TrianglePJ_Triangle_Model

package it.cefi.model;

import java.awt.GridLayout;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import it.cefi.model.Triangle;

@SuppressWarnings("serial")
public class Frame extends JFrame {

    public String pattern = "[0-9]+(\\.[0-9]+)?";

    public Frame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JFrame mainFrame = new JFrame("Triangle Checker");
        mainFrame.setLayout(new BoxLayout(mainFrame.getContentPane(), BoxLayout.PAGE_AXIS));

        JPanel upperPanel = new JPanel(new GridLayout(0, 2));
        JLabel sideA = new JLabel("Side A");
        JTextField textA = new JTextField();
        JLabel sideB = new JLabel("Side B");
        JTextField textB = new JTextField();
        JLabel sideC = new JLabel("Side C");
        JTextField textC = new JTextField();

        upperPanel.add(sideA);
        upperPanel.add(textA);
        upperPanel.add(sideB);
        upperPanel.add(textB);
        upperPanel.add(sideC);
        upperPanel.add(textC);
        mainFrame.add(upperPanel);

        JPanel lowerPanel = new JPanel();
        JButton checker = new JButton("Check!");

        lowerPanel.add(checker);
        mainFrame.add(lowerPanel);

        mainFrame.setLocationRelativeTo(null);
        mainFrame.setSize(300, 150);
        mainFrame.setResizable(false);
        mainFrame.setVisible(true);

        checker.addActionListener(e -> {

            if (textA.getText().matches(pattern) && textB.getText().matches(pattern)&& textC.getText().matches(pattern)) {
                if (Double.parseDouble(textA.getText()) > 0 && Double.parseDouble(textB.getText()) > 0
                        && Double.parseDouble(textC.getText()) > 0) {

                    Triangle triangle = new Triangle(Double.parseDouble(textA.getText()),
                            Double.parseDouble(textB.getText()), Double.parseDouble(textC.getText()));

                    if (triangle.isEquilatero())
                        JOptionPane.showMessageDialog(mainFrame, "E' Equilatero!");
                    else if (triangle.isIsoscele())
                        JOptionPane.showMessageDialog(mainFrame, "E' Isoscele!");
                    else if (triangle.isScaleno())
                        JOptionPane.showMessageDialog(mainFrame, "E' Scaleno!");
                    else
                        JOptionPane.showMessageDialog(mainFrame, "E che cos'è!?");

                }

            } else {
                JOptionPane.showMessageDialog(mainFrame,
                        "Inserisci solo valori numerici positivi, anche decimali utilizzando l'apposito \".\" ");
                textA.setText(null);
                textB.setText(null);
                textC.setText(null);
            }

        });

    }

}