Java语言程序设计案例教程 -习题及答案

PAGEPAGE1《Java语言程序设计案例教程》习题参考答案习题一一、选择题1、 C 2、B 3、B 4、A 5、D 6、C二、简答题1、Java语言的特点：Java2、（1）新建Java工程File->New->JavaProject（2）新建包 New->Package（3）新建类 New->Class（4）编写源文件（5）运行源文件3、publicclass test{publicstaticvoidmain(String[]args){System.out.println("这是****Java程序。");}}习题二一、选择题1、D 2、A3、D 4、B 5、D 6、B 7、D 8、C 9、D 10、B 、B二、编程题1、publicstaticvoidmain(String[]args){Scannersc=newScanner(System.in);intnum=sc.nextInt();if(num%2==0){System.out.println(num+"是偶数");}else}}

System.out.println(num+"是奇数");2、publicstaticvoidmain(String[]args){System.out.println("请输入全年应纳税所得额");Scannersc=newScanner(System.in);doubletaxableIncome=sc.nextDouble();doubletax=0;if(taxableIncome<=36000){tax=taxableIncome*0.03;}elseif(taxableIncome<=144000){tax=taxableIncome*0.1-2520;}elseif(taxableIncome<=300000){tax=taxableIncome*0.2-16920;}elseif(taxableIncome<=420000){tax=taxableIncome*0.25-31920;}elseif(taxableIncome<=660000){tax=taxableIncome*0.3-52920;}elseif(taxableIncome<=960000){tax=taxableIncome*0.35-85920;}else{tax=taxableIncome*0.45-181920;}System.out.println("应缴纳个人所得税税额为："+tax);}3、publicstaticvoidmain(String[]args){for(inti=100;i<=999;i++){intbai=i/100;intshi=i/10%10;intge=i%10;if(bai*bai*bai+shi*shi*shi+ge*ge*ge==i){System.out.println(i);}}}4、publicstaticvoidmain(String[]args){inti,j;for(i=1;i<10;i++){for(j=1;j<=i;j++){System.out.print(i+"x"+j+"="+i*j+""); }System.out.println();}}5、publicstaticvoidmain(String[]args){Scannerscan=newScanner(System.in);intn=scan.nextInt();Doublesum=0.0;//及格人数Doublesum2=0.0;//优秀人数for(inti=0;i<n;i++){inta=scan.nextInt();if(a>=60){sum++;}//及格人数if(a>=85){sum2++;}//优秀人数}System.out.print(Math.round(sum*100/n)+"%");System.out.print(Math.round(sum2*100/n)+"%");scan.close();}6、publicstaticvoidmain(String[]args){//方法一intcount=0;for(inti=1;i<=2020;i++){Strings=String.valueOf(i);if(s.contains("2")){//s2for(intj=0;j<s.length();j++){if(s.charAt(j)=='2'){count++;}}}}System.out.println(count);//方法二intcount=0;for(inti=1;i<=2020;++i){intt=i;while(t>0){if(t%10==2){count++;}t/=10;}}System.out.println(count);}习题三一、选择题1、B 2、A3、A4、C 5、C 6、B 7、D 8、C9、D10、A、B12、B 13、A二、编程题1、publicclassRectangle{intlength;intwidth;publicRectangle(intlength,intwidth){this.length=length; this.width=width;}publicvoidgetcir(){intcir=2*(this.length+this.width);System.out.println("长方形的周长为："+cir);}publicvoidgetArea(){intarea=this.length*this.width;System.out.println("长方形的面积为："+area);}publicstaticvoidmain(String[]args){Rectangler=newRectangle(3,5);r.getArea(); r.getcir();}}2、publicclassFruit{Stringname;intnum;floatprice;publicFruit(Stringname,intnum,floatprice){=name;this.num=num;this.price=price;}publicstaticvoidmain(String[]args){Fruitapple=newFruit("apple",50,5.0f);Fruitpear=newFruit("pear",20,3.5f);FruitBanana=newFruit("banana",10,2.5f);System.out.println("苹果的数量为："+apple.num+";单价为："+apple.price+"元");System.out.println("梨的数量为："+pear.num+";单价为："+pear.price+"元");System.out.println("香蕉的数量为："+Banana.num+";单价为："+Banana.price+"元");}}3、//学生类，封装学生的学号、姓名、成绩等信息。publicclassStu{StringstuID;StringstuName;floatscore;publicStu(Stringname,Stringid,floatscore){this.stuID=id;this.stuName=name;this.score=score;}}//主类publicclassmainTest{//打印输出学生信息publicvoidprintout(Stus){System.out.println("学号为："+s.stuID+";姓名为："+s.stuName+";成绩为："+s.score);}publicstaticvoidmain(String[]args){Stus=newStu("张三","001",90.0f);mainTestt=newmainTest();t.printout(s);}}4、//Employee父类publicclassEmployee{Stringname;floatbasic;Stringaddress;publicEmployee(Stringname,floatbasic,Stringaddress){=name;this.basic=basic;this.address=address;}publicvoidshow(){System.out.println("姓名为："++"；基本工资为："+this.basic+"；地址为："+this.address);}}//Manager子类publicclassManagerextendsEmployee{Stringdepartment;publicManager(Stringname,floatbasic,Stringaddress,Stringdepartment){super(name,basic,address);this.department=department;}publicvoidshow(){System.out.println("姓名为："++"；基本工资为："+this.basic+"；地址为："+this.address+"；部门为："+this.department);}publicstaticvoidmain(String[]args){Employeea=newManager("张三",2000.0f,"江苏","研发");a.show();}}//Director子类publicclassDirectorextendsEmployee{Stringtransport;publicDirector(Stringname,floatbasic,Stringaddress,Stringtransport){super(name,basic,address);this.transport=transport;}publicvoidshow(){System.out.println("姓名为："++"；基本工资为："+this.basic+"；地址为："+this.address+"；交通工具为："+this.transport);}publicstaticvoidmain(String[]args){Employeea=newDirector("李四",5000.0f,"江苏","公交");a.show();}}5、//父类AdditionclassAddition{publicAddition(){}publicvoidadd(){System.out.println("父类Addition中的add()方法"); }}//NumberAddition类classNumberAdditionextendsAddition{publicvoidadd(){inta=5;intb=10;intc=a+b;System.out.println("NumberAddition类Addition中的add()方法:"+c);}}//TextConcatenation类classTextConcatenationextendsAddition{publicvoidadd(){Stringa="hello";Stringb="world";Stringc=a+b;System.out.println("TextConcatenation类Addition中的add()方法:"+c);}}//主类publicclassmainTest{publicstaticvoidmain(String[]args){NumberAdditionn=newNumberAddition();TextConcatenationt=newTextConcatenation();n.add();t.add();}}6、interfaceShape{voidgetArea();voidgetCir();}classRectangleimplementsShape{floatlength;floatwidth;publicRectangle(floatlength,floatwidth){this.length=length;this.width=width;}publicvoidgetArea(){System.out.println("矩形的面积为："+this.length*this.width);}publicvoidgetCir(){ System.out.println("矩形的周长为："+2*(this.length+this.width));}}publicclasst1{publicstaticvoidmain(String[]args){Rectangler=newRectangle(2.0f,1.5f);r.getArea();r.getCir();}}习题四一、选择题1、C 2、B 3、C 4、D 5、B 6、D 7、C 8、A9、D 10、D二、编程题1、publicclassmainTest{//排序publicArrayList<String>Sort(ArrayList<String>a){inty=a.size();Stringstr1="";Stringstr2="";intflag;for(intx=0;x<a.size()-1;x++){for(inti=0;i<y-1;i++){str1=a.get(i);str2=a.get(i+1);flag=pareToIgnoreCase(str2);if(flag>=0){a.set(i,str2);a.set(i+1,str1);}}y=y-1;}returna;}publicstaticvoidmain(String[]args){ArrayList<String>a=newArrayList<String>(5);a.add("grape");a.add("orange");a.add("banana");a.add("apple");a.add("peach");mainTestt=newmainTest();ArrayList<String>b=t.Sort(a);for(intj=0;j<b.size();j++){System.out.println(b.get(j));}}}2.publicstaticvoidmain(String[]args){System.out.println("请输入名字:");Scannersca=newScanner(System.in);Strings=sca.next();System.out.println("姓是:"+s.substring(0,1)+"；名为"+s.substring(1));}3、importjava.util.ArrayList;//Cat类classCat{Stringname;publicCat(Stringname){=name;}publicvoidshow(){PAGEPAGE10System.out.println("name的值为："+);}}//CatTest类publicclassCatTest{publicstaticvoidmain(String[]args){ArrayList<Cat>a=newArrayList<Cat>();a.add(newCat("cat1"));a.add(newCat("cat2"));a.add(newCat("cat3"));for(inti=0;i<a.size();i++){Catr=a.get(i);r.show();}}}4、importjava.util.HashMap;classBook{Stringtitle;publicBook(Stringtitle){this.title=title;}publicStringtoString(){returntitle;}}publicclassBookTest{publicstaticvoidmain(String[]args){HashMaphm=newHashMap();hm.put("001",newBook("Java程序设计"));hm.put("002",newBook("JSP应用开发"));Bookb=(Book)hm.get("001");System.out.println("标题为："+b.toString());}}5、importjava.util.HashMap;importjava.util.Iterator;importjava.util.Set;publicclassStuTest{publicstaticvoidmain(String[]args){//创建HashMap对象hm，用put方法赋值HashMap<String,Integer>hm=newHashMap<String,Integer>();hm.put("张三",newInteger(98));hm.put("李四",newInteger(78));//打印学生成绩Set<String>key=hm.keySet();Iterator<String>it=key.iterator();System.out.print("成绩依次为：");while(it.hasNext()){System.out.print(hm.get(it.next())+" ");}//修改张三的成绩hm.put("张三",newInteger(88));//打印学生成绩key=hm.keySet();it=key.iterator();System.out.print("\n修改后的成绩依次为：");while(it.hasNext()){System.out.print(hm.get(it.next())+" ");}}}6.importjava.util.Scanner;publicclassMain{publicstaticvoidmain(String[]args){Scannersc=newScanner(System.in);Strings=sc.nextLine();intmax=0;intindex=0;Stringa="abcdefghijklmnopqrstuvwxyz";intb[]=newint[26];for(inti=0;i<s.length();i++){b[a.indexOf(s.charAt(i))]++;}for(intj=0;j<b.length;j++){if(b[j]>max){max=b[j];index=j;}}System.out.println(a.substring(index,index+1));System.out.println(max);}}习题五一、选择题1、C 2、C 3、B 4、A5、C 6、C二、编程题1、publicclassOutOfBound{publicstaticvoidmain(String[]args){int[]array={3,6,7,5,8,1,2,4,9,10};inti=0;try{System.out.println("元素的值为："+array[i]);}catch(ArrayIndexOutOfBoundsExceptione){System.out.println("数组下标越界了！");}}}2、classMyExceptionextendsException{privateStringcontent;//构造方法publicMyException(Stringcontent){this.content=content;}//获取异常描述信息publicStringgetContent(returncontent;}}publicclassTest{//检查字符串元素是否都为小写字母publicstaticvoidcheck(inti)throwsMyException{if(i<0)//MyException异常类对象thrownewMyException(i+"为负数，不能做为数组长度！");}publicstaticvoidmain(Stringargs[]){//键盘输入一个整数System.out.println("请输入一个整数:");Scannerscan=newScanner(System.in);intlen=scan.nextInt();len=len-20;try{//检测数组长度的值check(len);}catch(MyExceptione){//处理异常System.out.println(e.getContent());}}}习题六一、选择题1、A2、D 3、C 4、D 5、C二、编程题1、//取消按钮事件privatevoidjButton2ActionPerformed(java.awt.event.ActionEventevt){System.exit(0);}//确定按钮事件privatevoidjButton1ActionPerformed(java.awt.event.ActionEventevt){Stringname=jTextField1.getText();Stringpass=newString(jPasswordField1.getPassword());if(name.trim().equals("abc")&&pass.trim().equals("abc")){jLabel3.setText("验证通过！");}elsejLabel3.setText("非法的用户名或密码！");}2、//斜体privatevoidjMenuItem4ActionPerformed(java.awt.event.ActionEventevt){jTextArea1.setFont(newFont(null,Font.ITALIC,12));}//蓝色privatevoidjMenuItem3ActionPerformed(java.awt.event.ActionEventevt){jTextArea1.setForeground(Color.blue);}//绿色privatevoidjMenuItem2ActionPerformed(java.awt.event.ActionEventevt){jTextArea1.setForeground(Color.green);}//红色privatevoidjMenuItem1ActionPerformed(java.awt.event.ActionEventevt){jTextArea1.setForeground(Color.red);}//退出privatevoidjMenuItem5ActionPerformed(java.awt.event.ActionEventevt){System.exit(-1);}习题七一、选择题1、A 2、B 3、C 4、A 5、A二、编程题Statementcustomer的访问并输出。importjava.sql.Connection;importjava.sql.DriverManager;importjava.sql.ResultSet;importjava.sql.SQLException;importjava.sql.Statement;publicclassex1{publicstaticvoidmain(String[]args){try{//加载驱动Class.forName("com.mysql.jdbc.Driver");//建立连接Connectioncon=DriverManager.getConnection("jdbc:mysql://localhost:3306/dbstudent?characterEncoding=utf-8","root","123456");//实例化Statement对象Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);//执行SQL语句Stringsql="select*fromcustomer";ResultSetrs=stmt.executeQuery(sql);//处理结果集while(rs.next()){System.out.println("读者编号："+rs.getInt("id")+"\t姓名："+rs.getString("name")+"\t地址："+rs.getString("address"));}//关闭连接if(rs !=null)rs.close();if(stmt!=null)stmt.close();if(conn!=null)conn.close();}catch(SQLExceptionex){System.out.println(ex.getMessage()+"路径错误");}catch(ClassNotFoundExceptionex){System.out.println(ex.getMessage()+"驱动错误");}}}PreparedStatementCustomerIDimportjava.sql.Connection;importjava.sql.DriverManager;importjava.sql.PreparedStatement;importjava.sql.SQLException;publicclassex1{publicstaticvoidmain(String[]args){//定义sql语句Stringsql="deletefromcustomerwhereid=?";try{//加载驱动Class.forName("com.mysql.jdbc.Driver");//建立连接Connectioncon=DriverManager.getConnection("jdbc:mysql://localhost:3306/dbstudent?characterEncoding=utf-8","root","123456");//实例化PreparedStatement对象PreparedStatement ps=conn.prepareStatement(sql);//给参数赋值ps.setInt(1,1);//执行SQL语句inti=ps.executeUpdate();//操作判断if(i==1){System.out.println("记录删除成功！");}elseSystem.out.println("记录删除失败！");//关闭连接if(ps!=null)ps.close();if(conn!=null)conn.close();}catch(SQLExceptionex){ System.out.println(ex.getMessage路径错误");}catch(ClassNotFoundExceptionex){ System.out.println(ex.getMessage驱动错误");}}}PreparedStatementCustomerID的记录，并在控制台输出操作是否成功。importjava.sql.Connection;importjava.sql.DriverManager;importjava.sql.PreparedStatement;importjava.sql.SQLException;publicclassex1{publicstaticvoidmain(String[]args){//定义sql语句Stringsql="updatecustomersetname=?whereid=?";try{//加载驱动Class.forName("com.mysql.jdbc.Driver");//建立连接Connectioncon=DriverManager.getConnection("jdbc:mysql://localhost:3306/dbstudent?characterEncoding=utf-8","root","123456");//实例化PreparedStatement对象PreparedStatement ps=conn.prepareStatement(sql);//给参数赋值ps.setString(1,"kitty");ps.setInt(2,2);//执行SQL语句inti=ps.executeUpdate();//操作判断if(i==1){System.out.println("记录更新成功！");}elseSystem.out.println("记录更新失败！");//关闭连接if(ps!=null)ps.close();if(conn!=null)conn.close();}catch(SQLExceptionex){ System.out.println(ex.getMessage路径错误");}catch(ClassNotFoundExceptionex){ System.out.println(ex.getMessage驱动错误");}}}习题八一、选择题1、B 2、D 3、A 4、C 5、C 6、D二、编程题1、JavaThreadRunnable接口。Threadrun()run()方法中编写线程执行的代newstart方法启动线程。RunnableRunnablerun()方法，run()方法中编写线程执行的代码,Thread构造方法，以实现类的实例对象为参数创ThreadThreadstart()方法启动线程。2、importjavax.swing.JFrame;importjavax.swing.JLabel;importjava.awt.BorderLayout;importjava.text.SimpleDateFormat;importjava.util.Date;publicclassTimeextendsJFrameimplementsRunnable{privateJLabeltimeLabel=null;privateDated=null;publicstaticvoidmain(Stringargs[]){newTime();}publicTime(){this.setTitle("多线程");this.setSize(400,300);this.setVisible(true);this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);timeLabel=newJLabel();this.getContentPane().add(timeLabel,BorderLayout.NORTH);Threadt=newThread(this);t.start();}publicvoidrun(){while(true){d=newDate();SimpleDateFormatformat=new SimpleDateFormat("yyyy-MM-ddHH:mm:ss");Stringtime=format.format(d);timeLabel.setText("现在的时间是："+time);}}}习题九一、选择题1、D 2、A3、B 4、C 5、A6、B二、编程题1、importjava.io.BufferedReader;importjava.io.BufferedWriter;importjava.io.FileReader;importjava.io.FileWriter;importjava.io.IOException;publicclassTest{publicstaticvoidmain(Stringargs[]){BufferedReaderbr=null;BufferedWriterbw=null;try{

//根据字符流对象建立缓冲流对象bw=newBufferedWriter(newFileWriter("src/result.txt"));br=newBufferedReader(newFileReader("src/Stu.txt"));Stringstr=null;//初始化行号inti=1;//读取数据while((str=br.readLine())!=null){bw.write(i+"");//写入行号bw.write(str);bw.newLine();//写入换行符i++;}bw.flush();//刷新缓冲输入流}catch(IOExceptione){e.printStackTrace();}finally{try{//关闭缓冲流PAGEPAGE20bw.close();br.close();}catch(IOExceptione){e.printStackTrace();}}}}2、importjava.io.File;importjava.io.FileInputStream;importjava.io.FileOutputStream;importjava.io.IOException;publicclassTest{publicstaticvoidmain(Stringargs[]){try{Filef_in=newFile("src/fin.txt");//创建字节流对象FileOutputStreamfos=newFileOutputStream("src/fout.txt");FileInputStreamfis=newFileInputStream(f_in);for(inti=0;i<80;i++){fos.write(fis.read());}System.out.println("文件读写完成!");fos.close();fis.close();}catch(IOExceptione){System.out.println("文件读写异常!");}}}3、importjava.io.File;importjava.io.FileReader;importjava.io.FileWriter;importjava.io.IOException;publicclassTest{publicstaticvoidmain(Stringargs[]){try{Filef_in=newFile("src/fin.txt");//创建字节流对象FileWriterfw=newFileWriter("src/fout.txt");FileReaderfr=newFileReader(f_in);intstr;//初始化计数inti=0;//读写数据while((str=fr.read())!=-1){fw.write(str);i++;//换行if(i%40==0){fw.write("\n");}}fw.flush();//刷新缓冲输入流System.out.println("文件读写完成!");fw.close();fr.close();}catch(IOExceptione){System.out.println("文件读写异常!");}}}习题十一、选择题1、C 2、B 3、C 4、D 5、A 6、C二、编程题1、publicstaticvoidmain(String[]args){try{//根据域名得到IPInetAddressadd