java - 如何从 iterator() 中以正确的顺序获取元素

Question

这是我将数据存储到 HashMap 并使用迭代器显示数据的代码

public static void main(String args[]) {
    HashMap<String, String> hm = new HashMap<String, String>();
    hm.put("aaa", "111");
    hm.put("bbb", "222");
    hm.put("ccc", "333");
    hm.put("ddd", "444");
    hm.put("eee", "555");
    hm.put("fff", "666");

    Iterator iterator = hm.keySet().iterator();

    while (iterator.hasNext()) {
        String key = (String) iterator.next();
        String val = hm.get(key);

        System.out.println(key + " " + val);
    }
}

但它不是按照我存储的顺序显示的。有人可以告诉我我哪里出错了吗？如何获取订单中的元素？

Answer 1

A HashMap没有保证顺序:

This class makes no guarantees as to the order of the map;

使用 LinkedHashMap .

Hash table and linked list implementation of the Map interface, with predictable iteration order.