Java从入门到精通章节练习题——第六章

亦凉 2023-09-27 12:01 124阅读 0赞

#### Java从入门到精通章节练习题——第六章 ####

*  Exercise 1 简易计算器
 *  Exercise 2 购买电影票
 *  Exercise 3 计算平均分
 *  Exercise 4 厘米与英寸互转
 *  Exercise 5 多种权限的工具
 *  Exercise 6 计算矩形的面积
 *  Exercise 7 判断是否存在运行时参数
 *  Exercise 8 单例模式

## Exercise 1 简易计算器 ##

package chapter6;
    
    public class Exercise1 {
        
        public static double res = 0;
    
        //完成两个数加法运算的静态方法
        static public void add(double num1, double num2) {
        
            res = num1 + num2;
            System.out.println(num1 + "加上" + num2 + "的结果为" + res);
        }
    
        //完成两个数减法运算的静态方法
        static public void sub(double num1, double num2) {
        
            res = num1 - num2;
            System.out.println(num1 + "减去" + num2 + "的结果为" + res);
        }
    
        //完成两个数乘法运算的静态方法
        static public void mul(double num1, double num2) {
        
            res = num1 * num2;
            System.out.println(num1 + "c乘以" + num2 + "的结果为" + res);
        }
    
        //完成两个数除法运算的静态方法
        static public void div(double num1, double num2) {
        
            res = num1 / num2;
            System.out.println(num1 + "除以" + num2 + "的结果为" + res);
        }
    
        public static void main(String[] args) {
        
            add(4.4, 7.11);
            sub(8.9, 2.28);
            mul(5.2, 13.14);
            div(92, 89);
        }
    }

## Exercise 2 购买电影票 ##

package chapter6;
    
    /**
     * 购买电影票
     */
    public class Exercise2 {
        
    
        public static void main(String[] args) {
        
            Info list1 = new Info("李明", 20);
            Info list2 = new Info("钱丽", 16);
            Info list3 = new Info("周刚", 8);
            Info list4 = new Info("吴红", 32);
            Info[] oneList = new Info[4];
            oneList[0] = list1;
            oneList[1] = list2;
            oneList[2] = list3;
            oneList[3] = list4;
    
            //输出显示
            System.out.println("姓名\t" + "年龄\t" + "票价(元)");
            System.out.println("——————————————————————————————————");
            for (int i = 0; i < 4; i++) {
        
                System.out.println(oneList[i]);//重写了toString方法，输出对象时输出信息
            }
        }
    
    }
    
    class Info {
        
    
        private int age;//年龄
        private double price;//票价
        private String name;//姓名
    
        public Info() {
        
        }
    
        //构造方法中判断得出并设置价格
        public Info(String name, int age) {
        
            this.age = age;
            this.name = name;
            if (age >= 18)
                setPrice(40);
            else
                setPrice(20);
        }
    
        public int getAge() {
        
            return age;
        }
    
        public void setAge(int age) {
        
            this.age = age;
        }
    
        public double getPrice() {
        
            return price;
        }
    
        public void setPrice(double price) {
        
            this.price = price;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        @Override
        public String toString() {
        
            return name + "\t" + age + "\t\t" + price;
        }
    }

## Exercise 3 计算平均分 ##

package chapter6;
    
    /**
     * 计算平均分
     */
    public class Exercise3 {
        
        private int num;
        private String name;
        private double chinese;
        private double math;
        private double english;
        private double avg;
    
        public Exercise3(int num, String name, double chinese, double math, double english) {
        
            this.num = num;
            this.name = name;
            this.chinese = chinese;
            this.math = math;
            this.english = english;
        }
    
        public int getNum() {
        
            return num;
        }
    
        public void setNum(int num) {
        
            this.num = num;
        }
    
        public String getName() {
        
            return name;
        }
    
        public void setName(String name) {
        
            this.name = name;
        }
    
        public double getChinese() {
        
            return chinese;
        }
    
        public void setChinese(double chinese) {
        
            this.chinese = chinese;
        }
    
        public double getMath() {
        
            return math;
        }
    
        public void setMath(double math) {
        
            this.math = math;
        }
    
        public double getEnglish() {
        
            return english;
        }
    
        public void setEnglish(double english) {
        
            this.english = english;
        }
    
        public double getAvg() {
        
            return avg;
        }
    
        public void setAvg(double avg) {
        
            this.avg = avg;
        }
    
        @Override
        public String toString() {
        
            return num + "\t\t" + name + '\t' + chinese +
                    "\t" + math +
                    "\t" + english +
                    "\t" + avg
                    ;
        }
    }
    
    class ShowInfo {
        
        public static void main(String[] args) {
        
    
            //保存学生成绩
            Exercise3 stu1 = new Exercise3(1, "张三", 91.5, 98, 89);
            stu1.setAvg((stu1.getChinese() + stu1.getEnglish() + stu1.getMath())/3);
            Exercise3 stu2 = new Exercise3(2, "李四", 96, 98.5, 93);
            stu2.setAvg((stu2.getChinese() + stu2.getEnglish() + stu2.getMath())/3);
            Exercise3 stu3 = new Exercise3(3, "王五", 97, 100, 98.5);
            stu3.setAvg((stu3.getChinese() + stu3.getEnglish() + stu3.getMath())/3);
            Exercise3 stu4 = new Exercise3(4, "钱六", 77, 83, 81);
            stu4.setAvg((stu4.getChinese() + stu4.getEnglish() + stu4.getMath())/3);
            System.out.println("学号" + "\t" + "姓名" + "\t" + "语文" + "\t" + "数学" + "\t" + "英语" + "\t" + "平均分");
            System.out.println("—————————————————————————————————————————————————————————————————");
            System.out.println(stu1);
            System.out.println(stu2);
            System.out.println(stu3);
            System.out.println(stu4);
        }
    
    }

## Exercise 4 厘米与英寸互转 ##

package chapter6;
    
    import java.util.Scanner;
    
    /**
     * 厘米与英寸互转
     */
    public class Exercise4 {
        
        private double cm;
        private double in;
        //1 英寸 = 2.54 厘米
    
        public static void main(String[] args) {
        
            boolean loop = true;
            double cm;//厘米
            double in;//英寸
            do {
        
                Scanner scanner = new Scanner(System.in);
                System.out.println("请输入选项(1.厘米->英寸 2.英寸->厘米 0.退出)");
                int key = scanner.nextInt();
                //选择转换方向
                switch (key) {
        
                    case 1:
                        System.out.print("请输入厘米数:");
                        cm = scanner.nextDouble();
                        in = 2.54 * cm;
                        System.out.println(in);
                        break;
                    case 2:
                        System.out.println("请输入英寸数:");
                        in = scanner.nextDouble();
                        cm = in / 2.54;
                        System.out.println(cm);
                        break;
                    case 0:
                        loop = false;
                }
            } while (loop);
        }
    }

## Exercise 5 多种权限的工具 ##

package chapter6;
    
    /**
     * 多种权限的工具
     */
    public class Exercise5 {
        
        public void getRandomNumber() {
        }//对外公开
        protected void setNumber() {
        }//对子类和同一个包中的类公开
        private void sort() {
        }//只有类本身可以访问,不对外公开
    }

## Exercise 6 计算矩形的面积 ##

package chapter6;
    
    /**
     * 计算矩形的面积
     */
    public class Exercise6 {
        
        private double length;//长
        private double width;//宽
    
        //构造方法，初始化长和宽
        public Exercise6(double length, double width) {
        
            this.length = length;
            this.width = width;
        }
        
        //计算面积方法
        public double getArea() {
        
            return length * width;
        }
    
        public static void main(String[] args) {
        
            double area = new Exercise6(10, 5).getArea();
            System.out.println(area);
        }
    }

## Exercise 7 判断是否存在运行时参数 ##

package chapter6;
    
    /**
     * 判断是否存在运行时参数
     */
    public class Exercise7 {
        
        public static void main(String[] args) {
        
            if (args.length == 0) {
        
                System.out.println("无运行参数");
            } else {
        
                for (int i = 0; i < args.length; i++) {
        
    
                    System.out.println(args[i]);
                }
            }
            
        }
    }

## Exercise 8 单例模式 ##

package chapter6;
    
    /**
     * 单例模式
     */
    public class Exercise8 {
        
        public static void main(String[] args) {
        
            GirlFriend instance = GirlFriend.getInstance();
            System.out.println(instance);
        }
    }
    
    class GirlFriend {
        
    
        private String name;
        //创建静态对象，保证只创建一次对象
        private static GirlFriend gf = new GirlFriend("小红");
    
        //将构造器私有化
        public GirlFriend(String name) {
        
            System.out.println("有参构造方法被调用");
            this.name = name;
        }
    
        //得到创建的对象
        public static GirlFriend getInstance() {
        
            return gf;
        }
    
        @Override
        public String toString() {
        
            return "GirlFriend{" +
                    "name='" + name + '\'' +
                    '}';
        }
    }