Java期末题库

根据如下图所示数据库信息，完成1-3小题。

（1）使用JDBC数据库连接技术，编写JDBCUtil工具类，在该类中定义getCon方法用于获得与数据库的连接对象，定义closeAll方法用于释放连接对象等资源。

import java.sql.*;public class JDBCUtil {private static String user="用户名";private static String password="密码";private static String url="jdbc:mysql://localhost:3306/数据库名";private static String driver="com.mysql.jdbc.Driver";/*** 连接数据库, 返回 Connection*/public static Connection getCon() {try {return DriverManager.getConnection(url, user, password);} catch (SQLException e) {throw new RuntimeException(e);}}/*** 关闭连接*/public static void closeAll(ResultSet set, PreparedStatement statement, Connection connection) {try {if (set != null) {set.close();}if (statement != null) {statement.close();}if (connection != null) {connection.close();}} catch (SQLException e) {throw new RuntimeException(e);}}
}

（2）应用类的封装性，创建book表对应的类，其中book表存储图书id（主键、自增）、书名、价格、作者、库存量等信息。

public class Book {private Integer id;private String name;private Double price;private String author;private Integer reserve;public Book() {}public Book(Integer id, String name, Double price, String author, Integer reserve) {this.id = id;this.name = name;this.price = price;this.author = author;this.reserve = reserve;}public Integer getId() {return id;}public void setId(Integer id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Double getPrice() {return price;}public void setPrice(Double price) {this.price = price;}public String getAuthor() {return author;}public void setAuthor(String author) {this.author = author;}public Integer getReserve() {return reserve;}public void setReserve(Integer reserve) {this.reserve = reserve;}@Overridepublic String toString() {return "Book{" +"id=" + id +", name='" + name + '\'' +", price=" + price +", author='" + author + '\'' +", reserve=" + reserve +'}';}
}

（3）创建BookDao类，完成增加图书信息的方法，并编写Test测试类测试。

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;public class BookDao {static Connection con = null;static ResultSet set=null;static PreparedStatement ps=null;public static void addBook(String name,double price,String author,int reserve) {String sql="insert into book values(null,?,?,?,?);";try {con=JDBCUtil.getCon();ps=con.prepareStatement(sql);ps.setString(1,name);ps.setDouble(2,price);ps.setString(3,author);ps.setInt(4,reserve);ps.executeUpdate();} catch (SQLException e) {e.printStackTrace();}finally {JDBCUtil.closeAll(null,ps,con);}}public static void select(){String sql="select *from book";con=JDBCUtil.getCon();try {ps=con.prepareStatement(sql);set= ps.executeQuery();while (set.next()){System.out.println("Book{" +"id=" + set.getInt("id") +", name='" + set.getString("name") + '\'' +", price=" + set.getDouble("price") +", author='" + set.getString("author") + '\'' +", reserve=" + set.getInt("reserve") +'}');}} catch (SQLException e) {e.printStackTrace();}finally {JDBCUtil.closeAll(set,ps,con);}}
}

Test

public class Test {public static void main(String[] args) {BookDao.addBook("老人与海",32.1,"海明威",4);BookDao.select();}
}

2、使用循环和break、continue等流程控制语句，计算1-n全部偶数的和，n的值在控制台输入。

import java.util.Scanner;/*** @author whlie(true){learn}*/
public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n = scanner.nextInt();int sum = 0;for (int index = 1; index < n; index++) {if (index % 2 != 0) {continue;}sum += index;}System.out.println(sum);}
}

3、一张纸的厚度大约是0.08mm，对折多少次之后能达到或超过珠穆朗玛峰的高度（8848.13米）。

public class Main {public static void main(String[] args) {//为了便于计算将原值扩大100倍long start=8;//1mm=0.001mlong end=884813000;long count=0;while (start<end){start*=2;count++;}System.out.println(count);}
}

4、创建一个存储13张牌面值的集合，如“A,1,2...Q,K”,采用高级for循环或者迭代器方法遍历集合数据输出。

import java.util.*;/*** @author whlie(true){learn}*/
public class Main {public static void main(String[] args) {String[] card=new String[]{"2","3","4","5","6","7","8","9","10","J","Q","K","A"};List<String> list = Arrays.asList(card);//高级for循环for(String s:list){System.out.print(s+" ");}//迭代器Iterator<String> iterator = list.iterator();while (iterator.hasNext()){System.out.print(iterator.next()+" ");}}
}

5、计算控制台输入的任意字符串中每个字符出现的次数。如abbbcccdabc，输出如：

a出现次数为:2

b出现次数为:4

c出现次数为:4

d出现次数为:1

这道题的题意不明，控制台输入字符串的范围没给，从样例推测字符串只包含小写字符。

import java.util.*;/*** @author whlie(true){learn}*/
public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);String s= scanner.nextLine();char[] chars = s.toCharArray();int[] array=new int[26];for(char c:chars){array[c-'a']++;}for (int i = 0; i < array.length; i++) {if (array[i]>0){System.out.println((char)(i+'a')+"出现次数为:"+array[i]);}}}
}

6、一辆卡车违反交通规则，撞人后逃跑。现场有三人目击事件，但都没有记住车号，只记下车号的一些特征。

甲说：牌照的前两位数字是相同的；

乙说：牌照的后两位数字是相同的，但与前两位不同；

丙是数学家，他说：四位的车号刚好是一个整数的平方。请根据以上线索求出车号。

public class Main {public static void main(String[] args) {for (int i = 1000; i < 10000; i++) {if (judgeSame(i)&&judgeSqrt(i)){System.out.println(i);}}}/*** 判断甲和乙的条件* 1.前两位相同* 2.后两位相同* 3.前两位和后两位不能相同*/public static boolean judgeSame(int i){char[] chars = (i + "").toCharArray();return chars[0]==chars[1]&&chars[2]==chars[3]&&chars[0]!=chars[3];}/*** 判断丙的条件* 1.是否为完全平方数*/public static boolean judgeSqrt(int i){double a=Math.sqrt(i);return a==(int)a;}
}

7、马克思手稿中有一道趣味数学问题：有30个人，其中有男人、女人和小孩，在一家饭馆吃饭花了50先令；每个男人花3先令，每个女人花2先令，每个小孩花1先令；问男人、女人和小孩各有几人？

public class Main {public static void main(String[] args) {int count=1;for (int i = 1; i < 16; i++) {for (int j = 1; j < 25; j++) {for (int k = 1; k < 50; k++) {if (i+j+k==30&&3*i+2*j+1*k==50){System.out.println("第"+(count++)+"种可能:");System.out.print("男人:"+i+"个 " +"女人:"+j+"个 " +"小孩:"+k+"个\n");}}}}}
}

8、中国有句俗语叫“三天打鱼两天晒网”。某人从1990年1月1日起开始“三天打鱼两天晒网”，问这个人在以后的某一天中是“打鱼”还是“晒网”？

个人理解:三天打鱼两天晒网是指先连续打三天鱼再连续晒两天网，5天一次循环

1,2,3天打鱼，4,5天晒网，第0天相当于上次循环的第5天

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.*;/*** @author whlie(true){learn}*/
public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.print("请依次输入年月日,以空格间隔:");int year=scanner.nextInt();int month=scanner.nextInt();int day = scanner.nextInt();long between = ChronoUnit.DAYS.between(LocalDate.of(1990, 1, 1),LocalDate.of(year, month, day));long result=(between+1)%5;System.out.println(result<4?result==0?"晒网":"打鱼":"晒网");}
}

9、创建一个名为Shape的接口，接口内有一个计算面积的抽象方法。定义一个Circle类，实现Shape接口，并实现接口里的抽象方法。

public interface Shape {public double area(double r);
}

public class Circle implements Shape{@Overridepublic double area(double r) {return r*r*Math.PI;}
}

10、创建如图所示的窗口。

import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;public class TextMain {public static String Signin;public static String register;JFrame jFrame;public static void main(String[] args) {init();}public static void init(){JFrame jFrame=new JFrame("hello");jFrame.setBounds(200, 200, 500, 400);jFrame.setLayout(null);JLabel jLabel1=new JLabel();jLabel1.setBounds(130, 100, 100, 100);jLabel1.setText("姓名:");jFrame.add(jLabel1);JLabel jLabel2=new JLabel();jLabel2.setBounds(130, 150, 100, 100);jLabel2.setText("密码:");jFrame.add(jLabel2);final JTextField jTextField=new JTextField();jTextField.setBounds(165, 135, 200, 30);jFrame.add(jTextField);final JTextField jTextField1=new JTextField();jTextField1.setBounds(165, 185, 200, 30);		jFrame.add(jTextField1);JButton jButton=new JButton();jButton.setBounds(130, 250, 85, 50);jButton.setText("登录");jFrame.add(jButton);JButton jButton1=new JButton();jButton1.setBounds(280, 250, 85, 50);jButton1.setText("注册");jFrame.add(jButton1);jFrame.setVisible(true);}
}

11、给上述窗口的登录按钮绑定点击事件，点击后获取用户在文本框输入的姓名和密码，打印输出到控制台上。(在10的基础上增加键盘监听事件)

    jTextField.addKeyListener(new KeyListener() {@Overridepublic void keyTyped(KeyEvent e) {// TODO 自动生成的方法存根if(e.getKeyChar()==KeyEvent.VK_ENTER&&!jTextField.getText().equals("")){Signin=jTextField.getText();System.out.println("姓名为:"+Signin);}}@Overridepublic void keyReleased(KeyEvent e) {}@Overridepublic void keyPressed(KeyEvent e) {}});jTextField1.addKeyListener(new KeyListener() {@Overridepublic void keyTyped(KeyEvent e) {if(e.getKeyChar()==KeyEvent.VK_ENTER&&!jTextField1.getText().equals("")){register=jTextField1.getText();System.out.println("密码为:"+register);}}@Overridepublic void keyReleased(KeyEvent e) {}@Overridepublic void keyPressed(KeyEvent e) {}});jButton.addActionListener(new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {Signin=jTextField.getText();System.out.println("姓名为:"+Signin);register=jTextField1.getText();System.out.println("密码为:"+register);}});

12、使用Canvas类，绘制红色字符串“hello”，显示在JFrame窗口中。

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import javax.swing.JFrame;public class TextMain {public static String Signin;public static String register;JFrame jFrame;public static void main(String[] args) {JFrame jFrame1=new JFrame("Canvas");jFrame1.setBounds(200, 200, 500, 400);jFrame1.setLayout(null);Can can=new Can();can.setBounds(20, 20, 400, 400);jFrame1.add(can);jFrame1.setVisible(true);}
}
class Can extends Canvas{@Overridepublic void paint(Graphics g) {super.paint(g);g.setFont(new Font("黑体", Font.BOLD, 50));g.setColor(new Color(255,0,0));g.drawString("hello", 100, 100);}
}