numberformattest.java

这个是我老师给的关于Java核心技术2的第10章的源代码。可以看看。

/**
   @version 1.12 2004-09-15
   @author Cay Horstmann
*/

import java.awt.*;
import java.awt.event.*;
import java.text.*;
import java.util.*;
import javax.swing.*;

/**
   This program demonstrates formatting numbers under
   various locales.
*/
public class NumberFormatTest
{
   public static void main(String[] args)
   {
      JFrame frame = new NumberFormatFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}

/**
   This frame contains radio buttons to select a number format,
   a combo box to pick a locale, a text field to display
   a formatted number, and a button to parse the text field
   contents.
*/
class NumberFormatFrame extends JFrame
{
   public NumberFormatFrame()
   {
      setTitle("NumberFormatTest");
      setLayout(new GridBagLayout());

      ActionListener listener = new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event) { updateDisplay(); }
         };

      JPanel p = new JPanel();
      addRadioButton(p, numberRadioButton, rbGroup, listener);
      addRadioButton(p, currencyRadioButton, rbGroup, listener);
      addRadioButton(p, percentRadioButton, rbGroup, listener);

      add(new JLabel("Locale:"), new GBC(0, 0).setAnchor(GBC.EAST));
      add(p, new GBC(1, 1));
      add(parseButton, new GBC(0, 2).setInsets(2));
      add(localeCombo, new GBC(1, 0).setAnchor(GBC.WEST));
      add(numberText, new GBC(1, 2).setFill(GBC.HORIZONTAL));
      locales = NumberFormat.getAvailableLocales();
      for (Locale loc : locales) localeCombo.addItem(loc.getDisplayName());
      localeCombo.setSelectedItem(Locale.getDefault().getDisplayName());
      currentNumber = 123456.78;
      updateDisplay();

      localeCombo.addActionListener(listener);

      parseButton.addActionListener(new
         ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               String s = numberText.getText().trim();
               try
               {
                  Number n = currentNumberFormat.parse(s);
                  if (n != null)
                  {
                     currentNumber = n.doubleValue();
                     updateDisplay();
                  }
                  else
                  {
                     numberText.setText("Parse error: " + s);
                  }
               }
               catch (ParseException e)
               {
                  numberText.setText("Parse error: " + s);
               }
            }
         });
      pack();
   }

   /**
      Adds a radio button to a container.
      @param p the container into which to place the button
      @param b the button
      @param g the button group
      @param listener the button listener
   */
   public void addRadioButton(Container p, JRadioButton b,
      ButtonGroup g, ActionListener listener)
   {
      b.setSelected(g.getButtonCount() == 0);
      b.addActionListener(listener);
      g.add(b);
      p.add(b);
   }

   /**
      Updates the display and formats the number according
      to the user settings.
   */
   public void updateDisplay()
   {
      Locale currentLocale = locales[localeCombo.getSelectedIndex()];
      currentNumberFormat = null;
      if (numberRadioButton.isSelected())
         currentNumberFormat = NumberFormat.getNumberInstance(currentLocale);
      else if (currencyRadioButton.isSelected())
         currentNumberFormat = NumberFormat.getCurrencyInstance(currentLocale);
      else if (percentRadioButton.isSelected())
         currentNumberFormat = NumberFormat.getPercentInstance(currentLocale);
      String n = currentNumberFormat.format(currentNumber);
      numberText.setText(n);
   }

   private Locale[] locales;
   private double currentNumber;
   private JComboBox localeCombo = new JComboBox();
   private JButton parseButton = new JButton("Parse");
   private JTextField numberText = new JTextField(30);
   private JRadioButton numberRadioButton = new JRadioButton("Number");
   private JRadioButton currencyRadioButton = new JRadioButton("Currency");
   private JRadioButton percentRadioButton = new JRadioButton("Percent");
   private ButtonGroup rbGroup = new ButtonGroup();
   private NumberFormat currentNumberFormat;
}