201772020113 李清华《面向对象程序设计（java）》第十五周学习总结

1、实验目的与要求

(1) 掌握Java应用程序的打包操作；

(2) 了解应用程序存储配置信息的两种方法；

(3) 掌握基于JNLP协议的java Web Start应用程序的发布方法；

(5) 掌握Java GUI 编程技术。

2、实验内容和步骤

实验1： 导入第13章示例程序，测试程序并进行代码注释。

测试程序1

l  在elipse IDE中调试运行教材585页程序13-1，结合程序运行结果理解程序；

l  将所生成的JAR文件移到另外一个不同的目录中，再运行该归档文件，以便确认程序是从JAR文件中，而不是从当前目录中读取的资源。

 package resource;

 import java.awt.*;
 import java.io.*;
 import java.net.*;
 import java.util.*;
 import javax.swing.*;

 /**
  * @version 1.41 2015-06-12
  * @author Cay Horstmann
  */
 public class ResourceTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          JFrame frame = new ResourceTestFrame();
          frame.setTitle("ResourceTest");
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 /**
  * 一个加载图像和文本资源的框架。
  */
 class ResourceTestFrame extends JFrame
 {
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 300;

    public ResourceTestFrame()
    {
       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
       //获取资源文件
       URL aboutURL = getClass().getResource("about.gif");
       Image img = new ImageIcon(aboutURL).getImage();
       setIconImage(img);

       JTextArea textArea = new JTextArea();
       //从当前class下面的路径找文件
       InputStream stream = getClass().getResourceAsStream("about.txt");
       //这几句没理解
       try (Scanner in = new Scanner(stream, "UTF-8"))
       {
          while (in.hasNext())
             textArea.append(in.nextLine() + "\n");
       }
       add(textArea);
    }
 }

把JAR文件移动至桌面后运行：

l  掌握创建JAR文件的方法；

有两种：1.在CMD：

2.用集成开发环境：

右键包->选择导出->Jar文件->照提示下一步即可

测试程序2

l  在elipse IDE中调试运行教材583页-584程序13-2，结合程序运行结果理解程序；

l  了解Properties类中常用的方法；

 package properties;

 import java.awt.EventQueue;
 import java.awt.event.*;
 import java.io.*;
 import java.util.Properties;

 import javax.swing.*;

 /**
  * 一个测试属性的程序。程序记住帧的位置、大小
  * 和标题。
  * @version 1.01 2015-06-16
  * @author Cay Horstmann
  */
 public class PropertiesTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          PropertiesFrame frame = new PropertiesFrame();
          frame.setVisible(true);
       });
    }
 }

 /**
  * 从属性文件和更新恢复位置和大小的框架。
  * 退出时的属性。
  */
 class PropertiesFrame extends JFrame
 {
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;

    private File propertiesFile;
    private Properties settings;

    public PropertiesFrame()
    {
       // 从属性获取位置、大小、标题

       String userDir = System.getProperty("user.home");
       File propertiesDir = new File(userDir, ".corejava");
       if (!propertiesDir.exists()) propertiesDir.mkdir();
       propertiesFile = new File(propertiesDir, "program.properties");

       Properties defaultSettings = new Properties();
       defaultSettings.setProperty("left", "0");
       defaultSettings.setProperty("top", "0");
       defaultSettings.setProperty("width", "" + DEFAULT_WIDTH);
       defaultSettings.setProperty("height", "" + DEFAULT_HEIGHT);
       defaultSettings.setProperty("title", "");

       settings = new Properties(defaultSettings);

       if (propertiesFile.exists())
          try (InputStream in = new FileInputStream(propertiesFile))
          {
             settings.load(in);
          }
          catch (IOException ex)
          {
             ex.printStackTrace();
          }

       int left = Integer.parseInt(settings.getProperty("left"));
       int top = Integer.parseInt(settings.getProperty("top"));
       int width = Integer.parseInt(settings.getProperty("width"));
       int height = Integer.parseInt(settings.getProperty("height"));
       setBounds(left, top, width, height);

       // 如果没有标题，请询问用户

       String title = settings.getProperty("title");
       if (title.equals(""))
          title = JOptionPane.showInputDialog("Please supply a frame title:");
       if (title == null) title = "";
       setTitle(title);
       //给窗口注册一个事件监听器
       addWindowListener(new WindowAdapter()
       {
          public void windowClosing(WindowEvent event)
          {
             settings.setProperty("left", "" + getX());
             settings.setProperty("top", "" + getY());
             settings.setProperty("width", "" + getWidth());
             settings.setProperty("height", "" + getHeight());
             settings.setProperty("title", getTitle());
             try (OutputStream out = new FileOutputStream(propertiesFile))
             {
                settings.store(out, "Program Properties");
             }
             catch (IOException ex)
             {
                ex.printStackTrace();
             }
             System.exit(0);
          }
       });
    }
 }

测试程序3

l  在elipse IDE中调试运行教材593页-594程序13-3，结合程序运行结果理解程序；

l  了解Preferences类中常用的方法；

 package preferences;

 import java.awt.*;
 import java.io.*;
 import java.util.prefs.*;

 import javax.swing.*;
 import javax.swing.filechooser.*;

 /**
  * A program to test preference settings. The program remembers the frame
  * position, size, and title.
  * @version 1.03 2015-06-12
  * @author Cay Horstmann
  */
 public class PreferencesTest
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() -> {
          PreferencesFrame frame = new PreferencesFrame();
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          frame.setVisible(true);
       });
    }
 }

 /**
  * A frame that restores position and size from user preferences and updates the
  * preferences upon exit.
  */
 class PreferencesFrame extends JFrame
 {
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 200;
    private Preferences root = Preferences.userRoot();
    private Preferences node = root.node("/com/horstmann/corejava");

    public PreferencesFrame()
    {
       // 从偏好获得位置、大小、标题

       int left = node.getInt("left", 0);
       int top = node.getInt("top", 0);
       int width = node.getInt("width", DEFAULT_WIDTH);
       int height = node.getInt("height", DEFAULT_HEIGHT);
       setBounds(left, top, width, height);

       // 如果没有标题，请询问用户

       String title = node.get("title", "");
       if (title.equals(""))
          title = JOptionPane.showInputDialog("Please supply a frame title:");
       if (title == null) title = "";
       setTitle(title);

       // 设置显示XML文件的文件选择器

       final JFileChooser chooser = new JFileChooser();
       chooser.setCurrentDirectory(new File("."));
       chooser.setFileFilter(new FileNameExtensionFilter("XML files", "xml"));

       // 设置菜单

       JMenuBar menuBar = new JMenuBar();
       setJMenuBar(menuBar);
       JMenu menu = new JMenu("File");
       menuBar.add(menu);

       JMenuItem exportItem = new JMenuItem("Export preferences");
       menu.add(exportItem);
       exportItem
             .addActionListener(event -> {
                if (chooser.showSaveDialog(PreferencesFrame.this) == JFileChooser.APPROVE_OPTION)
                {
                   try
                   {
                      savePreferences();
                      OutputStream out = new FileOutputStream(chooser
                            .getSelectedFile());
                      node.exportSubtree(out);
                      out.close();
                   }
                   catch (Exception e)
                   {
                      e.printStackTrace();
                   }
                }
             });

       JMenuItem importItem = new JMenuItem("Import preferences");
       menu.add(importItem);
       importItem
             .addActionListener(event -> {
                if (chooser.showOpenDialog(PreferencesFrame.this) == JFileChooser.APPROVE_OPTION)
                {
                   try
                   {
                      InputStream in = new FileInputStream(chooser
                            .getSelectedFile());
                      Preferences.importPreferences(in);
                      in.close();
                   }
                   catch (Exception e)
                   {
                      e.printStackTrace();
                   }
                }
             });

       JMenuItem exitItem = new JMenuItem("Exit");
       menu.add(exitItem);
       exitItem.addActionListener(event -> {
          savePreferences();
          System.exit(0);
       });
    }

    public void savePreferences()
    {
       node.putInt("left", getX());
       node.putInt("top", getY());
       node.putInt("width", getWidth());
       node.putInt("height", getHeight());
       node.put("title", getTitle());
    }
 }

测试程序4

l  在elipse IDE中调试运行教材619页-622程序13-6，结合程序运行结果理解程序；

l  掌握基于JNLP协议的java Web Start应用程序的发布方法。

 package webstart;

 import java.awt.*;
 import javax.swing.*;

 /**
  * A calculator with a calculation history that can be deployed as a Java Web Start application.
  * @version 1.04 2015-06-12
  * @author Cay Horstmann
  */
 public class Calculator
 {
    public static void main(String[] args)
    {
       EventQueue.invokeLater(() ->             {
                CalculatorFrame frame = new CalculatorFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
          });
    }
 }

 package webstart;

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

 /**
    A panel with calculator buttons and a result display.
 */
 public class CalculatorPanel extends JPanel
 {
    private JTextArea display;
    private JPanel panel;
    private double result;
    private String lastCommand;
    private boolean start;

    /**
       Lays out the panel.
    */
    public CalculatorPanel()
    {
       setLayout(new BorderLayout());

       result = 0;
       lastCommand = "=";
       start = true;

       // add the display

       display = new JTextArea(10, 20);

       add(new JScrollPane(display), BorderLayout.NORTH);

       ActionListener insert = new InsertAction();
       ActionListener command = new CommandAction();

       // add the buttons in a 4 x 4 grid

       panel = new JPanel();
       panel.setLayout(new GridLayout(4, 4));

       addButton("7", insert);
       addButton("8", insert);
       addButton("9", insert);
       addButton("/", command);

       addButton("4", insert);
       addButton("5", insert);
       addButton("6", insert);
       addButton("*", command);

       addButton("1", insert);
       addButton("2", insert);
       addButton("3", insert);
       addButton("-", command);

       addButton("0", insert);
       addButton(".", insert);
       addButton("=", command);
       addButton("+", command);

       add(panel, BorderLayout.CENTER);
    }

    /**
       Gets the history text.
       @return the calculator history
    */
    public String getText()
    {
       return display.getText();
    }

    /**
       Appends a string to the history text.
       @param s the string to append
    */
    public void append(String s)
    {
       display.append(s);
    }

    /**
       Adds a button to the center panel.
       @param label the button label
       @param listener the button listener
    */
    private void addButton(String label, ActionListener listener)
    {
       JButton button = new JButton(label);
       button.addActionListener(listener);
       panel.add(button);
    }

    /**
       This action inserts the button action string to the
       end of the display text.
    */
    private class InsertAction implements ActionListener
    {
       public void actionPerformed(ActionEvent event)
       {
          String input = event.getActionCommand();
          start = false;
          display.append(input);
       }
    }

    /**
       This action executes the command that the button
       action string denotes.
    */
    private class CommandAction implements ActionListener
    {
       public void actionPerformed(ActionEvent event)
       {
          String command = event.getActionCommand();

          if (start)
          {
             if (command.equals("-"))
             {
                display.append(command);
                start = false;
             }
             else
                lastCommand = command;
          }
          else
          {
             try
             {
                int lines = display.getLineCount();
                int lineStart = display.getLineStartOffset(lines - 1);
                int lineEnd = display.getLineEndOffset(lines - 1);
                String value = display.getText(lineStart, lineEnd - lineStart);
                display.append(" ");
                display.append(command);
                calculate(Double.parseDouble(value));
                if (command.equals("="))
                   display.append("\n" + result);
                lastCommand = command;
                display.append("\n");
                start = true;
             }
             catch (BadLocationException e)
             {
                e.printStackTrace();
             }
          }
       }
    }

    /**
       Carries out the pending calculation.
       @param x the value to be accumulated with the prior result.
    */
    public void calculate(double x)
    {
       if (lastCommand.equals("+")) result += x;
       else if (lastCommand.equals("-")) result -= x;
       else if (lastCommand.equals("*")) result *= x;
       else if (lastCommand.equals("/")) result /= x;
       else if (lastCommand.equals("=")) result = x;
    }
 }

 package webstart;

 import java.io.BufferedReader;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.io.PrintStream;
 import java.net.MalformedURLException;
 import java.net.URL;

 //import javax.jnlp.BasicService;
 //import javax.jnlp.FileContents;
 //import javax.jnlp.FileOpenService;
 //import javax.jnlp.FileSaveService;
 //import javax.jnlp.PersistenceService;
 //import javax.jnlp.ServiceManager;
 //import javax.jnlp.UnavailableServiceException;
 import javax.swing.JFrame;
 import javax.swing.JMenu;
 import javax.swing.JMenuBar;
 import javax.swing.JMenuItem;
 import javax.swing.JOptionPane;

 /**
  * A frame with a calculator panel and a menu to load and save the calculator history.
  */
 public class CalculatorFrame extends JFrame
 {
    private CalculatorPanel panel;

    public CalculatorFrame()
    {
       setTitle();
       panel = new CalculatorPanel();
       add(panel);

       JMenu fileMenu = new JMenu("File");
       JMenuBar menuBar = new JMenuBar();
       menuBar.add(fileMenu);
       setJMenuBar(menuBar);

       JMenuItem openItem = fileMenu.add("Open");
       openItem.addActionListener(event -> open());
       JMenuItem saveItem = fileMenu.add("Save");
       saveItem.addActionListener(event -> save());

       pack();
    }

    /**
     * Gets the title from the persistent store or asks the user for the title if there is no prior
     * entry.
     */
    public void setTitle()
    {
       try
       {
          String title = null;

          BasicService basic = (BasicService) ServiceManager.lookup("javax.jnlp.BasicService");
          URL codeBase = basic.getCodeBase();

          PersistenceService service = (PersistenceService) ServiceManager
                .lookup("javax.jnlp.PersistenceService");
          URL key = new URL(codeBase, "title");

          try
          {
             FileContents contents = service.get(key);
             InputStream in = contents.getInputStream();
             BufferedReader reader = new BufferedReader(new InputStreamReader(in));
             title = reader.readLine();
          }
          catch (FileNotFoundException e)
          {
             title = JOptionPane.showInputDialog("Please supply a frame title:");
             if (title == null) return;

             service.create(key, 100);
             FileContents contents = service.get(key);
             OutputStream out = contents.getOutputStream(true);
             PrintStream printOut = new PrintStream(out);
             printOut.print(title);
          }
          setTitle(title);
       }
       catch (UnavailableServiceException | IOException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
    }

    /**
     * Opens a history file and updates the display.
     */
    public void open()
    {
       try
       {
          FileOpenService service = (FileOpenService) ServiceManager
                .lookup("javax.jnlp.FileOpenService");
          FileContents contents = service.openFileDialog(".", new String[] { "txt" });

          JOptionPane.showMessageDialog(this, contents.getName());
          if (contents != null)
          {
             InputStream in = contents.getInputStream();
             BufferedReader reader = new BufferedReader(new InputStreamReader(in));
             String line;
             while ((line = reader.readLine()) != null)
             {
                panel.append(line);
                panel.append("\n");
             }
          }
       }
       catch (UnavailableServiceException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
       catch (IOException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
    }

    /**
     * Saves the calculator history to a file.
     */
    public void save()
    {
       try
       {
          ByteArrayOutputStream out = new ByteArrayOutputStream();
          PrintStream printOut = new PrintStream(out);
          printOut.print(panel.getText());
          InputStream data = new ByteArrayInputStream(out.toByteArray());
          FileSaveService service = (FileSaveService) ServiceManager
                .lookup("javax.jnlp.FileSaveService");
          service.saveFileDialog(".", new String[] { "txt" }, data, "calc.txt");
       }
       catch (UnavailableServiceException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
       catch (IOException e)
       {
          JOptionPane.showMessageDialog(this, e);
       }
    }
 }

这个程序没理解

实验2：GUI综合编程练习

按实验十四分组名单，组内讨论完成以下编程任务：

练习1：采用GUI界面设计以下程序，并进行部署与发布：

l  编制一个程序，将身份证号.txt 中的信息读入到内存中；

l  按姓名字典序输出人员信息；

l  查询最大年龄的人员信息；

l  查询最小年龄人员信息；

l  输入你的年龄，查询身份证号.txt中年龄与你最近人的姓名、身份证号、年龄、性别和出生地；

l  查询人员中是否有你的同乡。

l  输入身份证信息，查询所提供身份证号的人员信息，要求输入一个身份证数字时，查询界面就显示满足查询条件的查询结果，且随着输入的数字的增多，查询匹配的范围逐渐缩小。

 package practise1;

 import java.awt.*;
 import javax.swing.*;

 public class ButtonTest {
     public static void main(String[] args) {
         EventQueue.invokeLater(() -> {
             JFrame frame = new Main();
             frame.setTitle("身份证");
             frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
             frame.setVisible(true);
         });
     }
 }

 package practise1;

 public class Student implements Comparable<Student> {

     private String name;
     private String number ;
     private String sex ;
     private int age;
     private String province;

     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getnumber() {
         return number;
     }
     public void setnumber(String number) {
         this.number = number;
     }
     public String getsex() {
         return sex ;
     }
     public void setsex(String sex ) {
         this.sex =sex ;
     }
     public int getage() {

         return age;
         }
         public void setage(int age) {
             // int a = Integer.parseInt(age);
         this.age= age;
         }

     public String getprovince() {
         return province;
     }
     public void setprovince(String province) {
         this.province=province ;
     }

     public int compareTo(Student o) {
        return this.name.compareTo(o.getName());
     }

     public String toString() {
         return  name+"\t"+sex+"\t"+age+"\t"+number+"\t"+province+"\n";
     }
 }

 package practise1;

 import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.InputStreamReader;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.Scanner;
 import java.awt.*;
 import javax.swing.*;
 import java.awt.event.*;

 public class Main extends JFrame {
     private static ArrayList<Student> studentlist;
     private static ArrayList<Student> list;
     private JPanel panel;
     private JPanel buttonPanel;
     private static final int DEFAULT_WITH = 600;
     private static final int DEFAULT_HEIGHT = 300;

     public Main() {
         studentlist = new ArrayList<>();
         Scanner scanner = new Scanner(System.in);
         File file = new File("身份证号.txt");
         try {
             FileInputStream fis = new FileInputStream(file);
             BufferedReader in = new BufferedReader(new InputStreamReader(fis));
             String temp = null;
             while ((temp = in.readLine()) != null) {

                 Scanner linescanner = new Scanner(temp);

                 linescanner.useDelimiter(" ");
                 String name = linescanner.next();
                 String number = linescanner.next();
                 String sex = linescanner.next();
                 String age = linescanner.next();
                 String province = linescanner.nextLine();
                 Student student = new Student();
                 student.setName(name);
                 student.setnumber(number);
                 student.setsex(sex);
                 int a = Integer.parseInt(age);
                 student.setage(a);
                 student.setprovince(province);
                 studentlist.add(student);

             }
         } catch (FileNotFoundException e) {
             System.out.println("学生信息文件找不到");
             e.printStackTrace();
         } catch (IOException e) {
             System.out.println("学生信息文件读取错误");
             e.printStackTrace();
         }
         panel = new JPanel();
         panel.setLayout(new BorderLayout());
         JTextArea jt = new JTextArea();
         panel.add(jt);
         add(panel, BorderLayout.NORTH);
         buttonPanel = new JPanel();
         buttonPanel.setLayout(new GridLayout(1, 7));
         JButton jButton = new JButton("字典排序");
         JButton jButton1 = new JButton("年龄最大和年龄最小");
         JLabel lab = new JLabel("猜猜你的老乡");
         JTextField jt1 = new JTextField();
         JLabel lab1 = new JLabel("找找同龄人（年龄相近）：");
         JTextField jt2 = new JTextField();
         JLabel lab2 = new JLabel("输入你的身份证号码：");
         JTextField jt3 = new JTextField();
         JButton jButton2 = new JButton("退出");
         jButton.setBounds(110, 90, 60, 30);
         jButton1.setBounds(110, 90, 60, 30);
         jt1.setBounds(110, 90, 60, 30);
         jt2.setBounds(110, 90, 60, 30);
         jt3.setBounds(110, 90, 60, 30);
         jButton2.setBounds(110, 90, 60, 30);
         jButton.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 Collections.sort(studentlist);
                 jt.setText(studentlist.toString());
             }
         });
         jButton1.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 int max = 0, min = 100;
                 int j, k1 = 0, k2 = 0;
                 for (int i = 1; i < studentlist.size(); i++) {
                     j = studentlist.get(i).getage();
                     if (j > max) {
                         max = j;
                         k1 = i;
                     }
                     if (j < min) {
                         min = j;
                         k2 = i;
                     }

                 }
                 jt.setText("年龄最大：" + studentlist.get(k1) + "年龄最小：" + studentlist.get(k2));
             }
         });
         jButton2.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 dispose();
                 System.exit(0);
             }
         });
         jt1.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 String find = jt1.getText();
                 String text="";
                 String place = find.substring(0, 3);
                 for (int i = 0; i < studentlist.size(); i++) {
                     if (studentlist.get(i).getprovince().substring(1, 4).equals(place)) {
                         text+="\n"+studentlist.get(i);
                         jt.setText("老乡：" + text);
                     }
                 }
             }
         });
         jt2.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 String yourage = jt2.getText();
                 int a = Integer.parseInt(yourage);
                 int near = agenear(a);
                 int value = a - studentlist.get(near).getage();
                 jt.setText("年龄相近：" + studentlist.get(near));
             }
         });
         jt3.addActionListener(new ActionListener() {
             public void actionPerformed(ActionEvent e) {
                 list = new ArrayList<>();
                 Collections.sort(studentlist);
                 String key = jt3.getText();
                 for (int i = 1; i < studentlist.size(); i++) {
                     if (studentlist.get(i).getnumber().contains(key)) {
                         list.add(studentlist.get(i));
                         jt.setText("emmm！你可能是：\n" + list);
                         //System.out.println("可能的人：" + studentlist.get(i));
                         //jt.setText("可能的人：" + studentlist.get(i));
                     }
                 }
             }
         });
         buttonPanel.add(jButton);
         buttonPanel.add(jButton1);
         buttonPanel.add(lab);
         buttonPanel.add(jt1);
         buttonPanel.add(lab1);
         buttonPanel.add(jt2);
         buttonPanel.add(lab2);
         buttonPanel.add(jt3);
         buttonPanel.add(jButton2);
         add(buttonPanel, BorderLayout.SOUTH);
         setSize(DEFAULT_WITH, DEFAULT_HEIGHT);
     }

     public static int agenear(int age) {
         int min = 53, value = 0, k = 0;
         for (int i = 0; i < studentlist.size(); i++) {
             value = studentlist.get(i).getage() - age;
             if (value < 0)
                 value = -value;
             if (value < min) {
                 min = value;
                 k = i;
             }
         }
         return k;
     }

 }

练习2：采用GUI界面设计以下程序，并进行部署与发布

l  编写一个计算器类，可以完成加、减、乘、除的操作

l  利用计算机类，设计一个小学生100以内数的四则运算练习程序，由计算机随机产生10道加减乘除练习题，学生输入答案，由程序检查答案是否正确，每道题正确计10分，错误不计分，10道题测试结束后给出测试总分；

将程序中测试练习题及学生答题结果输出到文件，文件名为test.txt。