private HashMap<String, ArrayList<MailItem>> items;
/**
* Construct a mail server.
*/
public MailServer()
{
items = new HashMap<String, ArrayList<MailItem>>();
}
您如何在类中添加一种方法来遍历用户,打印出每个用户名,并打印出与该用户关联的所有电子邮件?基本上,您如何编写代码来遍历用户的哈希图,然后遍历用户的数组列表,并打印出每个用户的所有值?
答案 0 :(得分:0)
public static void print(Map<String, List<MailItem>> map) {
map.forEach((userName, mailItems) -> {
System.out.println("User name: " + userName);
System.out.println("User emails: " + mailItems.stream().map(MailItem::getEmail).collect(Collectors.joining(",")));
System.out.println();
});
}