Java程序设计（北京大学MOOC）

　　Java程序设计课程，使用eclipse集成开发环境 和 editpuls编辑器（java配置）

　　第一讲 Java语言与面向对象设计

　　1、Java语言，从C++发展而来，是C++的简化版，简单易学，纯面向对象，与平台无关，支持多线程，安全稳定

 　　Java拥有丰富的类库，可以面向对象的应用开发、各类网络应用程序的开发，Internet的系统管理，数据库操作等等

　　2、类是具有共同属性和行为的对象的集合，类是对象的抽象，对象是类的实例

　　第二讲　简单的Java程序

　　Java文件名要与public类的类名一致，一个文件只能有一个public类

　　applet程序（界面库 javaFx，swing(JFrame，JApplet，JPanel)，awt( 图形库graphics )）

package week1.applet;

import java.awt.Graphics;
import javax.swing.JApplet;

public class SayHelloApplet extends JApplet {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    public void paint(Graphics g){
        g.drawString("Hello World",    20, 20);
    }

}

　　命令行下设定path和classpath：set path是命令（javac及Java）的路径，set classpath是所要引用的类库的路径　　

　　编程题代码，仅供参考

　　第二讲　简单的Java程序　　

package week2;

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        /*
         * 3^3 + 4^3 + 5^3 = 6^3
        int sum = 0;
        final int first = 3;
        final int last = 5;
        final int result = 6;
        for (int x = first; x <= last; ++x) {
            sum += x * x * x;
        }
        if (sum == result * result * result)
            System.out.print("yes!");
        else
            System.out.print("No!");
        */
        
        /*
         * 6^3 + ... + 69^3 = 180^3
        int sum = 0;
        final int first = 6;
        final int last = 69;
        final int result = 180;
        for (int x = first; x <= last; ++x) {
            sum += x * x * x;
        }
        if (sum == result * result * result)
            System.out.print("yes!");
        else
            System.out.print("No!");
        */
        
        //更多的情况
        int sum = 0;
        int first = 1;
        final int last = 1000;
        for (int i = 1; i < last / 2; ++i) {
            first = i;
            sum = 0;
            for (int x = first; x <= last; ++x) {
                sum += x * x * x;
                for (int k = x + 1; k <= last; ++k) {
                    if (sum == k * k * k) {
                        System.out.printf("first=%d,...", first);
                        System.out.printf("last=%d,", x);
                        System.out.printf("result=%d
", k);
                    }
                }
            }//end of for
        }//end of for
    }//end of main
}// end of class

　　第三讲 数据运算、流控制和数组

package week3;

public class Prime {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] prime = new int[100]; // 保存素数
        boolean[] is_prime = new boolean[100]; // true表示i是素数
        int p = 0;

        for (int i = 0; i < 100; i++)// 初始化
        {
            is_prime[i] = true;
        }

        is_prime[0] = is_prime[1] = false; // 0,1不是素数

        for (int i = 2; i < 100; i++) {
            if (is_prime[i]) //
            {
                prime[p++] = i; // 计算素数的个数,也记录下了素数
                for (int j = 2 * i; j < 100; j += i)// 除掉了i的倍数的数字
                {
                    is_prime[j] = false;
                }
            }
        }

        for (int pr : prime) {
            if (pr > 0)
                System.out.print(pr + " ");
        }
    }
}

　　第四讲 类、包和接口

package week4;

//接口
interface Flyable {
    void fly();// 默认public abstract
}

// 抽象类
abstract class Anmial implements Flyable {

    @Override // 覆盖
    public void fly() {
        System.out.println("开始飞行");
        System.out.println("飞行结束");
    }
}

public class Bird extends Anmial {
    private String bird;

    // static final字段
    protected static final int distance = 100;

    // setter
    public void setter(String bird) {
        this.bird = bird;
    }

    // getter
    public String getter() {
        return bird;
    }

    // 飞翔
    @Override // 覆盖
    public void fly() {
        System.out.println(this.bird + "开始飞行");
        System.out.println("开始" + distance + "米飞行中");
        System.out.println(getter() + "飞行结束
");// 使用getter
    }

    // main函数
    public static void main(String[] args) {
        System.out.println("飞翔接力正式开始！
");

        String bir1 = "bird1";
        String bir2 = "bird2";

        Bird bird1 = new Bird();
        bird1.setter(bir1);
        bird1.fly();

        Bird bird2 = new Bird();
        bird2.setter(bir2);
        bird2.fly();

        System.out.println("飞翔接力结束！
");
    }
}

　　第五讲 深入理解Java语言 

package week5;
/**
 *  一个简单的新闻事件侦听演示程序
 * @author tds
 * @author 修改者：金色的省略号
 */

public class NewsDemo {
    public static void main(String[] args) {
        
        //模拟有一家新闻社
        NewsAgency bbc = new NewsAgency("BBC");
        //订阅该社的新闻
        bbc.addListener(new MyListener());
        
        //TODO 请在这里再加入一个Listener
        //1.匿名类
        bbc.addListener(new Listener(){
            //当接收到消息后，进行一些显示
            public void newsArrived(NewsEvent e){
                if( e.level>5) System.out.println("warning :");
                System.out.println("please note," + e.text + " happed!");
            }
        });
        //2.lambda表达式
        bbc.addListener((NewsEvent e)->
            {
                if( e.level>5) System.out.println("warning :");
                System.out.println("please note," + e.text + " happed!");
            }
        );
        
        //新闻社启动其工作流程
        bbc.start();                
    }
}


/**
 * 事件信息
 */
class NewsEvent{
    Object source;  //事件来源
    String text;    //事件内容
    int level;      //事件级别
    NewsEvent(Object source, String text, int level){
        this.source=source;
        this.text = text;
        this.level = level;        
    }
}
interface Listener{
    void newsArrived(NewsEvent e);
}

/**
 * 新闻机构
 */
class NewsAgency {
    String name; //机构名
    public NewsAgency(String name) {
        this.name = name;        
    }
    Listener[] listeners = new  Listener[100]; //侦听者（订阅者）
    int listenerCnt = 0; //已有的订阅者
    
    //加入一个订阅者
    void addListener(Listener oneListener){
        if(listenerCnt<listeners.length){
            listeners[listenerCnt] = oneListener;
            listenerCnt++;
        }        
    }
    
    //模拟一个事件发生，并通知所有的订阅者
    void start(){
        NewsEvent event = new NewsEvent("Mr. Joan", "Bombing", 9 );
        
        for(int i=0; i<listenerCnt; i++) {
            listeners[i].newsArrived(event);
        }
        
    }
}

/**
 * 实现一个订阅者
 */
class MyListener implements Listener{
    //当接收到消息后，进行一些显示
    public void newsArrived(NewsEvent e){
        if( e.level>5) System.out.println("warning :");
        System.out.println("please note," + e.text + " happed!");
    }
}

　　第六讲 异常处理

package week6;

//自定义一个异常类，继承自系统的异常类Exception
class MyException extends Exception {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    // 构造方法
    public MyException(String msg) {
        super(msg);
    }
}

// 使用自定义的异常
public class TestMyException {
    // 在一个函数中抛出异常
    public static void MyExc() throws MyException {
        throw new MyException("MyExc() method occurs an exception! ");
    }

    // 调用这个函数并捕获异常。
    public static void main(String[] args) {
        try {
            TestMyException.MyExc();
        } catch (MyException e1) {
            System.out.println("MyException: " + e1.getMessage());
            // e1.printStackTrace();//显示调用堆栈的跟踪信息
        }
    }
}

　　第七讲 工具类及常用算法

package week7;

import java.util.ArrayList;
import java.util.Scanner;

//账户类
class account {
    private String username;
    private String password;
    private double balance;

    // 构造
    public account(String _username, String _password, double _balance) {
        username = _username;
        password = _password;
        balance = _balance;
    }

    // 取款
    void withdraw(double _balance) {
        if (balance >= _balance) {
            balance -= _balance;
            System.out.println("当前余额是：" + balance);
        } else {
            System.out.println("余额不足");
        }
    }

    // 存款
    void deposit(double _balance) {
        balance += _balance;
        System.out.println("当前余额是：" + balance);
    }

    String getUsername() {
        return username;
    }

    String getUpassword() {
        return password;
    }

    double getBalance() {
        return balance;
    }
}

class Mybank {
    private String bankName;
    // 账户列表
    private ArrayList<account> arr;

    // 构造
    Mybank(String _bankName) {
        setBankName(_bankName);
        arr = new ArrayList<>();
    }

    // 开户
    void openAccount() {
        Scanner in = new Scanner(System.in);
        while (true) {
            System.out.println("请输入用户名、密码、开户金额：");
            account a = new account(in.next(), in.next(), in.nextDouble());
            arr.add(a);
            System.out.println("继续，请输入y，退出输入n");
            String s = in.next();
            if (s.equals("n"))
                break;
        }
        //in.close();  //为何不能关闭？
    }

    // 取款
    void drawAccount() {
        while (true) {
            Scanner in = new Scanner(System.in);
            System.out.println("请输入用户名、密码及取款数额:");
            String _username = in.next();
            String _password = in.next();
            double _balance = in.nextDouble();
            boolean b = true;
            for (account a : arr) {
                if (a.getUsername().equals(_username) && a.getUpassword().equals(_password)) {
                    a.withdraw(_balance);
                    b = false;
                    break;
                }
            }
            if (b)
                System.out.println("用户名或密码错误！");
            System.out.println("继续取款，请输入y，退出输入n");
            String s = in.next();
            if (s.equals("n"))
                break;
            in.close();
        }
    }

    // 存款
    void depositAccount() {
        while (true) {
            Scanner in = new Scanner(System.in);
            System.out.println("请输入用户名、密码及存款数额:");
            String _username = in.next();
            String _password = in.next();
            double _balance = in.nextDouble();
            boolean b = true;
            for (account a : arr) {
                if (a.getUsername().equals(_username) && a.getUpassword().equals(_password)) {
                    a.deposit(_balance);
                    b = false;
                    break;
                }
            }
            if (b)
                System.out.println("用户名或密码错误！");
            System.out.println("继续存款，请输入y，退出输入n");
            String s = in.next();
            if (s.equals("n"))
                break;
            in.close();
        }
    }

    // 查询
    void checkAccount() {
        while (true) {
            Scanner in = new Scanner(System.in);
            System.out.println("请输入用户名、密码:");
            String _username = in.next();
            String _password = in.next();
            boolean b = true;
            for (account a : arr) {
                if (a.getUsername().equals(_username) && a.getUpassword().equals(_password)) {
                    System.out.println("你的账户余额：" + a.getBalance());
                    b = false;
                    break;
                }
            }
            if (b)
                System.out.println("用户名或密码错误！");
            System.out.println("继续查找，请输入y，退出输入n");
            String s = in.next();
            if (s.equals("n"))
                break;
            in.close();
        }
    }

    public String getBankName() {
        return bankName;
    }

    public void setBankName(String bankName) {
        this.bankName = bankName;
    }
}

// 测试类
public class test {

    public static void main(String[] args) {
        Mybank m = new Mybank("我的银行");
        Scanner in = new Scanner(System.in);
        // 测试面板
        label: while (true) {
            System.out.println("开户请按1，存款请按2，取款请按3，" + "查询请按4，退出请按5");            
            String s = in.next();
            switch (s) {
            case "1":
                m.openAccount();
                break;
            case "2":
                m.depositAccount();
                break;
            case "3":
                m.drawAccount();
                break;
            case "4":
                m.checkAccount();
                break;
            case "5":
                break label;
            }            
        }
        in.close();
    }
}

　　第八讲 多线程

package week8;

import java.net.URL;
import java.io.*;
import java.util.Date;

class ThreadDownload 
{
    public static void main(String[] args)
            throws IOException
    {
        final URL[] urls = {
            new URL("https://www.pku.edu.cn"),
            new URL("https://www.baidu.com"),
            new URL("https://www.sina.com.cn"),
            new URL("https://www.dstang.com")
        };
        final String[] files = {
            "pku.htm", 
            "baidu.htm",
            "sina.htm", 
            "study.htm",
        };
        for(int i=0; i<urls.length; i++){
            final int idx = i;
            new Thread( ()-> {
                try{
                    System.out.println( urls[idx]);
                    download( urls[idx], files[idx]);
                }catch(Exception ex){
                    ex.printStackTrace();
                }
            }).start();    
        }
        Thread t = new MyThread();
        t.setDaemon(true);
        t.start();
    
        
        
    }
    static void download( URL url, String file)
        throws IOException
    {
        try(InputStream input = url.openStream();
            OutputStream output = new FileOutputStream(file))
        {
            byte[] data = new byte[1024];
            int length;
            while((length=input.read(data))!=-1){
                output.write(data,0,length);
            }
        }
    }
    
}

class MyThread extends Thread {
    double x;
    public void run() {    
        while(true)
        {
            x += new Date().getTime();    
            print();
        }    
    }
    public void print() {
        System.out.println(x);
    }
}

　　第九讲  流、文件及基于文本的应用

package week9;

import java.io.*;
import java.awt.*;
//import java.awt.event.*;
import javax.swing.*;
import java.util.List;
import java.util.ArrayList;

public class Recite extends JFrame {
    public Recite() {
    }
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    JLabel lblWord = new JLabel("word");
    JLabel lblMeaning = new JLabel("meaning");

    public void init() {
        setSize(400, 100);
        getContentPane().setLayout(new FlowLayout());
        getContentPane().add(lblWord);
        getContentPane().add(lblMeaning);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }

    List<String> words = new ArrayList<>();
    List<String> meanings = new ArrayList<>();
    int current = 0;

    public void start() {
        new Thread(() -> {
            try {
                readAll();
            } catch (IOException ex) {
            }
            new javax.swing.Timer(1000, (e) -> {
                lblWord.setText(words.get(current));
                lblMeaning.setText(meanings.get(current));
                current++;
            }).start();
        }).start();
    }

    public void readAll() throws IOException {
        String fileName = "College_Grade4.txt";
        String charset = "GB2312";
        BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), charset));
        String line;
        while ((line = reader.readLine()) != null) {
            line = line.trim();
            if (line.length() == 0)
                continue;
            int idx = line.indexOf("	");
            words.add(line.substring(0, idx));
            meanings.add(line.substring(idx + 1));
        }
        reader.close();
    }

    public static void main(String[] args) {
        Recite f = new Recite();
        f.init();
        f.start();
    }
}

　　College_Grade4.txt文件要放在工程目录下

　　第十讲 图形用户界面

package week10;

import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import java.awt.Dimension;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;
import java.awt.event.ActionEvent;
import java.awt.Rectangle;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JTextArea;

/**
 * @Title:BMI计算器
 * @author 金色的省略号
 * @Description:程序可以计算国际标准和国内标准BMI 体重、身高没有输入，或输入错误，会有错误提示输出
 */

public class BMI extends JFrame {

    /**
     * 
     */
    private static final long serialVersionUID = 3166024052981905555L;
    /**
     * BMI Calculator v1.001
     */
    private String DomesticStandardsBMI;
    private String internationalStandardsBMI;
    private double BMI;
    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private JTextArea textArea;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    BMI frame = new BMI();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public BMI() {
        //
        setFont(new Font("楷体", Font.BOLD, 21));
        setTitle("u4F53u91CDu6307u6570u8BA1u7B97u5668");
        setBounds(new Rectangle(200, 200, 300, 300));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 505, 321);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);
        // 身高标签
        JLabel lblNewLabel = new JLabel("u8BF7u8F93u5165u8EABu9AD8(m)");
        lblNewLabel.setFont(new Font("楷体", Font.BOLD, 18));
        lblNewLabel.setSize(new Dimension(4, 0));
        lblNewLabel.setBounds(37, 87, 182, 36);
        contentPane.add(lblNewLabel);
        // 体重标签
        JLabel lblkg = new JLabel("u8BF7u8F93u5165u4F53u91CD(kg)");
        lblkg.setFont(new Font("楷体", Font.BOLD, 18));
        lblkg.setSize(new Dimension(4, 0));
        lblkg.setBounds(37, 10, 182, 36);
        contentPane.add(lblkg);
        // TextField
        textField = new JTextField();
        textField.setBackground(Color.CYAN);
        textField.setFont(new Font("楷体", Font.BOLD, 21));
        textField.setBounds(37, 42, 420, 47);
        contentPane.add(textField);
        textField.setColumns(10);
        // textField_1
        textField_1 = new JTextField(2);
        textField_1.setBackground(Color.CYAN);
        textField_1.setFont(new Font("楷体", Font.BOLD, 21));
        textField_1.setColumns(10);
        textField_1.setBounds(37, 122, 420, 47);
        contentPane.add(textField_1);
        // 按钮btnUtton
        JButton btnUtton = new JButton("OK");
        btnUtton.setFont(new Font("楷体", Font.BOLD, 21));
        btnUtton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                // 获取BMI
                getBMI();
                // 输出BMI
                DecimalFormat df = new DecimalFormat("0.00");
                String bmi = "体质指数：" + df.format(BMI) + "
";
                if (BMI > -0.0001 && BMI < 0.0001) {
                    bmi = "";
                }
                textArea.setLineWrap(true);
                textArea.setText(DomesticStandardsBMI + " " + internationalStandardsBMI + "
" + bmi);
            }
        });
        btnUtton.setBounds(374, 193, 83, 65);
        contentPane.add(btnUtton);
        // textArea
        textArea = new JTextArea();
        textArea.setFont(new Font("楷体", Font.BOLD, 21));
        textArea.setBackground(Color.CYAN);
        textArea.setBounds(37, 193, 342, 65);
        contentPane.add(textArea);
    }

    public void getBMI() {
        // 判断输入是否正确
        String w = textField.getText();
        String h = textField_1.getText();
        if (!w.matches("^[0-9]+\.?[0-9]+$") || !h.matches("^[0-9]+[.]?[0-9]+$"))

        {
            BMI = 0.0;
            DomesticStandardsBMI = "请正确输入：";
            internationalStandardsBMI = "体重和身高。";
            return;
        }
        // 计算BMI
        double weight = Double.valueOf(textField.getText());
        double high = Double.valueOf(textField_1.getText());
        BMI = weight / Math.pow(high, 2);
        if (BMI < 18.5) {
            internationalStandardsBMI = "国际标准：偏瘦";
            DomesticStandardsBMI = "国内标准：偏瘦";
        } else if (BMI < 25) {
            internationalStandardsBMI = "国际标准：正常";
            if (BMI < 24) {
                DomesticStandardsBMI = "国内标准：正常";
            } else {
                DomesticStandardsBMI = "国内标准：偏胖";
            }
        } else if (BMI < 30) {
            internationalStandardsBMI = "国际标准：偏胖";
            if (BMI < 28) {
                DomesticStandardsBMI = "国内标准：偏胖";
            } else {
                DomesticStandardsBMI = "国内标准：肥胖";
            }
        } else {
            internationalStandardsBMI = "国际标准：肥胖";
            DomesticStandardsBMI = "国内标准：肥胖";
        }
    }
}

　　第十一讲 网络、多媒体和数据库编程

package week11;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.EmptyBorder;
import javax.swing.JLabel;
import java.awt.Dimension;
import javax.swing.JTextField;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Rectangle;
import java.awt.Font;
import java.awt.Color;
import javax.swing.JTextArea;
//MyBank
public class MyBank extends JFrame{
     
    private Bank bank = new Bank("我的银行");
    private String selectBusiness = "开户";
    private JPanel contentPane;
    private JTextField textField;
    private JTextField textField_1;
    private JTextArea textArea;
  
    public static void main(String[] args) {
          EventQueue.invokeLater(new Runnable() {
              public void run() {
                  try {
                        MyBank frame = new MyBank();
                      frame.setVisible(true);
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
     }
     
    public MyBank() {
        //
        setFont(new Font("楷体", Font.BOLD, 21));
        setTitle("银行模拟系统");
        setBounds(new Rectangle(200, 200, 300, 300));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 458, 282);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);
        //
        JLabel lblNewLabel = new JLabel("请输入密码");
        lblNewLabel.setFont(new Font("楷体", Font.BOLD, 14));
        lblNewLabel.setSize(new Dimension(4, 0));
        lblNewLabel.setBounds(216, 22, 81, 36);
        contentPane.add(lblNewLabel);
        //
        JLabel lblkg = new JLabel("请输入账号");
        lblkg.setFont(new Font("楷体", Font.BOLD, 14));
        lblkg.setSize(new Dimension(4, 0));
        lblkg.setBounds(10, 22, 81, 36);
        contentPane.add(lblkg);
        //TextField
        textField = new JTextField();
        textField.setBackground(Color.CYAN);
        textField.setFont(new Font("楷体", Font.BOLD, 21));
        textField.setBounds(92, 20, 114, 36);
        contentPane.add(textField);
        textField.setColumns(10);
        //textField_1
        textField_1 = new JTextField(2);
        textField_1.setBackground(Color.CYAN);
        textField_1.setFont(new Font("楷体", Font.BOLD, 21));
        textField_1.setColumns(10);
        textField_1.setBounds(298, 20, 114, 36);
        contentPane.add(textField_1);
         
        //按钮btnUtton
        JButton btnUtton = new JButton("OK");
        btnUtton.setFont(new Font("楷体", Font.BOLD, 21));
        btnUtton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {      
     
                String s = selectBusiness;
                String _username = textField.getText();
                String _password = textField_1.getText();    
               // textField_1.setText("******");
                double _balance = 0.0;
                String d = "";
                if(textArea.getText().matches("^\d+(\.\d+)?$")){
                    _balance = Double.valueOf(textArea.getText());
                }
                else if(!s.equals("查询")){
                    d = "请清空此栏，输入金额。";
                    s = "";
                }
                
                if(_username.equals("")
                        ||_password.equals("")){
                    d = "请正确输入账号和密码。";
                    s = "";
                }
                
                switch(s)
                {
                    case "开户":
                        d = bank.openAccount(_username,_password,_balance);
                        break;
                    case "存款":    
                        d = bank.depositAccount(_username,_password,_balance);break;
                    case "取款":             
                        d = bank.drawAccount(_username,_password,_balance);break;
                    case "查询":
                        d = bank.checkAccount(_username,_password); break;          
                    case "":
                        break;    
                }         
                textArea.setText(d); 
                
            }
        });
        btnUtton.setBounds(356, 138, 62, 46);
        contentPane.add(btnUtton); 
        //textArea  
        textArea = new JTextArea();
        textArea.setFont(new Font("楷体", Font.BOLD, 21));
        textArea.setBackground(Color.CYAN);
        textArea.setBounds(10, 141, 344, 42);
        contentPane.add(textArea);
        //
        JLabel label = new JLabel("请选择业务");
        label.setSize(new Dimension(4, 0));
        label.setFont(new Font("楷体", Font.BOLD, 14));
        label.setBounds(10, 85, 81, 36);
        contentPane.add(label);
          
        JRadioButton rdbtnNewRadioButton = new JRadioButton("开户");
        rdbtnNewRadioButton.setBounds(102, 90, 72, 23);
        contentPane.add(rdbtnNewRadioButton);    
        rdbtnNewRadioButton.setSelected(true);
        rdbtnNewRadioButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                selectBusiness = "开户"; 
            }
        });
          
          
        JRadioButton radioButton = new JRadioButton("存款");
        radioButton.setBounds(171, 90, 72, 23);
        contentPane.add(radioButton);
        radioButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                selectBusiness = "存款";
            }
        });
          
        JRadioButton radioButton_1 = new JRadioButton("取款");
        radioButton_1.setBounds(250, 90, 63, 23);
        contentPane.add(radioButton_1);
        radioButton_1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                selectBusiness = "取款";    
            }
        });
        
        JRadioButton radioButton_2 = new JRadioButton("u67E5u8BE2");
        radioButton_2.setBounds(320, 90, 62, 23);
        contentPane.add(radioButton_2);
        radioButton_2.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent arg0) {
                selectBusiness = "查询";
            }
        }); 
        //ButtonGroup本身不是控件，不能放到容器里
        ButtonGroup buttonGroup = new ButtonGroup(); 
        buttonGroup.add(radioButton);
        buttonGroup.add(radioButton_1);
        buttonGroup.add(radioButton_2);
        buttonGroup.add(rdbtnNewRadioButton);
    }     
}

package week11;

import java.util.ArrayList;

public class Bank {
      private String bankName;
        //账户列表
        private ArrayList<Account> arr;
        //构造
        Bank(String _bankName)
        {
            bankName = _bankName;
            arr = new ArrayList<>();
        }
        //开户
        String openAccount(String _username,String _password,double _balance)
        {  
            String str = "";
            boolean ok = true;
            for (Account a : arr) {
//                if(a.getUsername().equals(_username)
//                        &&a.getUpassword().equals(_password)){
                if(a.isUsername(_username)
                        &&a.isPassword(_password)){    
                    ok = false;
                    break;
                }
            }
            if(ok){
                Account a = new Account(_username,_password,_balance);
                arr.add(a);
            } 
            str = "存款余额："+_balance;
            if(!ok){
                str = "该用户已经存在。";
            }
            return str;
        }
        //取款
        String drawAccount(String _username,String _password,double _balance)
        {          
                String d = "";
                boolean b = true;
                for (Account a : arr) {
                    if(a.isUsername(_username)
                            &&a.isPassword(_password)){    
                        if(a.withdraw(_balance)){
                            d = "存款余额：" + a.getBalance();   
                        }
                        else{
                            d = "余额不足,存款余额：" + a.getBalance();
                        }
                        b=false;
                        break;
                    }
                }
                if(b)d = "用户名或密码错误！"; 
                return d;
        }
        
        //存款
        String  depositAccount(String _username,String _password,double _balance)
        {
            String d = "";
            boolean b = true;
            for (Account a : arr) {
                if(a.isUsername(_username)
                        &&a.isPassword(_password)){    
                    a.deposit(_balance);
                    d = "存款余额：" + a.getBalance();
                    b=false;
                    break;
                }
            }
            if(b)d = "用户名或密码错误！"; 
            return d;
             
        }
        //查询
        String checkAccount(String _username,String _password)
        {   
            String d = "";
            boolean b = true;
            for (Account a : arr) {
                if(a.isUsername(_username)
                        &&a.isPassword(_password)){        
                    d = "存款余额：" + a.getBalance();
                    b=false;
                    break;
                }
            }
            if(b)d = "用户名或密码错误！"; 
            return d;  
         }
}

package week11;

public class Account {
    private String username;
    private String password;
    private double balance;
    //构造
    public Account(String _username,String _password,double _balance)
    {
       username = _username;
        password = _password;
        balance = _balance;
    }
    //取款
    boolean withdraw(double _balance)
    {
        if(balance>=_balance)
        {
           balance-=_balance;
        }
        else
        {
           return false;
        }
        return true;
    }
    //存款
    void deposit(double _balance)
    {
       balance+=_balance; 
    }
    //
    double getBalance()
    {
       return balance;
    }
    //
    boolean isUsername(String str)
    {
        return username.equals(str);
    }
    //
    boolean isPassword(String str){
        return password.equals(str);
    } 
}