converterswing.java

Java经典例程 从外国一大学计算机教授出版物下载的代码 经典

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.util.*;
import java.io.*;
import javagently.*;

class ConverterSwing extends JFrame {

  /* The Converter Program     by J M Bishop  Dec 1998
   * ---------------------     Display version July 1999
   *                           GUI version July 1999
   *                           Swing version B Worrall
   *                           and J Bishop Aug 2000
   * Keeps the exchange rates from one currency into
   * many others and enables currency exchanges to be
   * estimated.
   *
   * Illustrates the use of a customised Swing GUI.
   */

  public static void main(String[] args) throws IOException {
    int look = 0;
    if (args.length > 0)
      look = Integer.parseInt(args[0]);
    new ConverterSwing(look);
  }

  ConverterSwing (int look) throws IOException{
    try {
      switch (look) {
        case 1: UIManager.setLookAndFeel
          (UIManager.getCrossPlatformLookAndFeelClassName()); break;
        case 2: UIManager.setLookAndFeel
          (UIManager.getSystemLookAndFeelClassName()); break;
        case 3: UIManager.setLookAndFeel
          ("javax.swing.plaf.metal.MetalLookAndFeel"); break;
        case 4: UIManager.setLookAndFeel
          ("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
          break;
        case 5: UIManager.setLookAndFeel
          ("com.sun.java.swing.plaf.motif.MotifLookAndFeel"); break;
        case 6: UIManager.setLookAndFeel
          ("javax.swing.plaf.mac.MacLookAndFeel"); break;
      }
    }
    catch (Exception c) {
      System.out.println("Could not use the specified look and feel"
        + "- defaulting to cross-platform");
    }

      DataHandler data = new DataHandler ();
      data.initialise();
      data.readIn();
    // now control transfers to the user and events are handled
    // via actionPerformed and the transaction() method
  }

  class DataHandler extends JFrame
                   implements ActionListener, SwingConstants {

    JComboBox  fromChoice, toChoice;
    JTextField amountField;
    JTextArea  resultField;
    JButton    goButton;

    void initialise () {
      JPanel p = new JPanel (new BorderLayout());
      // Heading
      JLabel label = new JLabel ("Savannah Exchange",
        new ImageIcon("Elephant.gif"),CENTER);
        p.add("North", label);
        // left hand side panel
        JPanel q = new JPanel();
          q.add ("North",new JLabel ("From"));
          fromChoice = new JComboBox();
            q.add("Center",fromChoice);
          p.add ("West", q);
        // right hand side panel
        q = new JPanel();
          q.add ("North",new JLabel ("To"));
          toChoice = new JComboBox();
            q.add("Center",toChoice);
          p.add ("East",q);
        // Centre panel
        q = new JPanel(new BorderLayout());
          JPanel r = new JPanel();
            r.add(new JLabel("Amount"));
            amountField = new JTextField("1000  ");
              amountField.addActionListener(this);
              r.add(amountField);
              q.add("North",r);
            resultField = new JTextArea(8,20);
              q.add ("Center",resultField);
            goButton = new JButton ("Convert");
              goButton.addActionListener(this);
              q.add("South",goButton);
          p.add("Center",q);
      getContentPane().add(p);
      setTitle("Currency Converter");
      setSize(610,300);

      setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    }

    public void actionPerformed (ActionEvent e) {
      if (e.getSource() == goButton)
        transaction();
    }

    void transaction () {
      // First get the latest amount
      int amount = (int)
          Integer.parseInt(amountField.getText().trim());
      // The to and from rates are loaded directly from the
      // JComboBox and used to create the output
      Rates fromRate = (Rates) fromChoice.getSelectedItem();
      Rates toRate   = (Rates) toChoice.getSelectedItem();
      resultField.append(amount+" "+fromRate.country+" "+
                         fromRate.currency+
                         "\n in "+toRate.country+" "+
                         toRate.currency+"\n was "+
      Stream.format(amount/fromRate.conversion*
                    toRate.conversion,10,3)+"\n\n");
    }

    void readIn() throws IOException {
      Stream fin = new Stream ("Rates.data", Stream.READ);
      Rates rate;
      try {
        for (int i = 0; ; i++) {
          rate = new Rates();
          rate.setRate(fin);
          // Here we store the rate elements in the JComboBoxes.
          // Note that the whole rate is stored, but only the
          // elements specified in Rates' toString() method will
          // show up in the list.
          toChoice.addItem(rate);
          fromChoice.addItem(rate);
        }
       }
       catch (EOFException e) {}
       setVisible(true);
    }
  }
}