61Java面向对象程序设计_习题解答(耿祥义)

1书后习题参考答案习题1............................................................................................................................................2习题2............................................................................................................................................3习题3............................................................................................................................................4习题4..........................................................................................................................................10习题5...........................................................................................................................................11习题6..........................................................................................................................................14习题7..........................................................................................................................................15习题9..........................................................................................................................................16习题12........................................................................................................................................20习题13........................................................................................................................................25习题14........................................................................................................................................27习题15........................................................................................................................................28习题16........................................................................................................................................31习题17........................................................................................................................................392习题11．JamesGosling2．（1）使用一个文本编辑器编写源文件。（2）使用Java编译器（javac.exe）编译Java源程序，得到字节码文件。命令：javac–d.文件名称.java（3）使用Java解释器（java.exe）运行Java程序。命令：java包名.类名3．Java的源文件是由若干个书写形式互相独立的类、接口、枚举等组成。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．新建JAVA_HOME系统环境变量，指向安装目录在系统环境变量path中增加内容：%JAVA_HOME%\bin;新建系统环境变量classpath并填入三项：.;%JAVA_HOME%\lib\dt.jar;%JAVA_HOME%\lib\tools.jar5．B6．Java源文件的扩展名是.java。Java字节码的扩展名是.class。7．D8．（1）Speak.java（2）生成两个字节码文件，这些字节码文件的名字Speak.class和Xiti8.class（3）javaXiti8（4）执行javaSpeak的错误提示Exceptioninthreadmainjava.lang.NoSuchMethodError:main执行javaxiti8得到的错误提示Exceptioninthreadmainjava.lang.NoClassDefFoundError:xiti8(wrongname:Xiti8)执行javaXiti8.class得到的错误提示Exceptioninthreadmainjava.lang.NoClassDefFoundError:Xiti8/class执行javaXiti8得到的输出结果I'mgladtomeetyou9．属于操作题，解答略。3习题21．BD2．【代码1】【代码2】错误//【代码3】更正为floatz=6.89F;3．float型常量后面必须要有后缀“f”或“F”。对于double常量，后面可以有后缀“d”或“D”，但允许省略该后缀。4．publicclassXiti4{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．数组名字.length6．数组名字.length7．【代码1】A,65【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】3【代码5】4.4【代码6】8.84习题31．输出110if-else语句书写的不够规范，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，结果赋给startPositionendPosition=(int)cEnd;//cEnd做int型转换运算，结果赋给endPositionSystem.out.println(俄文字母表：);for(inti=startPosition;i=endPosition;i++){charc='\0';c=(char)i;//i做char型转换运算，并将结果赋值给cSystem.out.print(+c);//System.out.print(+c++Integer.toHexString(c));if((i–startPosition+1)%10==0){System.out.println();}}}}4．随书给出的解答：publicclassXiti4{publicstaticvoidmain(Stringargs[]){doublesum=0,a=1;inti=1;while(i=20){sum=sum+a;i++;a=a*i;}System.out.println(sum=+sum);}}结果：sum=2.5613274941118203E18如果sum改成long的情况？？？1!=12!=23!=64!=245!=1206!=7207!=50408!=403209!=36288010!=362880011!=3991680012!=47900160013!=622702080014!=8717829120015!=130767436800016!=2092278988800017!=35568742809600018!=640237370572800019!=12164510040883200020!=2432902008176640000sum=2561327494111820313262412072050404032036288036288003991680047900160062270208008717829120013076743680002092278988800035568742809600064023737057280001216451004088320002432902008176640000-4249290049419214848sum=25613274941118203135精确计算的方法：[书P201有类似操作]BigIntegersum=newBigInteger(0);BigIntegerfactorial=newBigInteger(1);for(inti=0;i20;){i++;factorial=factorial.multiply(newBigInteger(String.valueOf(i)));System.out.println(i+!=+factorial);sum=sum.add(factorial);}System.out.println(sum=+sum);//256-1327-4941-1182-0313//System.out.println(Long.MAX_VALUE);922-3372-0368-5477-58075．classXiti5{publicstaticvoidmain(Stringargs[]){for(intj=2;j=100;j++){inti=0;for(i=2;i=j/2;i++){if(j%i==0)break;}if(ij/2){System.out.print(+j);}}}}6．classXiti6{publicstaticvoidmain(Stringargs[]){doublesum=0;doublereciprocalFactorial=1;for(inti=1;i=20;i++){rec