(aprekinat, constraints);
        add(aprekinat);
        constraints = new GridBagConstraints();
        constraints.gridx = 0;
        constraints.gridy = 3;
        constraints.anchor = GridBagConstraints.EAST;
        constraints.weighty = 10;
        gridbag.setConstraints(rLabel1, constraints);
        add(rLabel1);
        constraints = new GridBagConstraints();
        constraints.gridx = 1;
        constraints.gridwidth = 5;
        constraints.anchor = GridBagConstraints.WEST;
        gridbag.setConstraints(rField1, constraints);
        add(rField1);
        constraints = new GridBagConstraints();
        constraints.gridx = 0;
        constraints.gridy = 4;
        constraints.anchor = GridBagConstraints.EAST;
        constraints.weighty = 10;
        gridbag.setConstraints(rLabel2, constraints);
        add(rLabel2);
        constraints = new GridBagConstraints();
        constraints.gridx = 1;
        constraints.gridwidth = 5;
        constraints.anchor = GridBagConstraints.WEST;
        gridbag.setConstraints(rField2, constraints);
        add(rField2);
        rField1.setEditable(false);
        rField2.setEditable(false);
    }
    public void actionPerformed(ActionEvent evt) {
        Object source = evt.getSource();
        if (source == aprekinat) {
            aString = aField.getText();
            bString = bField.getText();
            cString = cField.getText();
            try {
                a = Integer.parseInt(aString);
                b = Integer.parseInt(bString);
                c = Integer.parseInt(cString);
            }catch(Exception e){
                JOptionPane.showMessageDialog(null, "Nederīgas vērtības!");
                ag = true;
            }
            if (b > 0) {
                int x = b * 2;
                y = b - x;
            }else{
                int x = b * (-2);
                y = b + x;
            }
            int l = a * 2;
            int m = (b * b) - (4 * a * c);
            double n = Math.sqrt(m);
            double o = y - n;
            double p = y + n;
            r1 = o / l;
            r2 = p / l;
            if (Double.isNaN(r1) && Double.isNaN(r2) && ag == false) {
                JOptionPane.showMessageDialog(null, "Ar šīm vērtībām kvadrātvienādojumam nav atrisinājuma!");
            }
            else {
                String f1 = Double.toString(r1);
                String f2 = Double.toString(r2);
                rField1.setText(f1);
                rField2.setText(f2);
            }
            ag = false;
        }
    }
    public static void main(String[] args) {
        Kvadratvienadojums frame = new Kvadratvienadojums();
        frame.setVisible(true);
    }
}