《Java面向对象程序设计》(第2版)课后答案

Java面向对象程序设计（编著耿祥义X跃平）习题11．JamesGosling2．使用一个文本编辑器编写源文件。Java编译器Java源程序，得到字节码文件。Java解释器Java程序3．Java的源文件是由若干个书写形式互相独立的类组成的。应用程序中可以没有public类，若有的话至多可以有一个public类。4．系统环境path D\jdk\bin;系统环境classpath D\jdk\jre\lib\rt.jar;.;BJava。Java.class。D8）生成两个字节码文件，这些字节码文件的名字Speak.classXiti8.classjavaXiti8javaSpeak的错误提示Exceptioninthread"main"java.lang.NoSuchMethodError:main执行javaxiti8得到的错误提示Exceptioninthread"main"java.lang.NoClassDefFoundError:xiti8(wrongname:Xiti8)执行javaXiti8.class得到的错误提示Exceptioninthread"main"java.lang.NoClassDefFoundError:Xiti8/classjavaXiti8I'mgladtomeetyou9．属于操作题，解答略。习题2D【代码1【代码2】错误 //【代码3】更正为floatz=6.89F;t对于eXiti4{publicstaticvoidmain(Stringargs[]){charch1='你',ch2='我',ch3='他';System.out.println("\""+ch1+"\"的位置:"+(int)ch1);System.out.println("\""+ch2+"\"的位置:"+(int)ch2);System.out.println("\""+ch3+"\"的位置:"+(int)ch3);}}5.length6.length7】【代码2】-127【代码3】 123456.783,123456.783128．【代码1】false【代码2】true【代码3】false【代码4】35】4.46】8.8习题3输出110if-else语句书写的不够规X，复合语句缺少大括号“{}”，代码不够清晰。2．你好好酷!!3．publicclassXiti3_3{publicstaticvoidmain(Stringargs[]){intstartPosition=0,endPosition=0;charcStart='а',cEnd='я';startPosition=(int)cStart;//cStart做int型转换据运算并将结果赋值给startPositionendPosition=(int)cEnd; //cEnd做int型转换运算，并将结果赋值给endPositionSystem.out.println("俄文字母表：");for(inti=startPosition;i<=endPosition;i++){charc='\0';c=(char)i; //ichar型转换运算，并将结果赋值给cSystem.out.print("+c);if((i-startPosition+1)%10==0)System.out.println("");}}}4．publicclassXiti4{ publicstaticvoidmain(Stringargs[]){ doublesum=0,a=1;inti=1;while(i<=20){sum=sum+a;i++;a=a*i;}System.out.println("sum="+sum);}}5．classXiti5{ publicstaticvoidmain(Stringargs[]){inti,j;{for(i=2;i<=j/2;i++){if(j%i==0)break;}if(i>j/2)(""+j);}}}}6．classXiti6{ publicstaticvoidmain(Stringargs[]){ doublesum=0,a=1,i=1;while(i<=20){sum=sum+a;i++;a=(1.0/i)*a;}System.out.println("使用while循环计算的sum="+sum);for(sum=0,i=1,a=1;i<=20;i++){ sum=sum+a;}System.out.println("使用for循环计算的sum="+sum);}}7．publicclassXiti7{ publicstaticvoidmain(Stringargs[]){ intsum=0,i,j;{ for(j=1,sum=0;j<i;j++){ if(i%j==0)sum=sum+j;if(sum==i)}

}System.out.println("完数:"+i);}}8．方法之一importjava.util.Scanner;publicclassXiti8{ publicstaticvoidmain(Stringargs[]){System.out.println("请输入两个非零正整数，每输入一个数回车确认");Scannerreader=newScanner(System.in);intm=0,n=0,temp=0,gy=0,gb=0,a,b;a=m=reader.nextInt();b=n=reader.nextInt();if(m<n){ }intr=m%n;while(r!=0){ n=m;}

m=n;n=temp;m=r;r=m%n;gy=n;gb=a*b/gy;}

System.out.println("最大公约数："+gy);System.out.println("最小公倍数："+gb);}8．方法之二importjava.util.Scanner;publicclassXiti8{publicstaticvoidmain(Stringargs[]){System.out.println("请输入两个非零正整数，每输入一个数回车确认");Scannerreader=newScanner(System.in);intm=0,n=0,t=0,gy=0,gb=0;m=reader.nextInt();n=reader.nextInt();if(m>n){}

t=m;m=n;n=t;for(inti=1;i<=m;i++){if(m%i==0&&n%i==0){gy=i;}}gb=m*n/gy;System.out.println(m+","+n+"的最大公约数为"+gy);System.out.println(m+","+n+"的最小公倍数为"+gb);}}9．publicclassXiti9{ publicstaticvoidmain(Stringargs[]){intn=1;longsum=0,t=1;t=n*t;while(true){ sum=sum+t;if(sum>9999)break;n++;t=n*t;}System.out.println("满足条件的最大整数:"+(n-1));}}//1至7的阶乘和是sum=5913.0 //1至8的阶乘和是sum=46233.0习题412同，即或者是参数的个数不同，或者是参数的类型不同。构造方法可以重载。3．可以。不可以。不可以。static修饰的变量是类变量。那么类变量和实例new运算符可以创建多个不同的对象，不同的对象的量。也就是说对象共享类变量。C，D148．sum=-1009．2710.**20##1005private的成员变量privatepublic成员变量做为子类的成员变量，并且继承了父类的public里，子类不能继承父类的友好变量和友好方法。只要子类中声明的成员变量和父类中的成员变量同名时，子类就隐藏了继承的成员变量。义的方法称作子类重写的方法。子类通过方法的重写可以隐藏继承的方法。不可以。3．abstract4．假设B类是A类子类或间接子类，当我们用子类B创建一个对象，并把这个对象的引用放到A类的对象中时，称这个A类对象是子类对象的上转型对象。5．可以把实现某一接口的类创建的对象的引用赋给该接口声明的接口变量中。那么该接口变量就可以调用被类实现的接口中的方法。6．A，C，D7．15.08.08．98.0129．classA{ publicfinalvoidf(){charcStart='a',cEnd='z';for(charc=cStart;c<=cEnd;c++)(""+c);}}}classBextendsA{publicvoidg(){charcStart='α',cEnd='ω';for(charc=cStart;c<=cEnd;c++)(""+c);}}}publicclassXiti9{ publicstaticvoidmain(Stringargs[]){Bb=newB();b.f();b.g();}}10．classA{ publicintf(inta,intb){if(b<a){ inttemp=a;}intr=b%a;while(r!=0){ b=a;}

a=b;b=temp;a=r;r=b%a;returna;}}classBextendsA{ publicintf(inta,intb){ intdivision=super.f(a,b);return(a*b)/division;}}publicclassXiti10{ publicstaticvoidmain(Stringargs[]){Aa=newA();Bb=newB();System.out.println("最大公约数："+a.f(36,24));System.out.println("最小公倍数："+b.f(36,24));}}习题61可以。不可以。大家好，祝工作顺利！5．96乘数超过99习题71．Strategy是接口。Army不是抽象类。ArmyStrategy是关联关系。StrategyA,、StrategyCStrategy是实现关系。2．3．13闭原则。17闭原则。习题8采用新增的策略为选手计算得分。StrategyFourdoublecomputeScore(double[]方法实现为去掉数组a的元素中的一个最大值和一个最小值，然后计算剩余元素的几何平均值。importjava.util.Arrays;publicclassStrategyFourimplementsComputableStrategy{publicdoublecomputeScore(double[]a){if(a.length<=2)return0;doublescore=0,multi=1;Arrays.sort(a);intn=a.length-2;for(inti=1;i<a.length-1;i++){multi=multi*a[i];}score=Math.pow(multi,1.0/n);returnscore;}}2．publicinterfacePrintCharacter{publicabstractvoidprintTable(char[]a,char[]b);}具体策略PrintStrategyOne.javapublicclassPrintStrategyOneimplementsPrintCharacter{publicvoidprintTable(char[]a,char[]b){for(inti=0;i<a.length;i++)System.out.print(a[i]+",");}for(inti=0;i<b.length;i++)System.out.print(b[i]+",");}System.out.println("");}}PrintStrategyTwo.javapublicclassPrintStrategyTwo{publicvoidprintTable(char[]a,char[]b){for(inti=0;i<a.length;i++){System.out.print(b[i]+","+a[i]+",");}}}（3）PrintGame.javapublicclasPrintGame{PrintCharacterstrategy;publicvoidsetStrategy(PrintCharacterstrategy){this.strategy=strategy;}publicvoidgetPersonScore(char[]a,char[]b){if(strategy==null)System.out.println("sorry!");elsestrategy.printTable(a,b);}}应用以上策略:publicclassApplication{publicstaticvoidmain(Stringargs[]){char[]a=newchar[26];char[]b=newchar[26];for(inti=0;i<=25;i++){a[i]=(char)('a'+i);}for(inti=0;i<=25;i++){b[i]=(char)('A'+i);}PrintGamegame=newPrintGame();//上下文对象game.setStrategy(newPrintStrategyOne()); //上下文对象使用策略一System.out.println("方案1:");game.getPersonScore(a,b);game.setStrategy(newPrintStrategyTwo()); //2:");game.getPersonScore(a,b);}}3．参照本章自主完成。习题91．A，B，DLove:Game3．13abc夏日4．135795．9javaHello6．publicclassXiti6{publicstaticvoidmain(Stringargs[]){Strings1,s2,s3,t1="ABCDabcd";System.out.println(""+t1);s1=t1.toUpperCase();System.out.println(""+s1);s2=t1.toLowerCase();System.out.println("字符串中的大写字母变成小写是这个样子:"+s2);s3=s1.concat(s2);System.out.println("大写字符串连接小写字符串是这个样子:"+s3);}}7．classXiti7{publicstaticvoidmain(Stringargs[])String s="XX国chara=s.charAt(0);charb=s.charAt(6);System.out.println("第一个字: "+a);"+b);}}8．importjava.util.*;classXiti8{ publicstaticvoidmain(Stringargs[]){intyear,month;System.out.println("请输入年份和月份，每输入一个数回车确认");Scannerreader=newScanner(System.in);year=reader.nextInt();month=reader.nextInt();String[]day=newString[42];System.out.println("日一二三四五六");Calendarrili=Calendar.getInstance();rili.set(year,month-1,1);//将日历翻到year年month月1日,注意0表示一月...11表示十二月

int星期几=rili.get(Calendar.DAY_OF_WEEK)-1;intdayAmount=0;dayAmount=31;dayAmount=30;if(month==2)dayAmount=29;elsedayAmount=28;for(inti=0;i<星期几;i++)day[i]="";for(inti=星期几,n=1;i<星期几+dayAmount;i++){if(n<=9)day[i]=String.valueOf(n)+"";elseday[i]=String.valueOf(n);n++;}for(inti=星期几+dayAmount;i<42;i++)day[i]="";for(inti=0;i<星期几;i++){ day[i]="**";}for(inti=0;i<day.length;i++){if(i%7==0)("");}System.out.print(""+day[i]);}}}9．importjava.util.*;classXiti9{ publicstaticvoidmain(Stringargs[]){intyear1,month1,day1,year2,month2,day2;Scannerreader=newScanner(System.in);System.out.println("请输入第一个日期的年份月份日期，每输入一个数回车确认");year1=reader.nextInt();month1=reader.nextInt();day1=reader.nextInt();System.out.println("请输入第二个日期的年份月份日期，每输入一个数回车确认");year2=reader.nextInt();month2=reader.nextInt();day2=reader.nextInt();Calendarcalendar=Calendar.getInstance();calendar.set(year1,month1,day1);longtimeYear1=calendar.getTimeInMillis();calendar.set(year2,month2,day2);longtimeYear2=calendar.getTimeInMillis();long相隔天数=Math.abs((timeYear1-timeYear2)/(1000*60*60*24));System.out.println(""+year1+"年"+month1+"月"+day1+"日和"+year2+"年"+month2+"月"+day2+"日相隔"+相隔天数+"天");}}10．publicclassXiti10{ publicstaticvoidmain(Stringargs[]){ doublea=0,b=0,c=0;a=12;b=24;c=Math.max(a,b);System.out.println(c);c=Math.min(a,b);System.out.println(c);c=Math.pow(2,3);System.out.println(c);c=Math.abs(-0.123);System.out.println(c);c=Math.asin(0.56);System.out.println(c);c=Math.cos(3.14);System.out.println(c);c=Math.exp(1);System.out.println(c);c=Math.log(8);System.out.println(c);}}习题101．BorderLayout布局。2．不可以。A,C。4．importjava.util.StringTokenizer;importjava.awt.*;importjava.awt.event.*;importjavax.swing.*;publicclassXiti4{ publicstaticvoidmain(Stringargs[]){ComputerFramefr=newComputerFrame();fr.setTitle("计算的窗口");}}classComputerFrameextendsJFrameimplementsTextListener{ TextAreatext1,text2;intcount=1;doublesum=0,aver=0;publicComputerFrame(){setLayout(newFlowLayout());text1=newTextArea(6,20);text2=newTextArea(6,20);add(text1);add(text2);text2.setEditable(false);text1.addTextListener(this);setSize(300,320);setVisible(true);addWindowListener(newWindowAdapter(){ publicvoidwindowClosing(WindowEvente){ System.exit(0);validate();}

}});publicvoidtextValueChanged(TextEvente){ Strings=text1.getText();sum=0;aver=0;StringTokenizerfenxi=newStringTokenizer(s,",'\n'");intn=fenxi.countTokens();count=n;doublea[]=newdouble[n];for(inti=0;i<=n-1;i++){ Stringtemp=fenxi.nextToken();try{a[i]=Double.parseDouble(temp);sum=sum+a[i];}catch(Exceptionee){count--;}}aver=sum/count;text2.setText(null);text2.append("\n和:"+sum);text2.append("\n平均值:"+aver);}}5．importjava.applet.*;importjava.awt.*;importjava.awt.event.*;publicclassXiti5{ publicstaticvoidmain(Stringargs[]){ComputerFramefr=newComputerFrame();fr.setTitle("计算");}}classComputerFrameextendsFrameimplementsActionListener{TextFieldtext1,text2,text3;Buttonbutton1,button2,button3,button4;Labellabel;publicComputerFrame(){setLayout(newFlowLayout());text1=newTextField(10);text2=newTextField(10);text3=newTextField(10);label=newLabel("",Label.CENTER);label.setBackground(Color.green);add(text1);add(label);add(text2);add(text3);button1=new");button2=new");button3=new");button4=new");add(button1);add(button2);add(button3);add(button4);button1.addActionListener(this);button2.addActionListener(this);button3.addActionListener(this);button4.addActionListener(this);setSize(300,320);setVisible(true);addWindowListener(newWindowAdapter(){ publicvoidwindowClosing(WindowEvente){ System.exit(0);validate();}

}});publicvoidactionPerformed(ActionEvente){doublen;if(e.getSource()==button1){ doublen1,n2;try{n1=Double.parseDouble(text1.getText());n2=Double.parseDouble(text2.getText());n=n1+n2;text3.setText(String.valueOf(n));label.setText("+");}catch(NumberFormatExceptionee){text3.setText("请输入数字字符");}}elseif(e.getSource()==button2){ doublen1,n2;try{ n1=Double.parseDouble(text1.getText());n2=Double.parseDouble(text2.getText());n=n1-n2;text3.setText(String.valueOf(n));label.setText("-");}catch(NumberFormatExceptionee){text3.setText("请输入数字字符");}}elseif(e.getSource()==button3){doublen1,n2;try{n1=Double.parseDouble(text1.getText());n2=Double.parseDouble(text2.getText());n=n1*n2;text3.setText(String.valueOf(n));label.setText("*");}catch(NumberFormatExceptionee){text3.setText("请输入数字字符");}}elseif(e.getSource()==button4){doublen1,n2;try{n1=Double.parseDouble(text1.getText());n2=Double.parseDouble(text2.getText());n=n1/n2;text3.setText(String.valueOf(n));label.setText("/");}catch(NumberFormatExceptionee){text3.setText("请输入数字字符");}}validate();}}6．importjava.awt.*;importjava.awt.event.*;importjavax.swing.*;publicclassXiti6{ publicstaticvoidmain(Stringargs[]){ newWindowPanel();}}classMypanelextendsJPanelimplementsActionListener{ Buttonbutton;TextFieldtext;Mypanel(){ button=newButton("");text=newTextField(12);add(button);add(text);button.addActionListener(this);}publicvoidactionPerformed(ActionEvente){ Stringname=text.getText();if(name.length()>0)button.setLabel(name);validate();}}classWindowPanelextendsFrame{ Mypanelpanel1,panel2;WindowPanel(){panel1=newMypanel();panel2=newMypanel();panel1.setBackground(Color.red);panel2.setBackground(Color.blue);add(panel1,BorderLayout.SOUTH);add(panel2,BorderLayout.NORTH);setSize(300,320);setVisible(true);addWindowListener(newWindowAdapter(){ publicvoidwindowClosing(WindowEvente){ System.exit(0);validate();}

}});}7．参见10.13,参照本章例子10.21。8．importjava.awt.*;importjava.awt.event.*;importjavax.swing.*;publicclassXiti8{publicstaticvoidmain(Stringargs[]){ MoveFramef=newMoveFrame();f.setBounds(12,12,300,300);f.setVisible(true);f.setTitle("移动");f.validate();f.addWindowListener(newWindowAdapter(){ publicvoidwindowClosing(WindowEvente){ System.exit(0);}});}}classMoveFrameextendsJFrameimplementsActionListener{ uttoncontrolButton,movedButton;publicMoveFrame(){ controlButton=new");controlButton.addActionListener(this);movedButton=newutton();movedButton.setBackground(newColor(12,200,34));setLayout(null);add(controlButton);add(movedButton);controlButton.setBounds(10,30,130,30);movedButton.setBounds(100,100,10,10);}publicvoidactionPerformed(ActionEvente){ intx=movedButton.getBounds().x;inty=movedButton.getBounds().y;x=x+5;y=y+1;if(x>200){x=100;y=100;}}}9．importjava.awt.*;importjava.awt.event.*;publicclassXiti9{ publicstaticvoidmain(Stringargs[]){ Winwin=newWin();}}classWinextendsFrameimplementsKeyListener{ Buttonb[]=newButton[8];intx,y;Win(){setLayout(newFlowLayout());for(inti=0;i<8;i++){b[i]=newButton(""+i);b[i].addKeyListener(this);add(b[i]);}addWindowListener(newWindowAdapter(){publicvoidwindowClosing(WindowEvente){System.exit(0);setBounds(10,10,300,300);setVisible(true);validate();}

}});publicvoidkeyPressed(KeyEvente){ intmoveDistance=1;Componentcom=(Component)e.getSource();intx=(int)com.getBounds().x;inty=(int)com.getBounds().y;Componentcomponent[]=this.getComponents();if(e.getKeyCode()==KeyEvent.VK_UP){ y=y-moveDistance;com.setLocation(x,y);RectanglecomRect=com.getBounds();for(intk=0;k<component.length;k++){ RectangleorthRect=component[k].getBounds();{ y=y+moveDistance;com.setLocation(x,y);break;}}if(y<=0)y=10;}elseif(e.getKeyCode()==KeyEvent.VK_DOWN){ y=y+moveDistance;RectanglecomRect=com.getBounds();for(intk=0;k<component.length;k++){ RectangleorthRect=component[k].getBounds();{ y=y-moveDistance;com.setLocation(x,y);break;}}if(y>=300)y=300;}elseif(e.getKeyCode()==KeyEvent.VK_LEFT){ x=x-moveDistance;com.setLocation(x,y);RectanglecomRect=com.getBounds();for(intk=0;k<component.length;k++){ RectangleorthRect=component[k].getBounds();{ x=x+moveDistance;com.setLocation(x,y);break;}}if(x<=0)x=0;}elseif(e.getKeyCode()==KeyEvent.VK_RIGHT){ x=x+moveDistance;com.setLocation(x,y);RectanglecomRect=com.getBounds();for(intk=0;k<component.length;k++){ RectangleorthRect=component[k].getBounds();{ x=x-moveDistance;com.setLocation(x,y);break;}}if(x>=300)x=300;}}publicvoidkeyTyped(KeyEvente){}publicvoidkeyReleased(KeyEvente){}}习题111．A2．importjava.awt.event.*;importjava.awt.*;importjavax.swing.*;classDwindowextendsFrameimplementsActionListener{ TextFieldinputNumber;TextAreasave;Dwindow(Strings){super(s);inputNumber=newTextField(22);inputNumber.addActionListener(this);save=newTextArea(12,16);setLayout(newFlowLayout());add(inputNumber);add(save);setBounds(60,60,300,300);setVisible(true);validate();addWindowListener(newWindowAdapter(){ publicvoidwindowClosing(WindowEvente){ System.exit(0);}});}publicvoidactionPerformed(ActionEventevent){ Strings=inputNumber.getText();doublen=0;try{ if(n>1000){ intselect=JOptionPane.showConfirmDialog(this,"1000确认正确吗？","",if(select==JOptionPane.YES_OPTION){ save.append("\n"+s);}

JOptionPane.YES_NO_OPTION);else

{ inputNumber.setText(null);}}else

{ save.append("\n"+s);}}catch(NumberFormatExceptione){ JOptionPane.WARNING_MESSAGE);inputNumber.setText(null);}}}publicclassE{ publicstaticvoidmain(Stringargs[]){ newDwindow("");}}3．参照以下例子完成Xiti3.javapublicclassXiti3{publicstaticvoidmain(Stringargs[]){WindowColorwin=newWindowColor();win.setTitle("带颜色对话框的窗口");}}WindowColor.javaimportjava.awt.event.*;importjava.awt.*;importjavax.swing.*;publicclassWindowColorextendsJFrameimplementsActionListener{uttonbutton;WindowColor(){button=newutton("打开颜色对话框");button.addActionListener(this);setLayout(newFlowLayout());add(button);setBounds(60,60,300,300);setVisible(true);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}publicvoidactionPerformed(ActionEvente){ColornewColor=JColorChooser.showDialog(this,"调色板",button.getBackground());if(newColor!=null){button.setBackground(newColor);}}}习题12FileInputStream流。FileInputStream按字节读取文件，FileReader按字符读取文件。3．不能。使用对象流写入或读入对象时，要保证对象是序列化的。么用对象输入流读回的对象一定是原对象的一个克隆。6．importjava.io.*;publicclassXiti6{ publicstaticvoidmain(Stringargs[]){ Filef=newFile("E.java");;try{ RandomAccessFilerandom=newRandomAccessFile(f,"rw");random.seek(0);longm=random.length();while(m>=0){ m=m-1;random.seek(m);intc=random.readByte();if(c<=255&&c>=0)((char)c);}else{ m=m-1;random.seek(m);bytecc[]=newbyte[2];random.readFully(cc);System.out.print(newString(cc));}}}catch(Exceptionexp){}}}7．importjava.io.*;publicclassXiti7{ publicstaticvoidmain(Stringargs[]){ Filefile=newFile("E.java");FiletempFile=newFile("temp.txt");try{FileReader inOne=newFileReader(file);BufferedReaderinTwo=newBufferedReader(inOne);FileWritertofile=newFileWriter(tempFile);BufferedWriterout=newBufferedWriter(tofile);Strings=null;inti=0;s=inTwo.readLine();while(s!=null){ i++;out.write(i+""+s);out.newLine();s=inTwo.readLine();}inOne.close();inTwo.close();out.flush();out.close();tofile.close();}catch(IOExceptione)(e);}}}8．属于操作题目，解答略。9．importjava.util.*;importjava.io.*;importjava.awt.*;importjava.awt.event.*;importjavax.swing.*;publicclassXiti9{ publicstaticvoidmain(Stringargs[]){ EWindoww=newEWindow();w.validate();}}classEWindowextendsFrameimplementsActionListener,ItemListener{ Stringstr[]=newString[7],s;FileReaderfile;BufferedReaderin;Buttonstart,next;Checkboxcheckbox[];TextField题目,分数;intscore=0;CheckboxGroupage=newCheckboxGroup();EWindow(){ super("");分数=new=newTextField(70);start=new");start.addActionListener(this);next=new");next.addActionListener(this);checkbox=newCheckbox[4];for(inti=0;i<=3;i++){checkbox[i]=newCheckbox("",false,age);checkbox[i].addItemListener(this);}try{ file=newFileReader("English.txt");in=newBufferedReader(file);}catch(IOExceptione){}setBounds(20,100,660,300);setVisible(true);Boxbox=Box.createVerticalBox();Panelp1=newPanel(),p2=newPanel(),p3=newPanel(),p4=newPanel(),p5=newPanel();p1.add(newLabel("题目:"));p1.add(题目);p2.add(newLabel("选择答案："));for(inti=0;i<=3;i++){ p2.add(checkbox[i]);}p3.add(newLabel("您的得分:"));p3.add(分数);p4.add(start);p4.add(next);box.add(p1);box.add(p2);box.add(p3);box.add(p4);addWindowListener(newWindowAdapter(){publicvoidwindowClosing(WindowEvente){ System.exit(0);}});add(box,BorderLayout.CENTER);reading();}publicvoidreading(){ inti=0;try{s=in.readLine();if(!(s.startsWith("endend"))){ StringTokenizertokenizer=newStringTokenizer(s,"#");while(tokenizer.hasMoreTokens()){ str[i]=tokenizer.nextToken();i++;}题目.setText(str[0]);for(intj=1;j<=4;j++){ checkbox[j-1].setLabel(str[j]);}}elseif(s.startsWith("endend")){ ");for(intj=0;j<4;j++){ checkbox[j].setLabel("end");in.close();file.close();}}}catch(Exceptionexp){题目.setText("无试题文件");}}publicvoidactionPerformed(ActionEventevent){ if(event.getSource()==start){ score=0;分数.setText("得分："+score);try{ file=newFileReader("English.txt");in=newBufferedReader(file);}catch(IOExceptione){}reading();}if(event.getSource()==next){ reading();for(intj=0;j<4;j++){ checkbox[j].setEnabled(true);}}}publicvoiditemStateChanged(ItemEvente){ for(intj=0;j<4;j++){if(checkbox[j].getLabel().equals(str[5])&&checkbox[j].getState()){ score++;分数.setText("得分："+score);}checkbox[j].setEnabled(false);}}}习题1312．8。ABCD。HashMap<K,V>来存储。5．importjava.util.*;classUFlashKeyimplementsComparable{doubled=0;UFlashKey(doubled){this.d=d;}publicintcompareTo(Objectb){UFlashKeyst=(UFlashKey)b;if((this.d-st.d)==0)return-1;elsereturn(int)((this.d-st.d)*1000);}}classUFlash{Stringname=null;doublecapacity,price;UFlash(Strings,doublem,doublee){name=s;price=e;}}publicclassXiti5{publicstaticvoidmain(Stringargs[]){TreeMap<UFlashKey,UFlash>treemap=newTreeMap<UFlashKey,UFlash>();Stringstr[]={"U1","U2","U3","U4","U5","U6","U7","U8","U9","U10"};doublecapacity[]={1,2,2,4,0.5,10,8,4,4,2};doubleprice[]={30,66,90,56,50,149,120,80,85,65};UFlashUFlash[]=newUFlash[10];for(intk=0;k<UFlash.length;k++){UFlash[k]=newUFlash(str[k],capacity[k],price[k]);}UFlashKeykey[]=newUFlashKey[10];for(intk=0;k<key.length;k++){key[k]=newUFlashKey(UFlash[k].capacity);//关键字按容量成绩排列大小}for(intk=0;k<UFlash.length;k++){treemap.put(key[k],UFlash[k]);}intnumber=treemap.size();System.out.p