/*
    Ch06Ex01.java
    CIS 160
    David Klick
    2011-09-24

    Demonstrates a working GUI (answer to Chapter 6, Exercise 1)
*/

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

public class Ch06Ex01 extends JFrame {
    JTextField txtScr1, txtScr2, txtScr3, txtScr4;
    JTextField txtWgt1, txtWgt2, txtWgt3, txtWgt4;
    
    public Ch06Ex01() {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
    
    private void createAndShowGUI() {
        final int CENTER = SwingConstants.CENTER;
        JButton btnExit = new JButton("Exit");
        JButton btnCalc = new JButton("Calc");
        
        setTitle("Chapter 6, Exercise 1");
        setSize(200,250);
        Container c = getContentPane();
        c.setLayout(new GridLayout(6,3));
        c.add(new JLabel("Test #", CENTER));
        c.add(new JLabel("Score", CENTER));
        c.add(new JLabel("Weight", CENTER));
        c.add(new JLabel("1", CENTER));
        txtScr1 = new JTextField(10);
        txtWgt1 = new JTextField(10);
        c.add(txtScr1);
        c.add(txtWgt1);
        c.add(new JLabel("2", CENTER));
        txtScr2 = new JTextField(10);
        txtWgt2 = new JTextField(10);
        c.add(txtScr2);
        c.add(txtWgt2);
        c.add(new JLabel("3", CENTER));
        txtScr3 = new JTextField(10);
        txtWgt3 = new JTextField(10);
        c.add(txtScr3);
        c.add(txtWgt3);
        c.add(new JLabel("4", CENTER));
        txtScr4 = new JTextField(10);
        txtWgt4 = new JTextField(10);
        c.add(txtScr4);
        c.add(txtWgt4);
        c.add(new JLabel());
        c.add(btnCalc);
        c.add(btnExit);
        btnCalc.addActionListener(new CalcListener());
        btnExit.addActionListener(new ExitListener());
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args) {
        Ch06Ex01 app = new Ch06Ex01();
    }

    public class ExitListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            System.exit(0);
        }
    }
    
    public class CalcListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            // get the four weightings and calc total
            double wgt1, wgt2, wgt3, wgt4, totWgt;
            wgt1 = Double.parseDouble(txtWgt1.getText());
            wgt2 = Double.parseDouble(txtWgt2.getText());
            wgt3 = Double.parseDouble(txtWgt3.getText());
            wgt4 = Double.parseDouble(txtWgt4.getText());
            totWgt = wgt1 + wgt2 + wgt3 + wgt4;

            // convert weightings to percent of total
            wgt1 /= totWgt;
            wgt2 /= totWgt;
            wgt3 /= totWgt;
            wgt4 /= totWgt;

            // get scores
            double scr1, scr2, scr3, scr4;
            scr1 = Double.parseDouble(txtScr1.getText());
            scr2 = Double.parseDouble(txtScr2.getText());
            scr3 = Double.parseDouble(txtScr3.getText());
            scr4 = Double.parseDouble(txtScr4.getText());

            // compute weighted average
            double wavg = scr1*wgt1 + scr2*wgt2 + scr3*wgt3 + scr4*wgt4;

            // display weighted average
            DecimalFormat twoPlaces = new DecimalFormat("##.##");
            JOptionPane.showMessageDialog(null, "The weighted average is "
                + twoPlaces.format(wavg));
        }
    }
}