exercise16_3.java

Introduction to java programming 一书中所有编程练习部分的源码

// Exercise16_3.java: Display country's flag and description.
// Descriptions are in the file
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;

public class Exercise16_3 extends JFrame implements ItemListener {
  // Declare an array of Strings for flag titles
  private String[] flagTitle = {"Canada", "China", "Denmark",
    "France", "Germany", "India", "Norway", "United Kingdom",
    "United States of America"};

  // Declare an ImageIcon array for the national flags of 9 countries
  private ImageIcon[] flagImage = new ImageIcon[9];

  // Declare an array of strings for flag descriptions
  private String[] flagDescription = new String[9];

  // Declare and create a description panel
  private DescriptionPanel descriptionPanel = new DescriptionPanel();

  // The combo list for selecting countries
  private JComboBox jcbo;

  // Base directory for the files
  String baseDirectory;

  // Main Method
  public static void main(String[] args) {
    Exercise16_3 frame = new Exercise16_3();
    frame.pack();
    frame.setTitle("Exercise16_3");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
  }

  // Default Constructor
  public Exercise16_3() {
    // Load images info flagImage array
    flagImage[0] = new ImageIcon("image/ca.gif");
    flagImage[1] = new ImageIcon("image/china.gif");
    flagImage[2] = new ImageIcon("image/denmark.gif");
    flagImage[3] = new ImageIcon("image/fr.gif");
    flagImage[4] = new ImageIcon("image/germany.gif");
    flagImage[5] = new ImageIcon("image/india.gif");
    flagImage[6] = new ImageIcon("image/norway.gif");
    flagImage[7] = new ImageIcon("image/uk.gif");
    flagImage[8] = new ImageIcon("image/us.gif");

    // Set text description
    for (int i=0; i<9; i++) {
      flagDescription[i] = getDescription(i);
    }

    // Create items into the combo box
    jcbo = new JComboBox(flagTitle);

    // Set the first country (Canada) for display
    setDisplay(0);

    // Add combo box and description panel to the list
    getContentPane().add(new JScrollPane(jcbo), BorderLayout.NORTH);
    getContentPane().add(descriptionPanel, BorderLayout.CENTER);

    // Register listener
    jcbo.addItemListener(this);
  }

  // Handle item selection
  public void itemStateChanged(ItemEvent e) {
    setDisplay(jcbo.getSelectedIndex());
  }

  // Set display information on the description panel
  public void setDisplay(int index) {
    descriptionPanel.setTitle(flagTitle[index]);
    descriptionPanel.setImageIcon(flagImage[index]);
    descriptionPanel.setDescription(flagDescription[index]);
  }

  private String getDescription(int i) {
    String result = new String();

    try {
      BufferedReader in = new BufferedReader(new FileReader(
        "text/description" + i + ".txt"));

      String line;

      while ((line = in.readLine()) != null) {
        result += line + '\n';
      }
    }
    catch (IOException ex) {
      System.out.println(ex);
    }

    return result;
  }
}

// Define a panel for displaying image and text
//class DescriptionPanel extends JPanel {
//  /** Label for displaying an image icon */
//  private JLabel jlblImage = new JLabel();
//
//  /** Label for displaying a title */
//  private JLabel jlblTitle = new JLabel();
//
//  /** Text area for displaying text */
//  private JTextArea jtaTextDescription;
//
//  /** Default constructor */
//  public DescriptionPanel() {
//    // Group image label and title label in a panel
//    JPanel panel = new JPanel();
//    panel.setLayout(new BorderLayout());
//    panel.add(jlblImage, BorderLayout.CENTER);
//    panel.add(jlblTitle, BorderLayout.SOUTH);
//
//    // Create a scroll pane to hold text area
//    JScrollPane scrollPane = new JScrollPane
//      (jtaTextDescription = new JTextArea());
//
//    // Center the title on the label
//    jlblTitle.setHorizontalAlignment(JLabel.CENTER);
//
//    // Set the font for the title and text
//    jlblTitle.setFont(new Font("SansSerif", Font.BOLD, 16));
//    jtaTextDescription.setFont(new Font("Serif", Font.PLAIN, 14));
//
//    // Set lineWrap and wrapStyleWord true for text area
//    jtaTextDescription.setLineWrap(true);
//    jtaTextDescription.setWrapStyleWord(true);
//    jtaTextDescription.setEditable(false);
//
//    // Set preferred size for the scroll pane
//    scrollPane.setPreferredSize(new Dimension(200, 100));
//
//    // Set BorderLayout for the whole panel, add panel and scrollpane
//    setLayout(new BorderLayout(5, 5));
//    add(scrollPane, BorderLayout.CENTER);
//    add(panel, BorderLayout.WEST);
//  }
//
//  /** Set the title */
//  public void setTitle(String title) {
//    jlblTitle.setText(title);
//  }
//
//  /** Set the image icon */
//  public void setImageIcon(ImageIcon icon) {
//    jlblImage.setIcon(icon);
//    Dimension dimension = new Dimension(icon.getIconWidth(),
//      icon.getIconHeight());
//    jlblImage.setPreferredSize(dimension);
//  }
//
//  /** Set the text description */
//  public void setTextDescription(String text) {
//    jtaTextDescription.setText(text);
//  }
//}