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);elsesetPrice(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;}@Overridepublic 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;}@Overridepublic 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;}@Overridepublic String toString() {return "GirlFriend{" +"name='" + name + '\'' +'}';}}
