Java练习题2-代码

代码练习题

练习1：键盘输入一个年份和月份，判断当月多少天？

import java.util.Scanner; public class demo1{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入年份");                   int year = scan.nextInt() ; System.out.println("请输入月份");                   int month = scan.nextInt() ;                   switch(month){                           case 1:                           case 3:                                                case 5:                                                         case 7:                                                         case 8:                                                                  case 10:                           case 12:                                    System.out.println("你输入的月份有31天");                                    break;                           case 2:                                    if( (year%4 == 0 && year%100 != 0) || (year%400 == 0) ) {                                             System.out.println("您输入的月份有28天");                                    }else{                                             System.out.println("您输入的月份有29天");                                    }break;                           case 4:                           case 6:                                                case 9:                                                         case 11:                                                                System.out.println("你输入的月份有30天");                                    break;                           default:                                    System.out.println("你输入的月份有误");                                    break;                   }          } }

练习2：循环得到用户从控制台输入的5个整数，并计算出它们之和

import java.util.Scanner; public class demo37{          public static void main(String[] args) {                   int sum = 0 ;                   for(int a=1 ; a<=5 ; a++){                           Scanner scan = new Scanner(System.in);                           System.out.println("请输入整数");                           int x = scan.nextInt();                           sum += x;                   }System.out.println("总数为"+sum);              } }

练习3：输入两个整数，判断第1个整数是否为第2个整数的倍数

import java.util.Scanner; public class demo1{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入第1个整数");                   int a = scan.nextInt() ; System.out.println("请输入第2个整数");                   int b = scan.nextInt() ;                   if(a%b == 0) {                           System.out.println(a+"是"+b+"的倍数");                   }else{                           System.out.println(a+"不是"+b+"的倍数");                    }          } }

练习4：编写一个程序，求整数n的阶乘，例如于的阶乘是1*2*3*4*5

import java.util.Scanner; public class demo4{ public static void main(String[] args) {          Scanner scan = new Scanner(System.in);          System.out.println("请输入整数");          int n = scan.nextInt() ;          int jc = 1;          for (int i=1; i<=n; i++) {                   jc *= i;          }System.out.println("n的阶乘为："+jc); }       }

练习5：输入三个整数x，y，z，请把这三个数由小到大输出

import java.util.Scanner; public class demo4{ public static void main(String[] args) {          Scanner scan = new Scanner(System.in);          System.out.println("请输入3个整数");          int x = scan.nextInt() ;          int y = scan.nextInt() ;          int z = scan.nextInt() ;          if(x>y || y>z) {                   System.out.println(z+"，"+y+"，"+x);          }else if(z>y || y>x) {                   System.out.println(x+"，"+y+"，"+z);          }else if(z>x || x>y) {                   System.out.println(y+"，"+x+"，"+z);          }else if(y>x || x>z) {                   System.out.println(z+"，"+x+"，"+y);          }else if(x>z || z>y) {                   System.out.println(y+"，"+z+"，"+x);          }else{                   System.out.println(x+"，"+z+"，"+y);          } } }

练习6：有一个不多于5位的正整数，求它是几位数，分别打印出每一位数字。

import java.util.Scanner; public class demo4{ public static void main(String[] args) {          Scanner scan = new Scanner(System.in);          System.out.println("请输入1个不多于5位的正整数");          int x = scan.nextInt() ;          if(x>=100000) {                   System.out.println("您的输入有误");          }else{          String y = String.valueOf(x);          int z = y.length();          System.out.println("您输入的数为"+z+"位数");          switch(z){                   case 1:                           System.out.println("每一个数分别为"+x);                           break;                   case 2:                           System.out.println("每一个数分别为"+x/10+"，"+x%10);                           break;                   case 3:                           System.out.println("每一个数分别为"+x/100+"，"+(x%100)/10+"，"+x%10);                           break;                   case 4:                           System.out.println("每一个数分别为"+x/1000+"，" + (x%1000)/100+"，"+(x%100)/10+"，"+x%10);                           break;                   default:                           System.out.println("每一个数分别为"+x/10000+"，"+(x%10000)/1000                           +"，"+(x%1000)/100+"，"+(x%100)/10+"，"+x%10);                   }          } } }

练习7：假设某员工今年的年薪是30000元，年薪的年增长率6%。编写一个Java应用程序计算该员工10年后的年薪，并统计未来10年（从今年算起）总收入。

public class demo4{ public static void main(String[] args) {          int sal = 30000 ;          int sum = 0;                      for(int i=1;i<=10;i++){                             sal =(int) (sal*(1+0.06)) ;                             sum += sal;                } System.out.println("10年后的年薪为"+sal+"元\t10年总工资为"+sum+"元"); } }

练习8：猴子第一天摘下若干个桃子，当即吃了一半，还不瘾，又多吃了一个，第二天早上又将剩下的桃子吃掉一半，又多吃了一个。以后每天早上都吃了前一天剩下的一半零一个。到第10天早上想再吃时，见只剩下一个桃子了。求第一天共摘了多少。

public class demo4{ public static void main(String[] args) {          int a = 1;                  for(int i=2; i<=10; i++) {                             a = (a+1)*2;                  } System.out.println("猴子第一天摘了 " + a + " 个桃子");   } }

练习9：由命令行输入一个4位整数，求将该数反转以后的数，如原数为1234，反转后的数位4321

import java.util.Scanner; public class demo4{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入1个4位整数");                   int x = scan.nextInt() ;                   if(x>=10000 || x<1000){                           System.out.println("您的输入有误");                   }else{                           int q = x/1000 ;                           int b = (x%1000)/100 ;                           int s = (x%100)/10 ;                           int g = x%10 ;                           System.out.println("原数为："+x+"\t反转后为："+g+s+b+q);                   }          }       }

练习10：求循环式子2+22+222+2222+22222的和，若第?个式子为p，则后一个式子p=p*10+2

public class demo1{          public static void main(String[] args) {                   int p = 0 ;                   int sum = 0 ;                   for(int i=1;i<=5;i++) {                           p = p*10 + 2 ;                           sum = sum + p ;                   }System.out.println(p+"\t和为"+sum);           } }

练习11：在一个图书系统的推荐图书列表中保存了50条信息，现在需要让它每行显示10条，分5行显示，请使用do…while实现

public class demo1{          public static void main(String[] args) {                   int b = 1 ;                   do{                           int a = 1 ;                           do{                                    System.out.print("这是第"+b+"行的第"+a+"条信息 ");                                    a++ ;                           }while(a<=10);                           b++ ;                           System.out.println();                   }while(b<=5);          } }

int a = 0;          do{                   a++;                   if((a-1)%10==0){                           System.out.println();                   }System.out.print("这是第"+a+"条信息,");          }while(a<50);

int a = 1;          do{                   System.out.print("这是第"+a+"条信息 ");                   if(a%10==0){                           System.out.println();                   }a++;          }while(a<=50);

练习12：学生输入6门成绩，若录入的成绩为负则跳出循环；若录入了6门合法成绩，则就算总成绩。

import java.util.Scanner; public class demo1{          public static void main(String[] args) {                   int sum = 0;                   for(int a=1;a<=6;a++){                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入每月销量");                   int x = scan.nextInt() ;                   sum += x ;                   }System.out.println("总销量为"+sum);           } }    //没实现跳出循环，不计算总成绩

import java.util.Scanner; public class demo1{          public static void main(String[] args) {                   int sum = 0;                   boolean flag = true ;                   for(int a=1;a<=6;a++){                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入第"+a+"门课程成绩");                   int x = scan.nextInt() ;                   if(x<0){                           flag = false ;                           break;                   }sum += x ;                   }if(flag){                           System.out.println("总成绩为"+sum);                   }else{                           System.out.println("输入成绩不合法，退出");                   }          } }

练习13：九九乘法表

public class demo20{          public static void main(String[] args) {                   System.out.println("java九九乘法表");                   for(int a=1;a<=9;a++){       //代表行数                           for(int b=1;b<=a;b++){   //代表每行的个数                                    System.out.print(a+"*"+b+"="+(a*b)+"  ");                           }System.out.println();                   }          } }

练习14：*型三角形的各种形式

public class demo21{          public static void main(String[] args) {                   System.out.println("java杨辉正直角三角形");                   for(int a=1;a<=9;a++){       //代表行数                           for(int b=1;b<=a;b++){   //代表每行的个数                                    System.out.print("*");                           }System.out.println();   //每执行完一行，换行                   }          } }

System.out.println("java杨辉正直角三角形");                   for(int a=1;a<=9;a++){       //代表行数                           for(int b=1;b<=a;b++){   //代表每行的个数                                    System.out.print("*");                           }System.out.println();   //每执行完一行，换行

System.out.println("java杨辉倒直角三角形");                   for(int a=9;a>=1;a--){       //代表行数                           for(int b=a;b>=1;b--){   //代表每行的个数                                    System.out.print("*");                           }System.out.println();   //每执行完一行，换行

System.out.println("java杨辉正等腰三角形");                   for(int a=1;a<=9;a++){       //代表行数                           for(int b=9;b>=a;b--){   //代表每行的空格个数                                    System.out.print(" ");                           }for(int c=1;c<2*a;c++){   //代表每行的*个数，首行1个*，下一行比上一行多2个*                                    System.out.print("*");                           }System.out.println();   //每执行完一行，换行

System.out.println("java杨辉倒等腰三角形");                   for(int a=9;a>=1;a--){       //代表行数                           for(int b=9;b>=a;b--){   //代表每行的空格个数                                    System.out.print(" ");                           }for(int c=2*a;c>1;c--){   //代表每行的*个数                                    System.out.print("*");                           }System.out.println();   //每执行完一行，换行

System.out.println("java杨辉正等腰三角形");                   for(int a=1;a<=9;a++){       //代表行数                           for(int b=9;b>=a;b--){   //代表每行的空格个数                                    System.out.print(" ");                           }for(int c=1;c<=a;c++){                                    System.out.print("*");                                    System.out.print(" ");                           }System.out.println();   //每执行完一行，换行

System.out.println("java杨辉倒等腰三角形");                   for(int a=9;a>=1;a--){       //代表行数                           for(int b=9;b>=a;b--){   //代表每行的空格个数                                    System.out.print(" ");                           }for(int c=a;c>=1;c--){   //代表每行的*个数                                    System.out.print("*");                                    System.out.print(" ");                           }System.out.println();   //每执行完一行，换行

练习15：java小计算器

import java.util.Scanner; public class demo5{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   System.out.println("请输入第一个数字");                   double a = scan.nextDouble() ;                   System.out.println("请输入运算符");                   String x = scan.next() ;                   System.out.println("请输入第2个数字");                   double b = scan.nextDouble() ;                   switch(x){                   case "+":                           System.out.println(a+x+b+"的结果为"+(a+b));                           break ;                   case "-":                           System.out.println(a+x+b+"的结果为"+(a-b));                           break ;                   case "*":                           System.out.println(a+x+b+"的结果为"+(a*b));                           break ;                   case "/":                           if(b!=0){                                    System.out.println(a+x+b+"的结果为"+(a/b));                                    break ;                           }else{                                    System.out.println("分母不能为0");                                    break ;                           }                   case "%":                           System.out.println(a+x+b+"的结果为"+(a%b));                           break ;                   default:                           System.out.println("不支持此运算");                   }          } }

 

练习16：收银台结账，如果购买商品数量≥10，且金额≥1000，就给他打九折，最后计算出他的应付金额

import java.util.Scanner; public class demo6{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   int num = 0 ;   //表示数量                   double sum = 0 ;   //表示总金额                   double money = 0 ;  //每次输入的金额                   System.out.println("请输入第1件物品金额");                   money = scan.nextDouble() ;                   while(money!=0){     //输入金额为0时，跳出循环，代表收银台扫码标签完成，没有货物需要结账了                           num++ ;                           sum += money ;                           System.out.println("请输入第"+(num+1)+"件物品金额");                           money = scan.nextDouble() ;                   }                   if(num>=10 && sum>=1000){                           sum = sum*0.9 ;                   }System.out.println("应付金额为"+sum);          } }  //while循环前，需要录入一个金额money，才可进入循环 //while循环前录入的金额，会进入总金额；while前的第一次输入，也会算进去，因为最后一次始终会输入0。

练习17：常用图形面积计算器

import java.util.Scanner; public class demo8{          public static void main(String[] args) {                   Scanner scan = new Scanner(System.in);                   double s = 1 ;                   System.out.println("请输入图形形状");                   String tx = scan.next() ;                   switch(tx){                   case "长方形":                           System.out.println("请输入长方形的长度为多少厘米");                           double c = scan.nextDouble() ;                           System.out.println("请输入长方形的宽度度为多少厘米");                            double k = scan.nextDouble() ;                           s = c*k ;                           System.out.println("长方形面积为"+s+"平方厘米");                           break ;                   case "圆形":                           System.out.println("请输入圆形的半径为多少厘米");                           double r = scan.nextDouble() ;                           s = 3.14*r*r ;                           System.out.println("圆形面积为"+s+"平方厘米");                           break ;                   case "三角形":                           System.out.println("请输入三角形的底为多少厘米");                           double d = scan.nextDouble() ;                           System.out.println("请输入三角形的高为多少厘米");                           double h = scan.nextDouble() ;                           s = d*h*0.5 ;                           System.out.println("三角形面积为"+s+"平方厘米");                           break ;                   default:                           System.out.println("对不起，不支持此图形");                   }          } }

作者：kerwin-chyl

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