测试类

package com.imooc.chapter14test;

import java.util.*;

public class BookTest {
    public static void main(String[] args) {
        //创建三个ArrayList对应3个类别，并存放书籍元素
        List<String> classicBooks = new ArrayList<>();
        classicBooks.add("三国演义");
        classicBooks.add("西游记");
        classicBooks.add("红楼梦");
        classicBooks.add("水浒传");
        //-----------------------------------------
        List<String> modernBooks = new ArrayList<>();
        modernBooks.add("朝花夕拾");
        modernBooks.add("繁星");
        modernBooks.add("春水");
        modernBooks.add("边城");
        //-----------------------------------------
        List<String> sifiBooks = new ArrayList<>();
        sifiBooks.add("流浪地球");
        sifiBooks.add("宇宙往事");
        sifiBooks.add("三体");
        sifiBooks.add("死神永生");
        sifiBooks.add("沙丘");
        sifiBooks.add("银河帝国");
        //创建HashMap
        Map<String, List<String>> bookMap = new HashMap<>();
        bookMap.put("古典文学", classicBooks);
        bookMap.put("近代文学", modernBooks);
        bookMap.put("科幻文学", sifiBooks);
        //通过entryPoint遍历HashMap
        Set<Map.Entry<String, List<String>>> entrySet = bookMap.entrySet();
        for (Map.Entry<String, List<String>> item:
             entrySet) {
            String key = item.getKey();
            List<String> value = item.getValue();
            System.out.println(key + ": " + value);
        }
    }
}