《JAVA基础教程》第三章 Java程序设计基础

实验10import java.util.*;public class shiyan10{public static void main(String[] args){int a=0,b=0,c=0,max=0;Scanner reader=new Scanner(System.in);System.out.println("从键盘输入第一个整数");a=reader.nextInt();System.out.println("从键盘输入第二个整数");b=reader.nextInt();System.out.println("从键盘输入第三个整数");c=reader.nextInt();if(a>b)max=a;elsemax=b;if(c>max)max=c;System.out.println("最大的数是"+max);}}//在程序中输入三个整数，比较它们的大小，输出最大的数实验11public class shiyan11{public static void main(String[] args){int s=0;for(int i=0;i<100;i++){s=s+i;i++;}System.out.println("1+3+5+···+99="+s);}}//用for循环语句求1+3+5+···+99的值实验12import java.util.*;public class shiyan12{public static void main(String[] args){int a=0,i=1,s=0;Scanner reader=new Scanner(System.in);while(a<50||a>100){System.out.println("从键盘输入一个50~100的整数");a=reader.nextInt();}System.out.println("你输入的数是"+a);while(i<=a){s=s+i;i++;}System.out.println("1+2+3+···+"+a+"="+s);}}//编写从键盘输入一个范围在50~100的整数，如果不正确，则继续输入；然后求1到输入整数的累加实验13public class shiyan13{public static void main(String[]args){int i=100,s=0;do{s=s+i;i--;}while(i>0);System.out.println("100+99+98+···+2+1="+s);}}//用do-while语句求100+99+···+2+1的值实验14import java.util.*;public class shiyan14{public static void main(String[] args)int a=-1;Scanner reader=new Scanner(System.in);System.out.println("从键盘输入0~6的整数");a=reader.nextInt();while(a<0||a>6){System.out.println("输入错误");System.out.println("从键盘输入0~6的整数");a=reader.nextInt();}switch(a){case 0:System.out.println("今天是星期日");break;case 1:System.out.println("今天是星期一");break;case 2:System.out.println("今天是星期二");break;case 3:System.out.println("今天是星期三");break;case 4:System.out.println("今天是星期四");break;case 5:System.out.println("今天是星期五");break;case 6:System.out.println("今天是星期六");break;default:System.out.println("输入错误");break;}}}//让用户通过输入一个0~6的整数，显示今天是xingqijipublic class shiyan15{public static void main(String[] args){for(int i=1;i<10;i++){if(i==6)break;System.out.println(""+i);}System.out.println("\n显示完毕");for(int i=1;i<10;i++){if(i%2==0)continue;System.out.println(""+i);}System.out.println("\n显示完毕");}}//先显示1~5各个整数，然后再显示1~10的各个奇数。

Java程序设计基础习题答案Ｊavａ程序设计基础课后习题参考答案第2章1、关于Jａｖa Applicａｔion得入口方法maｉn（）得检验:ｍａin（）方法得参数名就是否可以改变?maｉｎ（）方法得参数个数就是否可以改变？该方法名就是否可以改变？参考答案:（1)maｉn（）方法得参数名可以改变.(2）maiｎ()方法得参数个数不可以改变。

（3）该方法名不可以改变。

2、当一个程序没有main（)方法时，能编译吗?如果能编译，能运行吗?参考答案:当一个程序没有ｍaｉn(）方法就是，就是可以编译通过得,但就是不能给运行,因为找不到一个主函数入口。

3、下列语句能否编译通过？bytｅi =127；ｂｙｔｅj = １28；longｌ1 = ９99９９９；ｌoｎg l２= ９9９9999999；参考答案：ｂyｔe i 与long l１可以编译通过。

而bｙte j 与ｌongｌ2 超出自身数据类型范围,所以编译失败。

4、下列语句能否编译通过？float f1 =3、５；floａt f2 = 3.5f;参考答案：java中浮点型得数据在不声明得情况下都就是doubl ｅ型得，如果要表示一个数据就是ｆloaｔ型得,必须在数据后面加上“Ｆ”或“ｆ”；因此,floatｆ1 无法编译通过。

5、验证ｉnt 与char，ｉnt与doｕbｌｅ等类型就是否可以相互转换。

参考答案:(１）cｈar类型可以转换为iｎt 类型得，但就是inｔ类型无法转换为chａｒ类型得;（２）iｎt 可以转换为ｄoubｌe类型得，但就是ｄｏuble类型无法转换为int 类型得。

6、计算下列表达式,注意观察运算符优先级规则。

若有表达式就是非法表达式,则指出不合法之处且进行解释。

（1)4+5 ＝= 6＊2 ?（2) （4=5）/6??(3）９%2*7/3＞17（4）(4＋5）<=6/3 ?(5) 4＋5％３！=7－2（６）４+5/6〉=10％2参考答案：表达式（２）为不合法表达式，只能将值赋值给一个变量,因此其中（4=5）将5赋值给4就是不合法得.7、下列（）就是合法得Ｊava标识符。

java程序设计基础第三版Java程序设计基础第三版Java是一种广泛使用的编程语言，以其跨平台的特性、面向对象的特性、健壮性、安全性和性能而闻名。

《Java程序设计基础》第三版是对Java语言的深入介绍，适合初学者和有一定编程基础的读者。

本版书籍在前两版的基础上，更新了Java语言的最新发展，并增加了一些实用的编程技巧。

第一章：Java语言概述Java语言由Sun Microsystems公司（现为Oracle公司）在1995年发布。

Java是一种纯面向对象的语言，这意味着在Java中，所有的数据都是对象。

Java的设计哲学是“一次编写，到处运行”（Write Once, Run Anywhere），这得益于它的虚拟机（JVM）技术。

第二章：Java开发环境搭建在开始Java编程之前，需要安装Java开发工具包（JDK），并配置环境变量。

此外，还可以使用集成开发环境（IDE）如Eclipse或IntelliJ IDEA来提高开发效率。

第三章：基本语法Java的基本语法包括数据类型、变量、运算符、控制语句等。

Java是强类型语言，所有变量在使用前必须声明其类型。

Java提供了丰富的控制语句，如if-else、switch、while、for等。

第四章：面向对象编程面向对象编程（OOP）是Java的核心特性。

本章介绍了类和对象的概念，以及如何使用类来封装数据和行为。

此外，还介绍了继承、多态和接口等OOP的基本概念。

第五章：数组和字符串数组是Java中存储固定大小的同类型元素的集合。

字符串是字符的序列，Java提供了String类来处理字符串，包括字符串的创建、连接、比较等操作。

第六章：集合框架Java集合框架提供了一套接口和类，用于存储和操作对象集合。

包括List、Set、Map等接口，以及ArrayList、HashSet、HashMap等实现类。

第七章：异常处理Java使用异常处理机制来处理程序运行时出现的错误。

java程序设计基础课后习题答案Java程序设计基础课后习题答案在学习Java程序设计基础课程的过程中，课后习题是非常重要的一部分。

通过完成课后习题，我们可以巩固课堂上所学的知识，提高编程能力，加深对Java 语言的理解。

下面我们来看一些常见的Java程序设计基础课后习题答案。

1. 编写一个Java程序，实现输入两个整数，然后输出它们的和。

```javaimport java.util.Scanner;public class AddTwoNumbers {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.println("请输入第一个整数：");int num1 = input.nextInt();System.out.println("请输入第二个整数：");int num2 = input.nextInt();int sum = num1 + num2;System.out.println("它们的和是：" + sum);}}```2. 编写一个Java程序，实现输入一个整数，然后判断它是奇数还是偶数。

```javaimport java.util.Scanner;public class OddOrEven {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.println("请输入一个整数：");int num = input.nextInt();if (num % 2 == 0) {System.out.println(num + "是偶数");} else {System.out.println(num + "是奇数");}}}```3. 编写一个Java程序，实现输入一个年份，然后判断它是否是闰年。

《Java语言程序设计-基础篇》第03章答案3.1 答：if(i % 2 == 0) System.out.println(“偶数”); else System.out.println(“奇数”); 3.2 答：当 x = 3, y = 2 时，输出：无输出当x = 3, y = 4 时，输出：z is 7 当 x = 2，y = 2 时，输出：x is 2 3.3 答：等价的语句有：a, c和d 正确缩进的是：c 3.4 答：当 x = 2, y = 3 时，输出：x is 2 当 x = 3, y = 2 时，输出：无输出当 x = 3，y = 3 时，输出：z is 7 3.5 答：等价 3.6 答：switch变量可以是char, byte, short, int。

执行case语句后没有break，则继续执行下一个case语句。

switch可转换为等价的if语句（嵌套），反之不一定可以。

3.7 答：y的值是2。

3.8 答：switch(a){ case 1: x += 5; break; case 2: x += 10; break; case 3: x += 16; break; case 4: x += 34; } 3.9 答：System.out.print(count + (count % 10 == 0 ? “＼n“ : ““)); 3.10 答：（a）执行0次，无输出（b）执行9次，输出如下：3 5 7 9 3.11 答：（略）3.12 答：相同，均为45。

3.13 答：for(int i = 1; i System.out.println(i); 3.14 答：无限循环。

3.15 答：不能。

3.16 答：能。

（略）3.17 答：（略）3.18 答：（a）输出：balance is 1 （b）不能结束（编译有错，输出语句执行不到）3.19 答：能。

（略）3.20 答：int i=0; while(iif(i%3==0){ i++; continue; } sum += i; i++; } 3.21 答：（a）主方法如下：public static void main(String[] args) { int sum = 0; int number = 0; while(number number++; sum += number; } System.out.println(“The number is “ + number); System.out.println(“The sum is “ + sum); } （b）主方法如下：public static void main(String[] args) { int sum = 0; int number = 0; while(number number++; if(!(number == 10 || number == 11)) sum += number; } System.out.println(“The number is “ + number); System.out.println(“Thesum is “ + sum); } 3.22 答：执行next:后面的语句。

《程序设计基础（Java）》教案一、教学目标1. 让学生掌握Java编程语言的基本语法和结构。

2. 培养学生编写简单的Java程序，为后续深入学习打下基础。

3. 帮助学生理解面向对象编程的基本概念，如类、对象、封装、继承和多态。

二、教学内容1. Java语言简介：介绍Java语言的发展历程、特点和应用领域。

2. Java基本语法：变量、数据类型、运算符、控制语句、数组和字符串。

3. 面向对象编程：类与对象、封装、继承和多态。

4. 常用Java类库：ng、java.util、java.awt等。

5. 编程实践：编写简单的Java程序，如计算器、排序算法等。

三、教学方法1. 讲授法：讲解Java语言的基本语法和面向对象编程概念。

2. 案例分析法：分析实际编程案例，让学生理解面向对象编程的应用。

3. 实践操作法：让学生动手编写Java程序，提高编程能力。

4. 讨论法：分组讨论编程问题，培养学生的团队协作能力。

四、教学安排1. 第1-2课时：Java语言简介及基本语法。

2. 第3-4课时：面向对象编程。

3. 第5-6课时：常用Java类库。

4. 第7-8课时：编程实践。

5. 第9-10课时：总结与复习。

五、教学评价1. 课堂参与度：评估学生在课堂上的发言和提问情况。

2. 编程作业：评估学生编写的Java程序的正确性和完整性。

3. 小组讨论：评估学生在讨论中的表现和团队协作能力。

4. 期末考试：考察学生对Java编程基础知识的掌握程度。

六、教学资源1. 教材：《Java程序设计基础》2. 课件：教师自制的PPT课件3. 编程环境：Eclipse、IntelliJ IDEA等4. 在线编程平台：LeetCode、牛客网等5. 教学视频：网易云课堂、慕课网等提供的Java编程教程七、教学过程1. 导入：通过介绍Java语言在实际应用中的案例，激发学生的学习兴趣。

2. 讲解：结合课件，讲解Java语言的基本语法和面向对象编程概念。

java程序设计基础知识⼀、Java语⾔概述1.1 Java基本概念:类是java程序的基本构成单位，重要的⼊⼝main⽅法,基本结构主类主⽅法public class test{public static void main(String[] args){System.println(“hello java”);}}1.2 Java特性：跨平台、安全稳定、⽀持多线程、⽀持⽹络编程、具有丰富的库函数、⾯向对象(继承、封装、多态)1.3 Java程序的执⾏环境和源⽂件处理过程：javac xxx.java //编译java xxx //运⾏举个栗⼦：假设有⼀个test.java⽂件javac test.javajavac test编译如果通过就会⽣成⼀个.class后缀结尾的字节码(bytecode)⽂件字节码由Java虚拟机执⾏1.4 JDK⽂件的结构：bin: 该⽬录存放运⾏程序；db: 该⽬录存放有关数据库⽅⾯的⽂件；demo: 该⽬录存放⼀些实例⽂件；include: 该⽬录存放与C相关的头⽂件；jre：该⽬录存放java运⾏环境相关的⽂件；lib: 该⽬录存放程序库；更多的可以了解JDK官⽅⽂档查就ok1.5 ⾯向对象的软件开发过程：⾯向对象的分析(Object Oriented Analysis OOA)⾯向对象的设计(Object Oriented Design OOD)⾯向对象的实现(Object Oriented Programming OOP)⼆、Java编程基础2.1 基础数据类型：注意和包装类的区别（包装类⾸字母⼤写，⽽基本类型都是⼩写），注意和C语⾔的区别，注意类型之间的转换，低精度可以直接存储到⾼精度变量中，这是⾃动转换；⾼精度数据放⼊低精度变量必须强制转换。

还要注意有些数据类型不能转换。

⽐如boolean不能将其转换为其他类型，尤其是整型，这⼀点是和C的明显区别。

float a=8.1; //报错，8.1默认是double类型2.2 命名规则：类、接⼝⾸字母⼤写，变量⾸字母⼩写，常量全⼤写（⾏业惯例）标识符的命名规则（掌握，这是强⾏规定）⾸字符必须是字母（⼤⼩写均可）、下划线(_)或美元符号（$）标识符可以由数字（0-9）、A-Z、a-z和下划线(_)、美元符号（$）长度不限2.3 Java的注释符号a) 单⾏注释//开始⾏尾结束b) 多⾏注释/*开始 */结束c) doc注释/**开始 */结束注意：第3种注释主要是为⽀持JDK⼯具javadoc⽽采⽤的。

《Java语言程序设计（基础篇）》（第10版梁勇著）第三章练习题答案《Java语言程序设计（基础篇）》（第10版梁勇著）第三章练习题答案3.1public class Exercise03_01 {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.print("Enter a, b, c: ");double a = input.nextDouble();double b = input.nextDouble();double c = input.nextDouble();double discriminant = b * b - 4 * a * c;if (discriminant < 0) {System.out.println("The equation has no real roots");}else if (discriminant == 0) {double r1 = -b / (2 * a);System.out.println("The equation has one root " + r1);}else { // (discriminant > 0)double r1 = (-b + Math.pow(discriminant, 0.5)) / (2 * a);double r2 = (-b - Math.pow(discriminant, 0.5)) / (2 * a);System.out.println("The equation has two roots " + r1 + " and " + r2);}}}3.1附加public class Exercise03_01Extra {public static void main(String args[]) {Scanner input = new Scanner(System.in);System.out.print("Enter a numerator: ");int numerator = input.nextInt();System.out.print("Enter a denominator: ");int denominator = input.nextInt();if (numerator < denominator) {System.out.println(numerator + " / " + denominator + " is a proper fraction");}else if (numerator % denominator == 0) {System.out.print(numerator + " / " + denominator + " is an improper fraction ");System.out.println("and it can be reduced to " + numerator / denominator);}else {System.out.print(numerator + " / " + denominator + " is an improper fraction ");System.out.println("and its mixed fraction is " + numerator / denominator + " + " +numerator % denominator + " / " + denominator);}}}3.2public class Exercise03_02 {public static void main(String[] args) {Scanner input = new Scanner(System.in);int number1 = (int)(System.currentTimeMillis() % 10);int number2 = (int)(System.currentTimeMillis() * 7 % 10);int number3 = (int)(System.currentTimeMillis() * 3 % 10);System.out.print("What is " + number1 + " + " + number2 + " + " +number3 + "? ");int answer = input.nextInt();System.out.println(number1 + " + " + number2 + " + " + number3 +" = " + answer + " is " +(number1 + number2 + number3 == answer));}}3.2附加public class Exercise03_02Extra {public static void main(String args[]) {Scanner input = new Scanner(System.in);System.out.print("Enter the coordinates for two points: ");double x1 = input.nextDouble();double y1 = input.nextDouble();double x2 = input.nextDouble();double y2 = input.nextDouble();double m = (y2 - y1) / (x2 - x1);double b = y1 - m * x1;System.out.print("The line equation for two points (" + x1 + ", " + y1 + ") and (" + x2 + ", " + y2 + ") is " + "y = ");if (m == -1)System.out.print("-x");else if (m == 1)System.out.print("x");elseSystem.out.print(m + "x");if (b > 0)System.out.println(" + " + b);else if (b < 0)System.out.println(" - " + (-1 * b));else// b is 0System.out.println();}}3.3public class Exercise03_03 {public static void main(String[] args) {Scanner input = new Scanner(System.in); System.out.print("Enter a, b, c, d, e, f: ");double a = input.nextDouble();double b = input.nextDouble();double c = input.nextDouble();double d = input.nextDouble();double e = input.nextDouble();double f = input.nextDouble();double detA = a * d - b * c;if (detA == 0) {System.out.println("The equation has no solution"); }else {double x = (e * d - b * f) / detA;double y = (a * f- e * c) / detA;System.out.println("x is " + x + " and y is " + y);}}}3.3附加public class Exercise03_03Extra {public static void main(String[] args) {final double RADIUS = 5;double angle = Math.random() * 2 * Math.PI;double x = RADIUS * Math.random() * Math.cos(angle);double y = RADIUS * Math.sin(angle);double distance = Math.pow(x * x + y * y, 0.5);System.out.println("The point is (" + x + ", " + y + ") and its distance to the center is " + distance);}}3.4public class Exercise03_04 {public static void main(String[] args) {int number = (int)(Math.random() * 12) + 1;// or int number = (int)(System.currentTimeMillis() % 12 + 1);// or int number = (int)(Math.random() * 12) + 1;if (number == 1)System.out.println("Month is Januaray");else if (number == 2)System.out.println("Month is Feburary");else if (number == 3)System.out.println("Month is March");else if (number == 4)System.out.println("Month is April");else if (number == 5)System.out.println("Month is May");else if (number == 6)System.out.println("Month is June");else if (number == 7)System.out.println("Month is July");else if (number == 8)System.out.println("Month is August");else if (number == 9)System.out.println("Month is September");else if (number == 10)System.out.println("Month is October");else if (number == 11)System.out.println("Month is November");else// if (number == 12)System.out.println("Month is December");}}3.5public class Exercise03_05 {public static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in);// Prompt the user to enter an integer for todaySystem.out.print("Enter today抯 day: ");int today = input.nextInt();System.out.print("Enter the number of days elapsed since today: ");int elapsedDays = input.nextInt();String nameForToday;if (today == 0)nameForToday = "Sunday";else if (today == 1)nameForToday = "Monday";else if (today == 2)nameForToday = "Tuesday";else if (today == 3)nameForToday = "Wednesday";else if (today == 4)nameForToday = "Thursday";else if (today == 5)nameForToday = "Friday";else// if (today == 6)nameForToday = "Saturday";int futureDay = (today + elapsedDays) % 7; String nameForFutureDay;if (futureDay == 0)nameForFutureDay = "Sunday";else if (futureDay == 1) nameForFutureDay = "Monday";else if (futureDay == 2) nameForFutureDay = "Tuesday";else if (futureDay == 3) nameForFutureDay = "Wednesday";else if (futureDay == 4) nameForFutureDay = "Thursday";else if (futureDay == 5) nameForFutureDay = "Friday";else// if (futureDay == 6) nameForFutureDay = "Saturday";System.out.println("Today is " + nameForToday+ " and the future day is " + nameForFutureDay); } }3.6public class Exercise03_06 {public static void main(String[] args) {Scanner input = new Scanner(System.in);// Prompt the user to enter weight in pounds System.out.print("Enter weight in pounds: "); double weight = input.nextDouble();// Prompt the user to enter heightSystem.out.print("Enter feet: ");double feet = input.nextDouble();System.out.print("Enter inches: ");double inches = input.nextDouble();double height = feet * 12 + inches;// Compute BMIdouble bmi = weight * 0.45359237 / ((height * 0.0254) * (height * 0.0254));// Display resultSystem.out.println("BMI is " + bmi);if (bmi < 18.5)System.out.println("Underweight");else if (bmi < 25)System.out.println("Normal");else if (bmi < 30)System.out.println("Overweight");elseSystem.out.println("Obese");}}3.7/** Break down an amount into smaller units* Display the non-zero denominations only, and display singular* words for single units like 1 dollars, 1 penny, and display plural * words for more than one unit like 2 dollars, 3 pennies.*/public class Exercise03_07 {// Main methodpublic static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in);// Receive the amount entered from the keyboardSystem.out.print("Enter an amount in double, for example 11.56: ");double amount = input.nextDouble();int remainingAmount = (int)(amount * 100);// Find the number of one dollarsint numberOfOneDollars = remainingAmount / 100;remainingAmount = remainingAmount % 100;// Find the number of quarters in the remaining amountint numberOfQuarters = remainingAmount / 25;remainingAmount = remainingAmount % 25;// Find the number of dimes in the remaining amountint numberOfDimes = remainingAmount / 10;remainingAmount = remainingAmount % 10;// Find the number of nickels in the remaining amountint numberOfNickels = remainingAmount / 5;remainingAmount = remainingAmount % 5;// Find the number of pennies in the remaining amountint numberOfPennies = remainingAmount;// Display resultsif (amount < 0) {System.out.println("Your amount is negative");System.exit(1);}else if (amount < 0) {System.out.println("Your amount is zero");System.exit(2);}System.out.println("Your amount " + amount + " consists of ");if (numberOfOneDollars > 1)System.out.println(numberOfOneDollars + "\ dollars");else if (numberOfOneDollars == 1)System.out.println(numberOfOneDollars + "\ dollar");if (numberOfQuarters > 1)System.out.println(numberOfQuarters + "\ quarters");else if (numberOfQuarters == 1)System.out.println(numberOfQuarters + "\ quarter");if (numberOfDimes > 1)System.out.println(numberOfDimes + "\ dimes");else if (numberOfDimes == 1)System.out.println(numberOfDimes + "\ dime");if (numberOfNickels > 1)System.out.println(numberOfNickels + "\ nickels");else if (numberOfNickels == 1)System.out.println(numberOfNickels + "\ nickel");if (numberOfPennies > 1)System.out.println(numberOfPennies + "\ pennies");else if (numberOfPennies == 1)System.out.println(numberOfPennies + "\ penny");}}3.8public class Exercise03_08 {public static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in); // Enter three numbersSystem.out.print("Enter three integers: ");int number1 = input.nextInt();int number2 = input.nextInt();int number3 = input.nextInt();if (number1 > number2) {int temp = number1;number1 = number2;number2 = temp;}if (number2 > number3) {int temp = number2;number2 = number3;number3 = temp;}if (number1 > number2) {int temp = number1;number1 = number2;number2 = temp;}System.out.println("The sorted numbers are "+ number1 + " " + number2 + " " + number3);}}public class Exercise03_09 {public static void main(String[] args) {Scanner input = new Scanner(System.in);// Prompt the user to enter an integerSystem.out.print("Enter the first 9 digits of an ISBN as integer: ");int number = input.nextInt();// Calculate checksum (You may write a loop to simplify it in Ch4int checksum =((number / 100000000 % 10) * 1 +(number / 10000000 % 10) * 2 +(number / 1000000 % 10) * 3 +(number / 100000 % 10) * 4 +(number / 10000 % 10) * 5 +(number / 1000 % 10) * 6 +(number / 100 % 10) * 7 +(number / 10 % 10) * 8 +(number % 10) * 9) % 11;System.out.print("The ISBN-10 number is ");// Display leading zeros, improve the solution using loops in the next chapterif (number / 100000000 == 0) {System.out.print("0");if (number / 10000000 == 0) {System.out.print("0");if (number / 1000000 == 0) {System.out.print("0");if (number / 100000 == 0) {System.out.print("0");if (number / 10000 == 0) { System.out.print("0");if (number / 1000 == 0) { System.out.print("0");if (number / 100 == 0) {System.out.print("0");if (number / 10 == 0) {System.out.print("0");if (number == 0) {System.out.print("0");}}}}}}}}}System.out.print(number);if (checksum == 10)System.out.print("X");elseSystem.out.print(checksum);}}3.10public class Exercise03_10 {public static void main(String[] args) {// 1. Generate two random single-digit integersint number1 = (int)(Math.random() * 10);int number2 = (int)(Math.random() * 10);// 2. Prompt the student to answer 搘hat is number1 + number2?? System.out.print("What is " + number1 + " + " + number2 + "? "); Scanner input = new Scanner(System.in);int answer = input.nextInt();// 4. Grade the answer and display the resultString replyString;if (number1 + number2 == answer)replyString = "You are correct!";elsereplyString = "Your answer is wrong.\" + number1 + " + "+ number2 + " should be " + (number1 + number2);System.out.println(replyString);}}3.11public class Exercise03_11 {public static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in);// Prompt the user to enter inputSystem.out.print("Enter a month in the year (e.g., 1 for Jan): ");int month = input.nextInt();System.out.print("Enter a year: ");int year = input.nextInt();int numberOfDaysInMonth = 0;switch (month) {case 1:System.out.print("January " + year);numberOfDaysInMonth = 31;break;case 2:System.out.print("February " + year);if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) { numberOfDaysInMonth = 29;}else {numberOfDaysInMonth = 28;}break;case 3:System.out.print("March " + year);numberOfDaysInMonth = 31;break;case 4:System.out.print("April " + year);numberOfDaysInMonth = 30;break;case 5:System.out.print("May " + year);numberOfDaysInMonth = 31;break;case 6:System.out.print("June " + year);numberOfDaysInMonth = 30;break;case 7:System.out.print("July " + year);numberOfDaysInMonth = 31;break;case 8:System.out.print("August " + year);numberOfDaysInMonth = 31;break;case 9:System.out.print("September " + year);numberOfDaysInMonth = 30;break;case 10:System.out.print("October " + year);numberOfDaysInMonth = 31;break;case 11:System.out.print("November " + year);numberOfDaysInMonth = 30;break;case 12:System.out.print("December " + year);numberOfDaysInMonth = 31;break;}System.out.print(" has " + numberOfDaysInMonth + " days"); }}3.12public class Exercise03_12 {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.print("Enter a three-digit integer: ");int number = input.nextInt();if (number / 100 == number % 10)System.out.println(number + " is a palindrome");elseSystem.out.println(number + " is not a palindrome");}}3.13public class Exercise03_13 {public static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in);// Prompt the user to enter filing statusSystem.out.print("(0-single filer, 1-married jointly or qualifying widow(er),"+ "\2-married separately, 3-head of household)\" + "Enter the filing status: ");int status = input.nextInt();// Prompt the user to enter taxable incomeSystem.out.print("Enter the taxable income: ");double income = input.nextDouble();// Compute taxdouble tax = 0;if (status == 0) { // Compute tax for single filersif (income <= 8350) {tax = income * 0.10;} else if (income <= 33950) {tax = 8350 * 0.10 + (income - 8350) * 0.15;} else if (income <= 82250) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (income - 33950)* 0.25; } else if (income <= 171550) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (income - 82250) * 0.28;} else if (income <= 372950) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (171550 - 82250) * 0.28 + (income - 171550) * 0.33;} else {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (82250 - 33950) * 0.25 + (171550 - 82250) * 0.28 + (372950 - 171550) * 0.33 + (income - 372950) * 0.35;}} else if (status == 1) { // Compute tax for married file jointly if (income <= 16700) {tax = income * 0.10;} else if (income <= 67900) {tax = 16700 * 0.10 + (income - 16700) * 0.15;} else if (income <= 137050) {tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (income - 67900) * 0.25; } else if (income <= 208850) {tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (income - 137050) * 0.28;} else if (income <= 372950) {tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (208850 - 137050) * 0.28 + (income - 208850) * 0.33;} else {tax = 16700 * 0.10 + (67900 - 16700) * 0.15 + (137050 - 67900) * 0.25 + (171950 - 137050) * 0.28 + (372950 - 208850) * 0.33+ (income - 372950) * 0.35;}} else if (status == 2) { // Compute tax for married separately if (income <= 8350) {tax = income * 0.10;} else if (income <= 33950) {tax = 8350 * 0.10 + (income - 8350) * 0.15;} else if (income <= 68525) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (income - 33950) * 0.25; } else if (income <= 104425) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (income - 68525) * 0.28;} else if (income <= 186475) {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (104425 - 68525) * 0.28 + (income - 104425) * 0.33;} else {tax = 8350 * 0.10 + (33950 - 8350) * 0.15 + (68525 - 33950) * 0.25 + (104425 - 68525) * 0.28 + (186475 - 104425) * 0.33 + (income - 186475) * 0.35;}} else if (status == 3) { // Compute tax for head of household if (income <= 11950) {tax = income * 0.10;} else if (income <= 45500) {tax = 11950 * 0.10 + (income - 11950) * 0.15;} else if (income <= 117450) {tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (income - 45500) * 0.25; } else if (income <= 190200) {tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (income - 117450) * 0.28;} else if (income <= 372950) {tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (190200 - 117450) * 0.28 + (income - 190200) * 0.33;} else {tax = 11950 * 0.10 + (45500 - 11950) * 0.15 + (117450 - 45500) * 0.25 + (190200 - 117450) * 0.28 + (372950 - 190200) * 0.33+ (income - 372950) * 0.35;}} else {System.out.println("Error: Wrong filing status");System.exit(1);}// Display the resultSystem.out.println("Tax is " + (int) (tax * 100) / 100.0);}}3.14public class Exercise03_14 {public static void main(String[] args) {// Obtain the random number 0 or 1int number = (int)(Math.random() * 2);// Prompt the user to enter a guessjava.util.Scanner input = new java.util.Scanner(System.in);System.out.print("Guess head or tail? " +"Enter 0 for head and 1 for tail: ");int guess = input.nextInt();// Check the guessif (guess == number)System.out.println("Correct guess");else if (number == 0)System.out.println("Sorry, it is a head");elseSystem.out.println("Sorry, it is a tail");}}3.15public class Exercise03_15 {public static void main(String[] args) {// Generate a lotteryint lottery = (int)(Math.random() * 1000);// Prompt the user to enter a guessjava.util.Scanner input = new java.util.Scanner(System.in); System.out.print("Enter your lottery pick (three digits): ");int guess = input.nextInt();// Get digitsint l1 = lottery / 100;int l2 = (lottery % 100) / 10; // l2 = (lottery / 10) % 10int l3 = lottery % 10;int g1 = guess / 100;int g2 = (guess % 100) / 10;int g3 = guess % 10;System.out.println("Lottery is " + lottery);// Check the guessif (guess == lottery)System.out.println("Exact match: you win $10,000");else if (g1 == l1 && g3 == l2 && g2 == l3 ||g2 == l1 && g1 == l2 && g3 == l3 ||g2 == l1 && g3 == l2 && g1 == l3 ||g3 == l1 && g1 == l2 && g2 == l3 ||g3 == l1 && g2 == l2 && g1 == l3)System.out.println("Match all digits: you win $3,000"); else if (g1 == l1 || g1 == l2 || g1 == l3 ||g2 == l1 || g2 == l2 || g2 == l3 ||g3 == l1 || g3 == l2 || g3 == l3)System.out.println("Match one digit: you win $1,000"); elseSystem.out.println("Sorry, no match");}}3.16public class Exercise03_16 {public static void main(String[] args) {double x = Math.random() * 100 - 50;double y = Math.random() * 200 - 100;System.out.println(x + ", " + y);}}3.17public class Exercise03_17 {public static void main(String[] args) {// Generate scissor, rock, paperint computerNumber = (int)(Math.random() * 3);// Prompt the user to enter scissor, rock, or paper java.util.Scanner input = new java.util.Scanner(System.in); System.out.print("scissor (0), rock (1), paper (2): ");int userNumber = input.nextInt();// Check the guessswitch (computerNumber) {case 0:if (userNumber == 0)System.out.print("The computer is scissor. You are scissor too. It is a draw");else if (userNumber == 1)System.out.print("The computer is scissor. You are rock. You won");else if (userNumber == 2)System.out.print("The computer is scissor. You are paper. You lost");break;case 1:if (userNumber == 0)System.out.print("The computer is rock. You are scissor. You lost");else if (userNumber == 1)System.out.print("The computer is rock. You are rock too. It is a draw");else if (userNumber == 2)System.out.print("The computer is rock. You are paper. You won");break;case 2:if (userNumber == 0)System.out.print("The computer is paper. You are scissor. You won");else if (userNumber == 1)System.out.print("The computer is paper. You are rock. You lost");else if (userNumber == 2)System.out.print("The computer is paper. You are paper too.It is a draw");break;}}}3.18public class Exercise03_18 {public static void main(String args[]) {Scanner input = new Scanner(System.in);System.out.print("Enter package weight: ");double w = input.nextDouble();if (w <= 1) {System.out.println("The shipping cost is $3.5");}else if (w <= 3) {System.out.println("The shipping cost is $5.5");}else if (w <= 10) {System.out.println("The shipping cost is $8.5");}else if (w <= 20) {System.out.println("The shipping cost is $10.5");}else {System.out.println("The package cannot be shipped");}}}3.19public class Exercise03_19 {public static void main(String[] args) {java.util.Scanner input = new java.util.Scanner(System.in); // Enter three edgesSystem.out.print("Enter three edges (length in double): ");double edge1 = input.nextDouble();double edge2 = input.nextDouble();double edge3 = input.nextDouble();。