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8. 写一个程序,输出类似09:03:12的时间格式,需要判断输入的数字是否符合实际情况,比如小时数就不能大于24,如果大于24就提示输入错误;分钟数和秒数不能大于60,如果大于60就提示输入错误。
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo18 {
- public static void main(String[] args){
-
- Scanner sc = new Scanner(System.in);
- System.out.println("请输入小时:");
- int hours = sc.nextInt();
- System.out.println("请输入分钟:");
- int minute = sc.nextInt();
- System.out.println("请输入秒:");
- int second = sc.nextInt();
-
- if(hours>24 & minute>60 & second>60) {
- System.out.println("输入非法");
- }else {
- if(hours/10%10<=0 & minute/10%10<=0 & second/10%10<=0){
-
- System.out.println("0"+hours+":"+"0"+minute+":"+"0"+second);
-
- }else if(hours/10%10>0 & minute/10%10<=0 & second/10%10<=0){
-
- System.out.println(hours+":"+"0"+minute+":"+"0"+second);
-
- }else if(hours/10%10<=0 & minute/10%10>0 & second/10%10<=0){
-
- System.out.println("0"+hours+":"+minute+":"+"0"+second);
-
- }else if(hours/10%10<=0 & minute/10%10<=0 & second/10%10>0){
-
- System.out.println("0"+hours+":"+"0"+minute+":"+second);
-
- }else if(hours/10%10>0 & minute/10%10<=0 & second/10%10>0){
-
- System.out.println(hours+":"+"0"+minute+":"+second);
-
- }else if(hours/10%10<=0 & minute/10%10>0 & second/10%10>0){
-
- System.out.println("0"+hours+":"+minute+":"+second);
-
- }else{
- System.out.println(hours+":"+minute+":"+"0"+second);
- }
-
-
- }
-
- }
- }
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9.使用if选择结构判断一个整数,属于哪个范围:大于0;小于0;
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo15 {
- public static void main(String[] args){
- Scanner sc= new Scanner(System.in);
- System.out.println("请输入一个整数:");
- int shu = sc.nextInt();
-
- if(shu>0){
- System.out.println("大于0");
- }else if(shu==0){
- System.out.println("等于0");
- }else{
- System.out.println("小于0");
- }
- }
- }
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10: 有3个整数,给出提示信息:
能否创建三角形;
如果能构建三角形,提示是直角三角形还是等边三角形等腰三角形还是普通三角形;
最后输出三角形面积;
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
- import java.util.*;
-
- public class Demo17 {
- public static void main(String[] args){
- Scanner sc = new Scanner(System.in);
- System.out.println("边长a:");
- double a = sc.nextDouble();
- System.out.println("边长b:");
- double b = sc.nextDouble();
- System.out.println("边长c:");
- double c = sc.nextDouble();
- System.out.println("能否构造三角形?");
-
- if(a+b>c && a+c>b && c+b>a){
- System.out.println("可以构造三角形");
- }
- double q =(a+b+c)/2;
- if (a*a==b*b+c*c || b*b==a*a+c*c || c*c== a*a+b*b) {
- System.out.println( "直角三角形");
- double s = Math.sqrt(q*(q-a)*(q-b)*(q-c));
- System.out.println("面积为:"+s);
-
- }else if(a==b & a==c & c==b){
- System.out.println("等腰三角形");
- double s1 = Math.sqrt(q*(q-a)*(q-b)*(q-c));
- System.out.println("面积为:"+s1);
-
- }else if(a==b | b==c){
- double s2 = Math.sqrt(q*(q-a)*(q-b)*(q-c));
- System.out.println("等边三角形"+s2);
-
- }else{
- double s3 = Math.sqrt(q*(q-a)*(q-b)*(q-c));
- System.out.println("普通三角形"+s3);
-
- }
-
- }
- }
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11:随机输入一个字母,如果是大写字母就转化为小写字母输出;如果是小写字母就转化为大写字母输出。
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
- public class Demo09 {
- public static void main(String[] args){
- Scanner sc= new Scanner(System.in);
- System.out.println("请输入字符:");
- String s = sc.next();
- String str="";
- char[] arr =s.toCharArray();
- for(int i=0;i<arr.length;i++){
- char c=arr[i];
- if(c>'a'&&c<'z'){
- char c1 = (char)(c-32);
- str += c1;
- }else if(c>'A'&&c<'Z'){
- char c2= (char)(c+32);
- str += c2;
- }else{
- str += c;
- }
- }
- System.out.println("大小写转换结果:"+ str);
-
- }
-
- }
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12:使用if结构实现学习成绩>=90分的同学用A表示,60-89分之间的用B表示,60分以下的用C表示。
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo10 {
- public static void main(String[] args){
- Scanner sc= new Scanner(System.in);
- System.out.println("请输入学生成绩:");
- int score = sc.nextInt();
- if(score>=90){
- System.out.println("A");
- }else if(score>60 & score<89){
- System.out.println("B");
- }else{
- System.out.println("C");
- }
- }
-
- }
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13:使用条件结构实现:岳灵珊同学参加到Java的学习,他父亲岳不群和母亲宁中则承诺:
如果岳灵珊的考试成绩==1OO分,父亲给她买辆车
如果岳灵珊的考试成绩>=90分,母亲给她买台笔记本电脑
如果岳灵珊的考试成绩>=60分,母亲给她买部手机
如果岳灵珊的考试成绩<60分,没有礼物
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo11 {
- public static void main(String[] arge){
- Scanner sc =new Scanner(System.in);
- System.out.println("岳灵珊的考试成绩:");
- int score = sc.nextInt();
-
- if(score==100){
- System.out.println("父亲给她买一辆车");
- }else if(score>=90){
- System.out.println("母亲给她买台笔记本电脑");
- }else if(score>=60){
- System.out.println("母亲给她买部手机");
- }else{
- System.out.println("没礼物");
- }
- }
- }
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14:使用条件结构实现,如果用户名等于字符‘青’,密码等于数字‘123’,就输出“欢迎你,青”,否则就输出“对不起,你不是青”。
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo12 {
- public static void main(String[] arge){
- Scanner sc = new Scanner(System.in);
- System.out.println("请输入用户名:");
- String name = sc.next();
- System.out.println("请输入密码");
- String code = sc.next();
-
- if(name.equals("青") & code.equals("123")){
- System.out.println("欢迎你,青");
- }else{
- System.out.println("对不起,你不是青");
- }
- }
- }
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15:求ax2+bx+c=0方程的根。
a,b,c分别为函数的参数,
如果:b2-4ac>0,则有两个解;b2-4ac=0,则有一个解;b2-4ac<0,则无解;
已知:
x1=(-b+sqrt(b2-4ac))/2a
x2=(-b-sqrt(b2-4ac))/2a
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo16 {
- public static void main(String[] args){
- Scanner sc = new Scanner(System.in);
- System.out.println("请输入二次方系数a:");
- double a = sc.nextDouble();
- System.out.println("请输入一次方系数b:");
- double b = sc.nextDouble();
- System.out.println("请输入常数c:");
- double c = sc.nextDouble();
- double t=b*b-4*a*c;
-
- if(a==0){
-
- System.out.println("二次方程系数a不能为0!");
-
- }else if(t>0){
-
- double x1 = (-b+t)/(2*a);
- double x2 = (-b-t)/(2*a);
- System.out.println("x1="+x1+",x2="+x2);
-
- }else if(t==0){
-
- double x1 = (-b+t)/(2*a);
- System.out.println("解为x2=x1="+x1);
-
- }else{
-
- System.out.println("无解!");
-
- }
- }
- }
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16:使用switch选择结构实现判断某年某月某日是这一年的第几天?
- package cn.bdqn.demo03;
-
- import java.util.Scanner;
-
- public class Demo14 {
- public static void main(String[] args){
- Scanner sc = new Scanner(System.in);
- System.out.println("输入年份:");
- int year =sc.nextInt();
- System.out.println("输入月份:");
- int month =sc.nextInt();
-
- if( year % 4 ==0 && year % 100 !=0 || year % 400 == 0){
- switch (month){
- case 1:
- case 3:
- case 5:
- case 7:
- case 8:
- case 10:
- case 12:
- System.out.println(month+"月是31天!");
- break;
- case 2:
- System.out.println(month+"月是闰年为29天");
- break;
- case 4:
- case 6:
- case 9:
- case 11:
- System.out.println(month +"月是30天!");
- break;
- default:
- System.out.println("数据有误!");
- }
- }else{
- switch (month){
- case 1:
- case 3:
- case 5:
- case 7:
- case 8:
- case 10:
- case 12:
- System.out.println(month+"月是31天!");
- break;
- case 2:
- System.out.println(month+"月不是闰年为28天");
- break;
- case 4:
- case 6:
- case 9:
- case 11:
- System.out.println(month +"月是30天!");
- break;
- default:
- System.out.println("数据有误!");
- }
- }
- }
- }
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17:使用switch选择结构判断一个月份属于一年中的那个季节。(春夏秋冬)
- package cn.bdqn.demo03;
-
- public class Demo13 {
- public static void main(String[] args){
- // case穿透现象的使用
- /*
- * 输入月份,输出季节
- * 12 1 2 冬季 3 4 5 春季 6 7 8 夏季 9 10 11 秋季
- */
-
- int month = 6;
-
- switch (month) {
- case 12:
- case 1:
- case 2:
- System.out.println("冬季");
- break;
- case 3:
- case 4:
- case 5:
- System.out.println("春季");
- break;
- case 6:
- case 7:
- case 8:
- System.out.println("夏季");
- break;
- case 9:
- case 10:
- case 11:
- System.out.println("秋季");
- break;
- }
- }
- }
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