duck.java

import java.awt.*; // Using AWT's layouts
import java.awt.event.*; // Using AWT's event classes and listener interfaces
import java.math.BigDecimal;
import javax.swing.*; // Using Swing's components and container
import java.util.function.BiFunction;
// A Swing application extends from javax.swing.JFrame
/* Need Javadoc documentation here
 *
 *
 */
@SuppressWarnings("serial")
public class SwingAdder extends JFrame
{
    private JTextField tfNumber1, tfNumber2;
    private JLabel resultShow;
    private JButton btnAdd, btnClear, btnMinus, btnMultiply, btnDevide, btnMod;
    private int number1, number2, result;
    // Constructor to set up UI components and event handlers
    public SwingAdder() {
        // Swing components should be added to the content-pane of the JFrame.
        Container cp = getContentPane();
        // Set this Container to grid layout of 4 rows and 2 columns
        cp.setLayout(new GridLayout(6, 2, 10, 3));
        cp.add(new JLabel("First Number "));     // at (1, 1)
        tfNumber1 = new JTextField(10);
        tfNumber1.setHorizontalAlignment(JTextField.RIGHT);
        cp.add(tfNumber1);                       // at (1, 2)

        cp.add(new JLabel("Second Number "));
        tfNumber2 = new JTextField(10);
        tfNumber2.setHorizontalAlignment(JTextField.RIGHT);
        cp.add(tfNumber2);

        btnAdd = new JButton("+");
        cp.add(btnAdd);
        btnAdd.addActionListener(newListener((a,b) ->  a + b));

        btnClear = new JButton("CLEAR");
        cp.add(btnClear);

        btnDevide = new JButton("/");
        cp.add(btnDevide);
        btnDevide.addActionListener(newListener((a,b) -> a.doubleValue() / b.doubleValue()));

        btnMinus = new JButton("-");
        cp.add(btnMinus);
        btnMinus.addActionListener(newListener((a,b) -> a - b));

        btnMultiply = new JButton("*");
        cp.add(btnMultiply);
        btnMultiply.addActionListener(newListener((a,b) -> a * b));

        btnMod = new JButton("rem");
        cp.add(btnMod);
        btnMod.addActionListener(newListener((a,b) -> a % b));

        resultShow = new JLabel("--");
        btnClear.addActionListener(new ActionListener()
            {
                @Override
                public void actionPerformed(ActionEvent evt)
                {
                    tfNumber1.setText("");
                    tfNumber2.setText("");
                }
            });
        JLabel resultlabel = new JLabel("Result: ");
        cp.add(resultlabel);
        cp.add(resultShow);
        // for the "window-close" button
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setTitle("Swing Adder");
        setSize(300, 170);
        setVisible(true);
    }

    private int[] parseInputs() {
        try {
            number1 = Integer.parseInt(tfNumber1.getText());
            number2 = Integer.parseInt(tfNumber2.getText());
        } catch(NumberFormatException ex) {
            JOptionPane.showMessageDialog(tfNumber1.getParent(),
                                          "Please enter a valid integer, not" + ex.getMessage().split(":")[1]);
        }
        return new int[]{number1, number2};
    }

    private ActionListener newListener(BiFunction<Integer,Integer,Number> op) {
        return new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent evt) {
                int[] inputs = parseInputs();
                resultShow.setText("" + op.apply(inputs[0], inputs[1]));
            }
        };
    }

    // The entry main() method
    public static void main(String[] args) {
        // For thread safety, use the event-dispatching thread to construct UI
        javax.swing.SwingUtilities.invokeLater(new Runnable()
            {
                @Override
                public void run() {
                    new SwingAdder(); // Let the constructor do the job
                }
            });
    }
}