javaee基础教程习题答案.docx
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javaee基础教程习题答案.docx
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javaee基础教程习题答案
JAVAEE基础教程课后部分编程题答案
2-14publicclassaa{
publicstaticvoidmain(String[]args){
//TODOAuto-generatedmethodstub
doublex=34.5;
doubley=68.4;
doublez=x+y;
System.out.println("x+y="+x+"+"+y+"="+z);}
}
3-19
(一)从大到小
插入排序法
publicclassSort{
publicstaticvoidmain(String[]args){
int[]A={30,1,-9,70,25};
for(inti=1;i for(intj=i;j>0;j--){ if(A[j]>A[j-1]){ inttemp; temp=A[j-1]; A[j-1]=A[j]; A[j]=temp; } } } System.out.println("利用插入排序方法的结果是: "); for(inti=0;i System.out.print(A[i]+","); } } } 选择排序法 publicclassS_sort{ publicstaticvoidmain(String[]args){ int[]A={30,1,-9,70,25}; intmax,temp; for(inti=A.length-1;i>0;i--){ max=0; for(intj=1;j<=i;j++){ if(A[max]>A[j]) max=j; } temp=A[max]; A[max]=A[i]; A[i]=temp; } System.out.println("利用选择排序方法的结果是: "); for(inti=0;i System.out.print(A[i]+","); } } } (二)从小到大 importjava.util.*; publicclassrr{ publicstaticvoidmain(String[]args){ intA[]={30,1,-9,70,25}; Arrays.sort(A); for(inti=0;i<5;i++){ System.out.print(A[i]+","); } } } 3-11publicclasspp{ publicstaticvoidmain(String[]args){ inti,j,count=0; for(j=2;j<=1000;j++){ for(i=2;i<=j/2;i++){ if(j%i==0) break; } if(i>j/2) { count++;System.out.print(j+"\t"); if(count%5==0) System.out.println("");} } } } 3-12importjava.util.Random; publicclassrr{ publicstaticvoidmain(String[]args){ intcount1=0,count2=0,count3=0,count4=0,count5=0,count6=0; inttemp; Randomr=newRandom(); for(inti=1;i<=100;i++){ temp=r.nextInt()%6+1; switch(temp){ case1: count1++;break; case2: count2++;break; case3: count3++;break; case4: count4++;break; case5: count5++;break; case6: count6++;break; } } System.out.println("count1="+count1); System.out.println("count2="+count2); System.out.println("count3="+count3); System.out.println("count4="+count4); System.out.println("count5="+count5); System.out.println("count6="+count6); } } 3-13publicclassrr{ publicstaticvoidmain(String[]args){ intsum=0,a=1; for(inti=1;i<16;i++){ a=a*i; sum+=a; } System.out.println("1! +2! +3! +...+15! ="+sum); } } 3-16publicclassr{ publicstaticvoidmain(String[]args){ int[]prime=newint[30]; inti,j,m=0,count=0; for(j=2;count<30;j++){ for(i=2;i<=j/2;i++){ if(j%i==0) break;} if(i>j/2){ count++; prime[m]=j; System.out.print(prime[m]+","); } } } } 3-18importjava.util.Scanner; importjava.util.*; publicclassyy{ /** *@paramargs */ publicstaticvoidmain(String[]args){ //TODOAuto-generatedmethodstub int[]d=newint[100]; inti=-1; do{ System.out.println("输入整数(-2结束): "); Scannerinput=newScanner(System.in); i++; d[i]=input.nextInt();} while(d[i]! =-2); int[]dd=newint[i]; for(intj=0;j {dd[j]=d[j]; } Arrays.sort(dd); System.out.print("输入值按从小到大的顺序排序是"); for(inta: dd) System.out.print(a+""); } } 6-12importjava.util.Calendar; publicclassCalendarExample{ publicstaticvoidmain(String[]args){ Calendarcal=Calendar.getInstance(); cal.add(Calendar.DATE,10); System.out.println("十天后的日期和时间: "); System.out.println(cal.get(Calendar.YEAR)+"年" +(cal.get(Calendar.MONTH)+1)+"月" +cal.get(Calendar.DATE)+"日" +cal.get(Calendar.HOUR)+": " +cal.get(Calendar.MINUTE)+": " +cal.get(Calendar.SECOND)); } } 6-15importjava.util.HashMap; importjava.util.Map; publicclasspp{ publicstaticvoidmain(Stringargs[]){ Map map.put("张三","90分"); map.put("李四","83分"); System.out.println("所查的学生有: "+map.keySet()); System.out.println("张三的成绩为: "+map.get("张三")); System.out.println("李四的成绩为: "+map.get("李四")); System.out.println(); map.put("李四","100分"); System.out.println("修改后李四的成绩为: "+map.get("李四")); System.out.println(); System.out.println("两人最终成绩为: "); System.out.println("张三: "+map.get("张三")); System.out.println("李四: "+map.get("李四")); } } 6-17 publicclasse{ publicstaticvoidmain(String[]args){ longx=987654; Stringstr1=String.valueOf(x);//使用String类的valueOf()方法实现数值到字符串的转换 inty=365; Stringstr2=Integer.toString(y,16);//转换为十六进制 System.out.println("987654转换成字符串为: "+str1+"\n"); System.out.println("十进制365转换为十六进制为: "+str2); } } 6-21importjava.io.IOException; importjava.util.Scanner; importjava.util.List; importjava.util.ArrayList; importjava.util.InputMismatchException; classPerson{ privateStringname; privateintphone; publicStringgetName(){ returnname; } publicintgetPhone(){ returnphone; } publicPerson(Stringname,intphone){ this.name=name; this.phone=phone; } publicStringtoString(){ returnname+"的电话号码为: "+phone; } } publicclasspp{ publicstaticvoidmain(Stringargs[])throwsIOException{ charm; do{ List Scannerinput=newScanner(System.in); System.out.println("请输入同学的姓名和联系方式: "); try{StringPname=input.next(); intPhone=input.nextInt(); PersonLX=newPerson(Pname,Phone); list.add(LX); for(Personp: list){ System.out.println(p);} } catch(InputMismatchExceptione1) {System.out.println("警告: 您输入的值不合理! ");} catch(Exceptione2) {System.out.println("警告: 其它异常! ");} System.out.println("是否继续输入? Y/N"); m=(char)System.in.read(); }while(m=='y'||m=='Y'); } } 6-22importjava.util.HashMap; importjava.util.Map; importjava.util.Scanner; publicclasspp{ publicstaticvoidmain(String[]args){ Map map.put("ample","足够的、宽敞的"); map.put("brisk","轻快的、兴隆的"); map.put("deem","认为、视为"); map.put("doom","注定、劫数"); map.put("gossip","流言飞语"); map.put("lame","蹩脚的"); map.put("oath","誓言"); map.put("reap","收割、收获"); map.put("shabby","破旧的、不公正的"); map.put("ecology","生态、生态学"); while(true){ Scannersc=newScanner(System.in); System.out.println("请输入单词"); Stringstr=sc.next(); System.out.println("你输入的单词的中文含义是: "+"\t"+map.get(str)); } } } 8-10importjava.io.BufferedReader; importjava.io.IOException; importjava.io.FileReader; importjava.io.FileNotFoundException; publicclassrr{ publicStringreadfile(){ Stringstr1=""; BufferedReaderfr; try{ fr=newBufferedReader(newFileReader("java.txt")); Stringm=fr.readLine(); while(m! =null){ str1+=m+"\n"; m=fr.readLine(); StringBuffers1=newStringBuffer(str1); System.out.println(s1); } fr.close(); }catch(FileNotFoundExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } returnstr1; } publicstaticvoidmain(String[]args){ rrr=newrr(); Stringstr1=r.readfile(); StringBufferstr2=newStringBuffer(str1); str2.reverse(); System.out.println(str2); } } 8-14importjava.io.BufferedReader; importjava.io.File; importjava.io.FileNotFoundException; importjava.io.FileReader; importjava.io.FileWriter; importjava.io.IOException; importjava.util.Arrays; importjava.util.Scanner; classs{ publicstaticvoidmain(String[]args){ try{ Filef1=newFile("file1.txt"); Filef2=newFile("file2.txt"); FileReaderfr1=newFileReader(f1); FileReaderfr2=newFileReader(f2); BufferedReaderbr1=newBufferedReader(fr1); BufferedReaderbr2=newBufferedReader(fr2); Stringlen1=br1.readLine(); Stringlen2=br2.readLine(); Scannerscan1=newScanner(len1); Scannerscan2=newScanner(len2); scan1.useDelimiter(","); scan2.useDelimiter(","); int[]I=newint[9]; for(intj=0;j<=4;j++){ I[j]=scan1.nextInt(); } for(intj=0;j<=3;j++){ I[j+5]=scan2.nextInt(); } Arrays.sort(I); System.out.print(Arrays.toString(I)); fr1.close(); fr2.close(); Filef3=newFile("file3.text"); FileWriterfw=newFileWriter(f3); for(inta: I) { fw.write(a+","); } fw.close(); }catch(FileNotFoundExceptione){ e.printStackTrace(); }catch(IOExceptione){ e.printStackTrace(); } } } 9-6 法一classtt{ publicstaticsynchronizedvoidttt(){ inti=10; while(true){ System.out.print(i++); try{ Thread.sleep(500); }catch(InterruptedExceptione){ e.printStackTrace(); } if(i==16){ System.out.println(); break; } System.out.print(","); } } } publicclasstimplementsRunnable{ publicvoidrun(){ tt.ttt(); } publicstaticvoidmain(String[]args){ Threadt1=newThread(newt(),"xiancheng1"); Threadt2=newThread(newt(),"xiancheng2"); t1.start(); t2.start(); } } 法二classPrintnum{ publicvoidshownum(){ inti=10; while(true){ try{ System.out.print(i); if(i==15){ System.out.println(); break; } System.out.print(","); Thread.sleep(500); }catch(InterruptedExceptione){ e.printStackTrace(); } i++; } } } publicclassTest9_6implementsRunnable{ privatestaticPrintnummyprint=newPrintnum(); publicvoidrun(){ synchronized(myprint){ myprint.shownum(); } } publicstaticvoidmain(String[]args){ Threadt1=newThread(newTest9_6(),"线程1"); t1.start(); Threadt2=newThread(newTest9_6(),"线程2"); t2.start(); } } 法三classPrint{ publicstaticsynchronizedvoidprint(){ for(inti=10;i<16;i++){ System.out.print(i+","); try{ Thread.sleep(500); }catch(InterruptedExceptione){ //TODOAuto-generatedcatchblock e.printStackTrace(); } } } } publicclasstimplementsRunnable{ public
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