面向对象练习

目录

1. (LeetCode 第169题)给定一个大小为 n 的数组 nums ，返回其中的多数元素。多数元素是指在数组中出现次数大于 n/2 的元素。

2. 综合案例（用户博客管理系统）

1. （抽象类）定义一个抽象的"Role"类 有姓名 年龄 性别等成员变量

2. （抽象类）品尝饮料

1. (LeetCode 第169题)给定一个大小为 n 的数组 nums ，返回其中的多数元素。多数元素是指在数组中出现次数大于 n/2 的元素。

例如：[1,1,1,1,2,3,3]，多数元素为1

方法1：排序数组，找最中间的数

如果将数组 nums 中的所有元素按照单调递增或单调递减的顺序排序，那么下标为nums.lenght/2的元素（下标从 0 开始）即最中间的数一定是众数。

方法2：抵消法

循环遍历数组，下一个数相同时计数加1，下一个数不同计数就减去1，当为count==0时，把num[i]赋值给众数，直到最后，得到的数就是众数

<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">import java.util.Arrays;

public class FindRepeatNum {
    public static void main(String[] args) {
//      int[] nums = { 1, 1, 1, 1, 2, 3, 3 };
        int[] nums = { 2, 2, 1, 1, 1, 2, 2 };
//      int[] nums = { 1, 3, 1, 1, 4, 1, 1, 5, 1, 1, 6, 2, 2 };
        int result = findRepeatMax(nums);
        System.out.println("出现次数大于" + nums.length / 2 + "的元素为" + result);
        int result1 = majorElements(nums);
        System.out.println("出现次数大于" + nums.length / 2 + "的元素为" + result1);
    }

    /*
     * 给定一个大小为 n 的数组 nums，返回其中的多数元素。
     * 多数元素是指在数组中出现次数大于 n/2 的元素。
     */
    private static int findRepeatMax(int[] nums) {
        Arrays.sort(nums);
        return nums[nums.length / 2];
    }

    // nums[i]  1 2 2 1 1 1 1 2 3
    // major    1 / 2 / 1 1 1 1 1
    // count    1 0 1 0 1 2 3 2 1

    // nums[i]  1 2 2 1 1 1 1 2 3
    // major    1 2 2 2 1 1 1 1 1
    //            0     0
    // count.   1 1 2 1 1 2 3 2 1
    private static int majorElements(int[] nums) {
        int majority = nums[0];
        int count = 1;
        for (int i = 1; i < nums.length; i++) {
            if (count == 0) {
                count++;
                majority = nums[i];
            } else if (nums[i] == majority) {
                count++;
            } else if (nums[i] != majority) {
                count--;
            }
//          if (count == 0) {
//              count++;
//              majority = nums[i];
//          }
        }
        return majority;
    }
}</pre>

结果：

2. 综合案例（用户博客管理系统）

Bolg类（抽象类）：

<pre class="prettyprint hljs java" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

public abstract class Blog {
    final static int Board = 1; // 板块
    final static int Article = 2; // 文章
    final static int Author = 3; // 作者
    final static int Comment = 4; // 作者

    // 抽象方法：showPage()页面展示
    public abstract void showPage();
}</pre>

Board类：

<pre class="prettyprint hljs kotlin" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

//import java.util.Arrays;

public class Board extends Blog {
    private int id; // 板块id
    private String name; // 板块名称
    private String intro; // 简介或描述

//  开发中尽量使用单项关联，双向关联会造成冗余
//  private Article[] articles;

    @Override
    public String toString() {
        return name;
    }

    public Board() {
        super();
    }

    public Board(int id, String name, String intro) {
        super();
        this.id = id;
        this.name = name;
        this.intro = intro;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIntro() {
        return intro;
    }

    public void setIntro(String intro) {
        this.intro = intro;
    }

    @Override
    public void showPage() {
        // TODO Auto-generated method stub
        System.out.println("********************模块详情********************");
        System.out.println("  作者编号：");
        System.out.println("\t" + this.getId());
        System.out.println("  作者姓名");
        System.out.println("\t" + this.getName());
        System.out.println("  作者简介：");
        System.out.println("\t" + this.getIntro());
        System.out.println("************************************************");
        System.out.println();
    }

}</pre>

Author类：

<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

//import java.util.Arrays;

public class Author extends Blog {
    private int id; // 作者id
    private String name; // 姓名
    private String gender; // 性别
    private int age; // 年龄
    private String intro = "作者很懒，什么业没留下~"; // 简介或描述
//  private Article[] articles;

    @Override
    public String toString() {
        return name;
    }

    public Author(int id, String name, String gender, int age, String intro) {
        super();
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
        this.intro = intro;
    }

    public Author() {
        super();
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getIntro() {
        return intro;
    }

    public void setIntro(String intro) {
        this.intro = intro;
    }

    @Override
    public void showPage() {
        // 作者详情页
        System.out.println("********************作者详情********************");
        System.out.println("  作者编号：");
        System.out.println("\t" + this.getId());
        System.out.println("  作者姓名");
        System.out.println("\t" + this.getName());
        System.out.println("  作者性别：");
        System.out.println("\t" + this.getGender());
        System.out.println("  作者年龄：");
        System.out.println("\t" + this.getAge());
        System.out.println("  作者简介：");
        System.out.println("\t" + this.getIntro());
        System.out.println("************************************************");
        System.out.println();
    }
}</pre>

Article类：

<pre class="prettyprint hljs kotlin" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

import java.util.Date;

//import java.util.Arrays;

public class Article extends Blog {
    private int id; // 文章id
    private String tittle; // 标题
    private String content; // 内容
    private Author Author; // 作者
    private Board board; // 所属板块
    private Date publishTime; // 发布时间
    private Date modifyTime; // 修改时间
    @Override
    public String toString() {
        return tittle;
    }

    public Article(int id, String tittle, String content, Author Author, Board board, Date publishTime,
            Date modifyTime) {
        super();
        this.id = id;
        this.tittle = tittle;
        this.content = content;
        this.Author = Author;
        this.board = board;
        this.publishTime = publishTime;
        this.modifyTime = modifyTime;
    }

    public Article() {
        super();
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTittle() {
        return tittle;
    }

    public void setTittle(String tittle) {
        this.tittle = tittle;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Author getAuthor() {
        return Author;
    }

    public void setAuthor(Author Author) {
        this.Author = Author;
    }

    public Board getBoard() {
        return board;
    }

    public void setBoard(Board board) {
        this.board = board;
    }

    public Date getPublishTime() {
        return publishTime;
    }

    public void setPublishTime(Date publishTime) {
        this.publishTime = publishTime;
    }

    public Date getModifyTime() {
        return modifyTime;
    }

    public void setModifyTime(Date modifyTime) {
        this.modifyTime = modifyTime;
    }

    @Override
    public void showPage() {
        // 文章详情页
        System.out.println("********************文章详情********************");
        System.out.println("  文章编号：");
        System.out.println("\t" + this.getId());
        System.out.println("  文章标题：");
        System.out.println("\t" + this.getTittle());
        System.out.println("  文章作者：");
        System.out.println("\t" + this.getAuthor());
        System.out.println("  发布时间：");
        System.out.println("\t" + this.getPublishTime());
        System.out.println("  修改时间：");
        System.out.println("\t" + this.getModifyTime());
        System.out.println("  文章内容：");
        System.out.println("\t" + this.getContent());
        System.out.println("  所属板块：");
        System.out.println("\t" + this.getBoard());
        System.out.println("************************************************");
        System.out.println();
    }
}</pre>

Comment类：

<pre class="prettyprint hljs kotlin" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

import java.util.Date;

public class Comment extends Blog {
    private int id; // 回复id
    private String content; // 内容
    private Author Author; // 作者
    private Date publishTime; // 发布时间
    private Date modifyTime; // 修改时间
    private Article article; // 文章

    @Override
    public String toString() {
        return content;
    }

    public Comment(int id, String content, Author Author, Date publishTime, Date modifyTime, Article article) {
        super();
        this.id = id;
        this.content = content;
        this.Author = Author;
        this.publishTime = publishTime;
        this.modifyTime = modifyTime;
        this.article = article;
    }

    public Comment() {
        super();
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public Author getAuthor() {
        return Author;
    }

    public void setAuthor(Author Author) {
        this.Author = Author;
    }

    public Date getPublishTime() {
        return publishTime;
    }

    public void setPublishTime(Date publishTime) {
        this.publishTime = publishTime;
    }

    public Date getModifyTime() {
        return modifyTime;
    }

    public void setModifyTime(Date modifyTime) {
        this.modifyTime = modifyTime;
    }

    public Article getArticle() {
        return article;
    }

    public void setArticle(Article article) {
        this.article = article;
    }

    @Override
    public void showPage() {
        // 文章详情页
        System.out.println("********************评论详情********************");
        System.out.println("  评论编号：");
        System.out.println("\t" + this.getId());
        System.out.println("  评论作者：");
        System.out.println("\t" + this.getAuthor());
        System.out.println("  发布时间：");
        System.out.println("\t" + this.getPublishTime());
        System.out.println("  修改时间：");
        System.out.println("\t" + this.getModifyTime());
        System.out.println("  评论内容：");
        System.out.println("\t" + this.getContent());
        System.out.println("  所属文章：");
        System.out.println("\t" + this.getArticle());
        System.out.println("************************************************");
        System.out.println();
    }
}</pre>

Test类：

<pre class="prettyprint hljs gradle" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer1;

import java.util.Date;
import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Article article = new Article();
        Author author = new Author();
        Board board = new Board();
        Comment comment = new Comment();

        author.setId(100001);
        author.setName("zhang");
        author.setAge(20);
        author.setGender("男");
        author.setIntro("入门程序猿，请多指教！");

        board.setId(1);
        board.setName("Java");
        board.setIntro("Java面向对象编程，文章汇聚地");

        article.setId(1001);
        article.setTittle("面向对象三大特征");
        article.setAuthor(author);
        article.setPublishTime(new Date());
        article.setModifyTime(new Date());
        article.setContent("面向对象的三大特征主要为：封装、继承、多态\n" + "\t    1\. 封装\n" + "\t    2\. 继承\n" + "\t    3\. 多态\n");
        article.setBoard(board);
//      article.showPage();

        comment.setId(1);
        comment.setAuthor(author);
        comment.setPublishTime(new Date());
        comment.setModifyTime(new Date());
        comment.setContent("作者，可以详细说一下什么是封装吗\n");
        comment.setArticle(article);
        while (true) {
            Blog page = null;
            System.out.println("        用户博客管理系统");
            System.out.println("************************************************");
            System.out.println();
            System.out.println("\t\t1\. 模块详情");
            System.out.println();
            System.out.println("\t\t2\. 文章详情");
            System.out.println();
            System.out.println("\t\t3\. 作者详情");
            System.out.println();
            System.out.println("\t\t4\. 评论详情");
            System.out.println();
            System.out.println("\t\t5\. 退出");
            System.out.println();
            System.out.println("************************************************");
            System.out.print("请输入你的选项(1-5)：");
            switch (scanner.nextInt()) {
            case Blog.Board:
                page = board;
                break;
            case Blog.Article:
                page = article;
                break;
            case Blog.Author:
                page = author;
                break;
            case Blog.Comment:
                page = comment;
                break;
            default:
                System.exit(1);
                break;
            }
            System.out.println();
            page.showPage();
        }

    }
}</pre>

结果：

3. （抽象类）定义一个抽象的"Role"类 有姓名 年龄 性别等成员变量

1. 要求尽可能隐藏所有变量(能够私有就私有,能够保护就不要公有)

再通过GetXXX()和SetXXX()方法对各变量进行读写。具有一个抽象的play()方法

该方法不返回任何值 同时至少定义两个构造方法。Role类中要体现出this的几种用法。

2. 从Role类派生出一个"Employee"类 该类具有Role类的所有成员

构造方法除外 并扩展 salary成员变量 同时增加一个静态成员变量“职工编号 ID ”。

同样要有至少两个构造方法 要体现出this和super的几种用法

还要求覆盖play()方法 并提供一个final sing()方法。

3. "Manager"类继承"Employee"类 有一个final成员变量"vehicle"

4. 在main()方法中制造Manager和Employee对象,并测试这些对象的方法

Role类：

<pre class="prettyprint hljs java" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer2;

public abstract class Role {
    private String name;
    private int age;
    private String gender;

    @Override
    public String toString() {
        return "姓名：" + name + "，年龄：" + age + "，性别：" + gender + "]";
    }

    public Role() {
        super();
    }

    public Role(String name, int age, String gender) {
        super();
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public abstract void play();
}</pre>

Employee类：

<pre class="prettyprint hljs java" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer2;

public class Employee extends Role {
    private double salary;
    private static int id = 1001;

    @Override
    public String toString() {
        return "姓名：" + super.getName() + "，工号：" + Employee.id + "，年龄：" + super.getAge() + 
                "，性别：" + super.getGender() + "，薪水：" + this.salary;
    }

    public Employee() {
        super();
    }

    public Employee(String name, int id, int age, String gender, double salary) {
        super(name, age, gender); // 调用父类的构造方法，一定要放在方法的首个语句
        this.salary = salary;
        Employee.id = id;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public static int getId() {
        return id;
    }

    public static void setId(int id) {
        Employee.id = id;
    }

    @Override
    public void play() {
        System.out.println(super.getAge() + "，这个年纪就应该玩！");
;
    }

    public final void sing() {
        System.out.println(this.getName() + "，放声歌唱吧");
    }
}</pre>

Manager类：

<pre class="prettyprint hljs scala" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer2;

public class Manager extends Employee {
    private final String vehicle = "公交";

    @Override
    public String toString() {
        return "姓名：" + super.getName() + "，工号：" + super.getId() + "，年龄：" + super.getAge() + 
                "，性别：" + super.getGender() + "，薪水：" + super.getSalary() + "，交通工具：" + this.vehicle;
    }

    public String getVehicle() {
        return vehicle;
    }
}</pre>

Test类：

<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer2;

public class Test {
    public static void main(String[] args) {
        Manager manager = new Manager();
        manager.setAge(20);
        manager.play();
        manager.setName("zhang");
        manager.sing();
        manager.setGender("男");
        manager.setSalary(10000);
        System.out.println(manager);
        System.out.println(manager.getVehicle());

        Employee employee1 = new Employee();
        employee1.setName("wang");
        employee1.setAge(30);
        employee1.setGender("男");
        employee1.setSalary(4000);
        System.out.println(employee1);
        employee1.play();
        employee1.sing();
        Employee employee = new Employee("li", 1008, 25, "男", 5000);
        System.out.println(employee);
        employee.play();
        employee.sing();

        Role r1 = new Manager();
        r1.setAge(18);
        r1.play();
//      r1.sing();
        System.out.println(r1);
    }
}</pre>

结果：

4. （抽象类）品尝饮料

1、建立一个Java抽象类Drink，应当

• a、声明一个抽象方法taste() 该方法负责输出饮料的味道
• b、声明int型常量来代表不同的饮料类型 咖啡、啤酒、牛奶
• c、声明静态工厂方法getDrink(int drinkType) 根据传入的参数创建不同的饮料对象 并返回该对象 建议使用switch语句。该方法要求声明DrinkNotFoundException 当没有相对应的饮料类型时 抛出该异常。

2、建立Drink的具体子类

• a、分别建立Drink的子类 Coffee 代表咖啡 Beer 代表啤酒 Milk 代表牛奶 ;
• b、实现taste()方法 要求在控制台打印各自的味道特征。

3、建立异常类DrinkNotFoundException

• a、继承Exception
• b、在Drink的 方 法getDrink(int drinkType)中 声 明 引 发DrinkNotFoundException异常 当传入的参数没有相对应的饮料类型时 抛出异常。
• c、在使用getDrink方法的类中捕捉该异常。

4、建立Test测试类 测试以上内容的正确性

• a、编写main方法 通过命令行传参的方式传入某种饮料的类型。
• b、在main方法中 调用Drink类的getDrink方法 获得相应的饮料对象。注意捕获DrinkNotFoundException。
• c、然后调用该饮料对象的taste()方法 输出该饮料的味道。

5、编译程序 并运行。

注意事项：1、仔细审题 把题目要求理解准确 2、请注意多态性的运用 3、请注意代码的书写、命名符合规范 应有适当的注释

Drink类：

<pre class="prettyprint hljs java" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer3;

public abstract class Drink {
    // 声明int型常量来代表不同的饮料类型 咖啡、啤酒、牛奶
    final static int COOFFEE = 1; // 咖啡
    final static int BEER = 2; // 啤酒
    final static int MILK = 3; // 牛奶

    // 声明静态工厂方法getDrink(int drinkType) 
    // 根据传入的参数创建不同的饮料对象,并返回该对象
    public static Drink getDrink(int drinkType) throws DrinkNotFoundException {
        switch (drinkType) {
        case COOFFEE:
            Coffee coffee = new Coffee();
            return coffee;
        case BEER:
            Beer beer = new Beer();
            return beer;
        case MILK:
            Milk milk = new Milk();
            return milk;
        default:
            throw new DrinkNotFoundException("找不的对应类型的饮料！");
        }
    }

    // 声明一个抽象方法taste(),该方法负责输出饮料的味道
    public abstract void taste();
}</pre>

Coffee类：

<pre class="prettyprint hljs scala" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer3;

public class Coffee  extends Drink {

    // 实现taste()方法
    @Override
    public void taste() {
        System.out.println("咖啡是厚重的苦味");
    }

}</pre>

Beer类：

<pre class="prettyprint hljs scala" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer3;

public class Beer extends Drink {

    // 实现taste()方法
    @Override
    public void taste() {
        // 打印各自的味道特征。
        System.out.println("啤酒是略微的苦涩味道");
    }

}</pre>

MilK类：

<pre class="prettyprint hljs scala" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer3;

public class Milk extends Drink {

    // 实现taste()方法
    @Override
    public void taste() {
        System.out.println("牛奶奶香味特别浓的");
    }

}</pre>

DrinkNotFoundException异常类：

<pre class="prettyprint hljs scala" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, &quot;Courier New&quot;, monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; overflow-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">package com.openlab.day13.exer3;

// 建立异常类DrinkNotFoundException，继承Exception 
public class DrinkNotFoundException extends Exception {
    static final long serialVersionUID = -3387516993124229948L;

    public DrinkNotFoundException(String message) {
        super(message);
    }
}</pre>

Test类：

结果：