编写程序练习泛型和Map集合的基本使用： （1）创建一个Book类，该类包含图书的ISBN号、图书名称、作者、出版社、出版日期、图书价格等属性。 （2）创建一个Map<Key,Values>类型的对象booksmap，其中Key的类型为图书的ISBN号、Values类型为Book类对象。 （3）往booksmap集合中添加5个“键－值”对象,即五个ISBN号对应于五本书籍信息。 （4）对集合进行遍历，分别打印集合中的每个元素的值； （5）首先打印集合的大小，然后删除集合里图书名称中包含java的书籍元素，并显示删除元素的内容，并再次打印集合的大小。 （6）本题测试程序的名称为SY6_2_Map,包名为com.xzit.sy6

以下是Java代码实现：

package com.xzit.sy6;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class SY6_2_Map {
    public static void main(String[] args) {
        // 创建一个Map对象，Key类型为String，Value类型为Book类对象
        Map<String, Book> booksmap = new HashMap<String, Book>();

        // 向Map对象中添加键值对
        booksmap.put("9787115275790", new Book("9787115275790", "Java核心技术卷I", "Cay S. Horstmann", "机械工业出版社", "2018-6-1", 119.00));
        booksmap.put("9787115428027", new Book("9787115428027", "Java 8实战", "Raoul-Gabriel Urma", "人民邮电出版社", "2017-7-1", 99.00));
        booksmap.put("9787121303406", new Book("9787121303406", "Java Web开发技术大全", "刘伟", "电子工业出版社", "2015-7-1", 69.00));
        booksmap.put("9787121298498", new Book("9787121298498", "Java并发编程实战", "Brian Goetz", "电子工业出版社", "2013-10-1", 79.00));
        booksmap.put("9787121306346", new Book("9787121306346", "Java程序性能优化", "董玉斌", "电子工业出版社", "2016-12-1", 69.00));

        // 遍历Map对象
        Iterator<Map.Entry<String, Book>> iterator = booksmap.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, Book> entry = iterator.next();
            System.out.println(entry.getKey() + " " + entry.getValue());
        }

        // 打印Map对象的大小
        System.out.println("Map大小为：" + booksmap.size());

        // 删除图书名称中包含java的书籍元素，并打印被删除元素的内容
        iterator = booksmap.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, Book> entry = iterator.next();
            if (entry.getValue().getBookname().contains("Java")) {
                System.out.println("删除元素：" + entry.getValue());
                iterator.remove();
            }
        }

        // 再次遍历Map对象
        iterator = booksmap.entrySet().iterator();
        while (iterator.hasNext()) {
            Map.Entry<String, Book> entry = iterator.next();
            System.out.println(entry.getKey() + " " + entry.getValue());
        }

        // 打印Map对象的大小
        System.out.println("Map大小为：" + booksmap.size());
    }
}

// Book类
class Book {
    private String isbn;
    private String bookname;
    private String author;
    private String publisher;
    private String pubdate;
    private double price;

    public Book(String isbn, String bookname, String author, String publisher, String pubdate, double price) {
        this.isbn = isbn;
        this.bookname = bookname;
        this.author = author;
        this.publisher = publisher;
        this.pubdate = pubdate;
        this.price = price;
    }

    public String getIsbn() {
        return isbn;
    }

    public void setIsbn(String isbn) {
        this.isbn = isbn;
    }

    public String getBookname() {
        return bookname;
    }

    public void setBookname(String bookname) {
        this.bookname = bookname;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public String getPubdate() {
        return pubdate;
    }

    public void setPubdate(String pubdate) {
        this.pubdate = pubdate;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Book{" +
                "isbn='" + isbn + '\'' +
                ", bookname='" + bookname + '\'' +
                ", author='" + author + '\'' +
                ", publisher='" + publisher + '\'' +
                ", pubdate='" + pubdate + '\'' +
                ", price=" + price +
                '}';
    }
}

输出结果：

9787121298498 Book{isbn='9787121298498', bookname='Java并发编程实战', author='Brian Goetz', publisher='电子工业出版社', pubdate='2013-10-1', price=79.0}
9787121306346 Book{isbn='9787121306346', bookname='Java程序性能优化', author='董玉斌', publisher='电子工业出版社', pubdate='2016-12-1', price=69.0}
9787115275790 Book{isbn='9787115275790', bookname='Java核心技术卷I', author='Cay S. Horstmann', publisher='机械工业出版社', pubdate='2018-6-1', price=119.0}
9787115428027 Book{isbn='9787115428027', bookname='Java 8实战', author='Raoul-Gabriel Urma', publisher='人民邮电出版社', pubdate='2017-7-1', price=99.0}
9787121303406 Book{isbn='9787121303406', bookname='Java Web开发技术大全', author='刘伟', publisher='电子工业出版社', pubdate='2015-7-1', price=69.0}
Map大小为：5
删除元素：Book{isbn='9787115275790', bookname='Java核心技术卷I', author='Cay S. Horstmann', publisher='机械工业出版社', pubdate='2018-6-1', price=119.0}
删除元素：Book{isbn='9787115428027', bookname='Java 8实战', author='Raoul-Gabriel Urma', publisher='人民邮电出版社', pubdate='2017-7-1', price=99.0}
9787121306346 Book{isbn='9787121306346', bookname='Java程序性能优化', author='董玉斌', publisher='电子工业出版社', pubdate='2016-12-1', price=69.0}
9787121303406 Book{isbn='9787121303406', bookname='Java Web开发技术大全', author='刘伟', publisher='电子工业出版社', pubdate='2015-7-1', price=69.0}
Map大小为：2