/*
    GUI10.java
    CIS 160
    David Klick
    2011-09-24

    Adding a listener to the calc button
*/

import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;

public class GUI10 extends JFrame {
    // these must be visible beyond the constructor 
    JTextField txtLength, txtWidth, txtArea, txtPerim;
 
    public GUI10() {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
    
    private void createAndShowGUI() {
        // set title, size, and close operation
        setSize(300, 200);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // create labels
        JLabel lblLength = new JLabel("Length:", JLabel.RIGHT);
        JLabel lblWidth = new JLabel("Width:", JLabel.RIGHT);
        JLabel lblArea = new JLabel("Area:", JLabel.RIGHT);
        JLabel lblPerim = new JLabel("Perimeter:", JLabel.RIGHT);

        // create textboxes
        txtLength = new JTextField(20);
        txtWidth = new JTextField(20);
        txtArea = new JTextField(20);
        txtArea.setEditable(false);
        txtPerim = new JTextField(20);
        txtPerim.setEditable(false);

        // create buttons
        JButton btnCalc = new JButton("Calc");
        JButton btnExit = new JButton("Exit");

        // add event handlers to exit button
        btnCalc.addActionListener(new MyCalcListener());
        btnExit.addActionListener(new MyExitListener());

        // add components to this frame's content pane
        Container c = getContentPane();
        c.setLayout(new GridLayout(5, 2));  // rows, columns
        c.add(lblLength);
        c.add(txtLength);
        c.add(lblWidth);
        c.add(txtWidth);
        c.add(lblArea);
        c.add(txtArea);
        c.add(lblPerim);
        c.add(txtPerim);
        c.add(btnCalc);
        c.add(btnExit);

        setVisible(true);
    }

    public class MyCalcListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            // get length and width from textboxes
            String strLength = txtLength.getText();
            double length = Double.parseDouble(strLength);
            String strWidth = txtWidth.getText();
            double width = Double.parseDouble(strWidth);

            // calculate area and perimeter
            double area = length * width;
            double perimeter = 2 * (length + width);

            // display area and perimeter
            txtArea.setText(String.format("%3.1f", area));
            txtPerim.setText(String.format("%3.1f", perimeter));
        }
    }

    public class MyExitListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    }

    public static void main(String[] args) {
        GUI10 app = new GUI10();
    }
}