基础作业附答案

1、1. X (x<1) Y= 2x-1 (1<x<10) 3x-11 (x>10) 要求输入x值后，输出y值。package student.xiaoqiao.day01;；public class Yi public static void main(String args) System.out.println("请输入一个数");Scanner sc = new Scanner(System.in);int x = sc.nextInt();if (x < 1) System.out.println("y=" + x);

2、if (x > 1 & x < 10) System.out.println("y=" + (2 * x - 1);if (x > 10) System.out.println("y=" + (3 * x - 11);2. 输入一个年份判断year是否是闰年package student.xiaoqiao.day01;import java.util.Scanner;public class Er public static void main(String args) System.out.println("请输入年

3、份");Scanner sc=new Scanner(System.in);int year=sc.nextInt();if(year%4=0&year%100!=0)|(year%400=0)System.out.println("是闰年");else System.out.println("不是闰年");3. 任意输入a,b,c 3个数判断a，b，c大小package student.xiaoqiao.day01;import java.util.Scanner;public class San public static void

4、 main(String args) System.out.println("请输入三个数（加空格或回车）:");Scanner sc = new Scanner(System.in);int x = sc.nextInt();int y = sc.nextInt();int z = sc.nextInt();if (x > y & x > z) System.out.println(x); else if (x < y & z < y) System.out.println(y); else if (x < z & y

5、 < z) System.out.println(z);4_1输出图形 * *package student.xiaoqiao.day01;public class Si_1 public static void main(String args) int temp = 3;for (int i = 1; i <= temp; i+) for (int j = 1; j <= temp - i; j+) System.out.print(" ");for (int k = 1; k <= 2 * i - 1; k+) System.out.print

6、("*");System.out.print('n');4_2输出图形* * *package student.xiaoqiao.day01;public class Si_1 public static void main(String args) int temp = 3;for (int i = 1; i <= temp; i+) for (int j = 1; j <= temp - i; j+) System.out.print(" ");for (int k = 1; k <= 2 * i - 1; k+)

7、System.out.print("*");System.out.print('n');4_3输出图形任意输入n当输入n值为1时，输出 *当输入n值为2时，输出 当输入n值为3时，输出 .。当输入n值为5时，输出 * * * * * * *package student.xiaoqiao.day01;import java.util.Scanner;public class Si_3 public static void main(String args) System.out.println("请输入一个数：");Scanner sc=

8、new Scanner(System.in);int temp = sc.nextInt();for (int i = 1; i <= temp; i+) for (int j = 1; j <= temp - i; j+) System.out.print(" ");for (int k = 1; k <= 2 * i - 1; k+) System.out.print("*");System.out.print('n');for (int i = temp; i >= 1; i-) for (int j = i

9、-1; j < temp; j+) System.out.print(" ");for (int k = 1; k <= 2 * i - 3; k+) System.out.print("*");System.out.print('n');4_4 输出图形 * *package student.xiaoqiao.day01;public class Si_4 public static void main(String args) int temp = 3;for (int i = 1; i <= temp; i+) f

10、or (int j = 1; j <= temp - i; j+) System.out.print(" ");for (int k = 1; k <= 2 * i + 1; k+) System.out.print("*");System.out.print('n');4_5 输出图形package student.xiaoqiao.day01;public class Si_5 public static void main(String args) int temp = 4;for (int i = 1; i <=

11、 temp; i+) for (int k = 1; k <= 5; k+) System.out.print("*");System.out.print('n');5. 判断水仙花数 输入一个3位数，判断个位，十位与百位的3次方的和是否等于其本身，相等就是水仙花数package student.xiaoqiao.day01;import java.util.Scanner;public class Wu public static void main(String args) System.out.println("请输入一个三位数&quo

12、t;);Scanner sc = new Scanner(System.in);int a = sc.nextInt();int b = a / 100;int c = (a / 10) % 10;int d = a % 10;if (a = b * b * b + c * c * c + d * d * d) System.out.println("此数是水仙花"); else System.out.println("此数不是水仙花");6. 输入一个x和y，在输入一个字符x, 当输入的字符为+，输出x与y的和，当输入的字符为-，输出x与y的差，当输入

13、的字符为*，输出x与y的积，当输入的字符为/，输出x与y的商.package student.xiaoqiao.day01;import java.util.Scanner;public class Liu public static void main(String args) System.out.println("请输入一个加减乘除字符");Scanner sc=new Scanner(System.in);char c=sc.next().charAt(0);int x=4;int y=2;switch (c) case '+':System.out

14、.println("x+y="+(x+y);break;case '-':System.out.println("x-y="+(x-y);break;case '*':System.out.println("x*y="+(x*y);break;case '/':System.out.println("x/y="+(x/y);break;default:System.out.println("输入的字符不合法！");break;7.求数列 0,1,2

15、,32 ,.,nn-1 的和 要求判断n是否在0到10之间，如果不在提示重新输入，for循环 while循环，do while 都要写一遍。7.1package student.xiaoqiao.day01;import java.util.Scanner;public class Qi public static void main(String args) System.out.println("请输入一个0到10的数字");Scanner sc=new Scanner(System.in);int a=sc.nextInt();if (a>=0&a<

16、;=10) int b=0;for (int i = 1; i <=a; i+) b=(int) (b+Math.pow(i,i-1);System.out.println(b);else System.out.println("输入的数不在0到10之间，请重新输入！");7.2package student.xiaoqiao.day01;import java.util.Scanner;public class Qi_dowhile public static void main(String args) System.out.println("请输入一个

17、0到10的数字");Scanner sc = new Scanner(System.in);int a = sc.nextInt();if (a>=0&a<=10) int b=0;int i=1; dob = (int) (b + Math.pow(i, i-1);i+;while (i<=a); System.out.println(b);else System.out.println("输入的数不在0到10之间，请重新输入！");7.3package student.xiaoqiao.day01;import java.util.S

18、canner;public class Qi_while public static void main(String args) System.out.println("请输入一个0到10的数字");Scanner sc = new Scanner(System.in);int a = sc.nextInt();if (a>=0&a<=10) int b=0;int i=1; while (i<=a) b = (int) (b + Math.pow(i, i-1);i+; System.out.println(b);else System.out

19、.println("输入的数不在0到10之间，请重新输入！");8输出9*9乘法表package student.xiaoqiao.day01;public class Ba public static void main(String args) for (int i = 1; i <=9; i+) for (int j = 1; j <=i; j+) System.out.print(i+"*"+j+"="+i*j+" ");System.out.print('n');9. 输入x,

20、y比较大小，使用三目运算package student.xiaoqiao.day01;import java.util.Scanner;public class Jiu public static void main(String args) System.out.println("请输入两个值：");Scanner sc=new Scanner(System.in);int x=sc.nextInt();int y=sc.nextInt();System.out.println(x>y?"x大于y":"x小于y");Day02

21、作业题目：编写程序实现一个猜数字游戏：系统随机生成一个100以内的整数，用户根据系统提示来进行猜测，如果猜对，则显示“恭喜”并提示“增加难度，需要继续吗？”，如果用户选择继续则系统随机生成一个1000以内的整数，否则系统退出；如果用户猜错，则显示“错误，请重新输入！”，一旦用户连续5次没有猜中，则系统退出！package student.xiaoqiao.Day02;import java.util.Scanner;import java.util.concurrent.CountDownLatch;public class Randomdemo public static void main

22、(String args) int a=(int) (Math.random()*100)+1;/系统随机生成一个1到100的整数System.out.println(a);System.out.println("请输入一个1到100的整数");Scanner sc1=new Scanner(System.in);/从键盘上输入一个数int num1=sc1.nextInt();while(num1!=a) if(num1>a)System.out.println("您输入的数字过大，请重新输入!");if(num1<a)System.out

23、.println("您输入的数字过小，请重新输入!"); num1=sc1.nextInt();if(num1=a) System.out.println("小主好棒,您猜对啦！"+'r'+"请问还要升级难度吗（随机生成1到1000的整数），继续请输入是，退出选择否。"+'r');char ch=sc1.next().charAt(0);if (ch='是') int b=(int) (Math.random()*1000)+1;/系统随机生成一个1到1000的整数System.out.

24、println(b);System.out.println("请输入一个1到1000的整数");int num2=sc1.nextInt();int count=1;while(num2!=b&count<5) System.out.println("错误，请重新输入!"); num2=sc1.nextInt(); count+; if (num2=b) System.out.println("您已输入超过五次，游戏结束！");if (ch='否') System.out.println("游戏

25、结束！");4. 歌手找打分：在歌唱比赛中，共有10位评委进行打分，在计算歌手得分时，去掉一个最高分，去掉一个最低分，然后剩余的8位评委的分数进行平均，就是该选手的最终得分，输入每个评委的评分，求某选手的得分。package student.xiaoqiao.Day02;import java.awt.peer.SystemTrayPeer;import java.util.Scanner;public class Grade public static void main(String args) int qiao =new int10;System.out.println(&qu

26、ot;请输入十位评委成绩(回车确认)：");Scanner scanner = new Scanner(System.in);for(int i=0;i<10;i+)qiaoi=scanner.nextInt();/if(i=9)/System.out.println("停止输入！");/for (int i = 0; i < qiao.length; i+) for (int j = i + 1; j < qiao.length; j+) if (qiaoi < qiaoj) int temp = qiaoi;qiaoi = qiaoj;

27、qiaoj = temp;/System.out.print(qiaoi+" ");int sum = 0;for (int i = 1; i < 9; i+) sum = sum + qiaoi;System.out.println(sum / 8.0);-1. /* 字符串比较空间的里值，* 1、输入89.9543 四舍五入 (1)保留2位 (2) 取整四舍五入-math方法package student.xiaoqiao.Day02;public class Yi_sishewuru public static void main(String args) do

28、uble a=89.9543;System.out.println(Math.round(a*100 )/100.0);System.out.println(Math.round(a); * 2、已经字符串“this is a test of java” * （1）统计该字符串s出现的次数 * （2）取出字符串中“test” * （3）将字符串中每个单词的第1个字符，变成大写输出。 * （4）用两种方式实现该字符串的倒叙输出（用StringBuffer和for实现） * (5)算出字符串中字母、数字、空格各多少package student.xiaoqiao.Day02;public clas

29、s Er_Zifuchuan public static void main(String args) int count=0;String str="this is a test of java"for(int k=0;k<str.length();k+)String a1 = str.substring(k,k+1);if(a1.equals("s")count+;System.out.println(count);System.out.println(str.substring(10, 14);String a2=str.split(&quo

30、t; ");StringBuffer a4=new StringBuffer();for(int k=0;k<a2.length;k+)a4.append(a2k.substring(0, 1).toUpperCase()+a2k.substring(1)+" ");System.out.println(a4.toString();StringBuffer a5 = new StringBuffer(str);System.out.println(a5.reverse();for(int k=0;k<str.length();k+)System.out

31、.print(str.substring(str.length()-1-k,str.length()-k)+"");int englishCount=0;int spaceCount=0;int numCount=0;char aa=str.toCharArray(); for (int i = 0; i < aa.length; i+) if (Character.isLetter(aai) englishCount+;else if (Character.isSpaceChar(aai) spaceCount+;else if (Character.isDigit

32、(aai) numCount+;System.out.println();System.out.println("字母的个数："+englishCount);System.out.println("空格的个数："+spaceCount);System.out.println("数字的个数："+numCount); * 3、输入某年某月某日，判断这一天是这一年的第几天(date)package student.xiaoqiao.Day02;/import java.text.SimpleDateFormat;/import java.u

33、til.Date;/public class San_Date /public static void main(String args) /Date d=new Date();/SimpleDateFormat sim=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");/String ss=sim.format(d);/System.out.println(ss);/import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Ca

34、lendar;import java.util.Date;import java.util.Scanner;public class San_Date public static void main(String args) try Scanner sc = new Scanner(System.in);System.out.print("输入时间(格式:yyyy-MM-dd)");String str = sc.nextLine();SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd");Date

35、 d = f.parse(str);Calendar c = Calendar.getInstance();c.setTime(d);System.out.println(str + "是这一年的第" + c.get(Calendar.DAY_OF_YEAR)+ "天"); catch (ParseException e) e.printStackTrace(); * 4、输入3个数由小到大的排序import java.util.Scanner;public class Si_paixu public static void main(String ar

36、gs) System.out.println("请输入三个数：");int qiao = new int3;Scanner scanner = new Scanner(System.in);for (int i = 0; i < 3; i+) qiaoi = scanner.nextInt();for (int i = 0; i < qiao.length; i+) for (int j = i + 1; j < qiao.length; j+) if (qiaoi > qiaoj) int temp = qiaoi;qiaoi = qiaoj;qi

37、aoj = temp;System.out.print(qiaoi + " "); * 5、编写一个截取字符串的函数，输入为一个字符串和字节数输出为按字截取的字符串。但是要保证汉字不被截半个，如：“我ABC”4，应该截为“我AB”，输入“我ABC汉DEF”6， * 应该输出为“我ABC”，而不是ABC+汉的半个。（有点复杂可以先做别的） */package com.day02;public class Test05 public static void main(String args) / TODO Auto-generated method stubString ss

38、= getString("s我是DW", 4);/ 调用ss=getString("我ABC汉DEF",6);System.out.println(ss);/拼接/StringBuffer sss=new StringBuffer();/sss.append("akd");/sss.append(ss.charAt(0);public static String getString(String s, int n) int index = 0;/ 定义游标位置StringBuffer ss = new StringBuffer();/

39、 用来存放新的值for (int i = 0; i <= n - 1; i+) if (s.charAt(index) < 255 && s.charAt(index) > 0| Character.isDigit(s.charAt(index) / 如果当前字符是数字字符ss.append(s.charAt(index);/append:参数将被追加到此序列。此序列的长度将增加 1。index+; else / 如果当前字符是汉字if (index <= n - 2) / ss.append(s.charAt(index);/charAt(index)

40、返回指定索引处的 char 值。index+;n-;/ 当遇到汉字以后，因汉字占两个字节，n自动减1，例如"s我"总共占3个字节，"n"代表所取字节数，这时候已经占用了3个字节，当需要取2个/ 字节时,”s我“是点3个字节，"我"自动取消,当需要取4个字节时，”s我是“是占用5个字节，return ss.toString();6. 将十进制数35转换为二进制数package student.xiaoqiao.Day03;public class Liu_shijinzhi public static void main(String

41、args) System.out.println(Integer.toBinaryString(35);7. 将字符串数组按字典的顺序重新排列"Java","Basic ","C+"," Fortran","SmallTalk"package student.xiaoqiao.Day03;import java.util.Arrays;public class QI_paixu public static void main(String args) String s=new String5;s

42、0="Java"s1="Basic"s2="C+"s3="Fortran"s4="SmallTalk"Arrays.sort(s);System.out.println(Arrays.toString(s);8.输出杨辉三角 效果图如下package student.xiaoqiao.Day03;import java.util.Scanner;public class Ba_yanghui public static void main(String args) System.out.prin

43、tln("请输入一个整数：");Scanner sc=new Scanner(System .in);int b=sc.nextInt();int a = new intbb; for (int i = 0; i < b; i+) aii = 1; ai0 = 1;for (int i = 2; i <b; i+) for (int j = 1; j < i; j+) aij = ai - 1j - 1 + ai - 1j;for (int i = 0; i <b; i+) /for (int k = 0; k < 2 * (2*b - i)

44、- 1; k+) /System.out.print(" ");/for (int j = 0; j <=i; j+) System.out.print(aij + " ");System.out.println();9（附加题）输出N*N方阵N输入为1时N输入为2时。N输入为5时/* * 2）、假设N=5,显示5*5的方阵的转圈结果 * 1 2 3 4 5 * 16 17 18 19 6 * 15 24 25 20 7 * 14 23 22 21 8 * 13 12 11 10 9 * * 1、判断有多少个外循环， * 2、四个for循环输出 *

45、/package com.day03Home;import java.util.Scanner;public class Test09 public static void main(String args) / TODO Auto-generated method stubint k=1;Scanner sc=new Scanner(System.in);System.out.print("请输入N*N方阵的数为：");int N=sc.nextInt();int a=new intNN;for(int i=0;i<=N/2;i+)for(int j=i;j<

46、N-i;j+) /0-4 1-3 2-2aij=k+;for(int j=i+1;j<N-i;j+) /1-4 2-3ajN-i-1=k+;for(int j=N-i-2;j>=i;j-) /3-0 2-1aN-i-1j=k+;for(int j=N-i-2;j>i;j-) /3-1aji=k+;for(int i=0;i<a.length;i+)for(int j=0;j<a.length;j+)System.out.print(aij+"t");System.out.println();10.五子棋游戏11. 用递归来实现5！=5*4！=5

47、*4*3！=5*4*3*2！=5*4*3*2*1输出5！的值package student.xiaoqiao.Day03;public class Shiyi_digui public static int fn(int n) if (n <= 1) return 1;else return n * fn(n - 1);public static void main(String args) System.out.println("5!="+fn(5);12. 0、1、1、2、3、5、8、13、21、34、在数学上，斐波纳契数列以如下被以递归的方法定义：F（0）=0，

48、F（1）=1，F（n）=F(n-1)+F(n-2)（n2）package student.xiaoqiao.Day03;import java.util.Scanner;public class Shier_Fn public static int fn(int n)if (n=0) return 0;else if (n=1) return 1;else return fn(n-1)+fn(n-2);public static void main(String args) System.out.println("请输入一个数：");Scanner scanner=new Scanner(System.in);int a=scanner.nextInt();System.out.println(fn(a);13. 1二分法.package student.xiaoqiao.Day04;import java.util.Scanner;public class Erfen public static void main(String args) int a = 1, 21, 25, 44