帮我用Java写一个1、有四个类，基类Store，直接或间接派生出Mobile、Mp3Player、Product这几个类，其中Mobile、Mp3Player是Product的子类，Product类实现Comparable接口，重写了Comparable接口中方法compareTo，实现了product对象按照价格排序。基本要求：（1）写出Product、Mobile、Mp3Player类的源码，是否有构造函数根据输出结果自行决定。（2）在主类Store中实例化多个Mobile类与Mp3Player的实例，分别将这些实例用ArrayList与LinkedList存放，最后用StringBuider存放并将其输出。（3）用迭代器（iterator）将实例对象输出（要求用加强型for循环）。 2、已知某学校的教学课程内容安排如下 ： 完成下列要求：（1）使用一个Map，以老师的名字作为键，以老师教授的课程名作为值，表示上述课程安排。（2）增加了一位新老师Allen 教JDBC。（3）Lucy 改为教CoreJava。（4）用两种方式遍历Map，输出所有的老师及老师教授的课程。（5）利用Map，输出所有教JSP 的老师。

1. 代码如下：

Product类：

public class Product implements Comparable<Product> {
    private String name;
    private double price;

    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public double getPrice() {
        return price;
    }

    @Override
    public int compareTo(Product o) {
        if (this.price > o.getPrice()) {
            return 1;
        } else if (this.price < o.getPrice()) {
            return -1;
        } else {
            return 0;
        }
    }
}

Mobile类：

public class Mobile extends Product {
    private String brand;

    public Mobile(String name, double price, String brand) {
        super(name, price);
        this.brand = brand;
    }

    public String getBrand() {
        return brand;
    }
}

Mp3Player类：

public class Mp3Player extends Product {
    private int storage;

    public Mp3Player(String name, double price, int storage) {
        super(name, price);
        this.storage = storage;
    }

    public int getStorage() {
        return storage;
    }
}

Store类：

import java.util.*;

public class Store {
    public static void main(String[] args) {
        ArrayList<Mobile> mobileList = new ArrayList<>();
        mobileList.add(new Mobile("iPhone", 999.99, "Apple"));
        mobileList.add(new Mobile("Galaxy S21", 899.99, "Samsung"));

        LinkedList<Mp3Player> mp3PlayerList = new LinkedList<>();
        mp3PlayerList.add(new Mp3Player("iPod Touch", 199.99, 64));
        mp3PlayerList.add(new Mp3Player("Walkman", 149.99, 32));

        StringBuilder sb = new StringBuilder();
        for (Mobile mobile : mobileList) {
            sb.append(mobile.getName()).append(", ").append(mobile.getBrand()).append(", $").append(mobile.getPrice()).append("\n");
        }
        for (Mp3Player mp3Player : mp3PlayerList) {
            sb.append(mp3Player.getName()).append(", ").append(mp3Player.getStorage()).append("GB, $").append(mp3Player.getPrice()).append("\n");
        }
        System.out.println(sb.toString());

        Iterator<Mobile> mobileIterator = mobileList.iterator();
        while (mobileIterator.hasNext()) {
            Mobile mobile = mobileIterator.next();
            System.out.println(mobile.getName() + ", " + mobile.getBrand() + ", $" + mobile.getPrice());
        }

        for (Mp3Player mp3Player : mp3PlayerList) {
            System.out.println(mp3Player.getName() + ", " + mp3Player.getStorage() + "GB, $" + mp3Player.getPrice());
        }
    }
}

2. 代码如下：

import java.util.*;

public class School {
    public static void main(String[] args) {
        Map<String, String> courseMap = new HashMap<>();
        courseMap.put("Tom", "Java");
        courseMap.put("Jerry", "Python");
        courseMap.put("Lucy", "JavaScript");

        courseMap.put("Allen", "JDBC");
        courseMap.put("Lucy", "CoreJava");

        for (Map.Entry<String, String> entry : courseMap.entrySet()) {
            System.out.println(entry.getKey() + " teaches " + entry.getValue());
        }

        System.out.println();

        Set<Map.Entry<String, String>> entrySet = courseMap.entrySet();
        Iterator<Map.Entry<String, String>> iterator = entrySet.iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, String> entry = iterator.next();
            if (entry.getValue().equals("JSP")) {
                System.out.println(entry.getKey());
            }
        }
    }
}