HashMap的迭代器究竟意味着什么，它的失效速度很快，而HashTable的枚举器不是？ [英] What do you exactly mean by HashMap's iterator is fail-fast and HashTable's enumerator isn't?

问题描述

我正在查找这两个班级之间的差异，这一点出现在很多答案中，这个博客是来源：
http://javarevisited.blogspot.com/2010/10/difference-between-hashmap-and.html

但是我并不完全明白。
有人可以详细说明这一点吗？也许有例子吗？

感谢您的支持！

快速失败意味着当您在迭代时尝试修改内容时，它会失败并抛出ConcurrentModificationException。

  Set keys = hashMap.keySet（）; 
 for（Object key：keys）{
 hashMap.put（someObject，someValue）; //它会在这里抛出ConcurrentModificationException 
 
 
 
 
对于HashTable枚举：
 枚举键= hashTable.keys（）; 
 while（keys.hasMoreElements（））{
 hashTable.put（someKey，someValue）; //这是好的
} 
  
 
I was looking up the difference between the two classes and this point came up in a lot of the answers with this blog being the source: 
http://javarevisited.blogspot.com/2010/10/difference-between-hashmap-and.html

However I don't completely get it.
Can someone elaborate this? Perhaps with an example?

Thanks for looking in!
解决方案
Fail-fast means when you try to modify the content when you are iterating thru it, it will fail and throw ConcurrentModificationException.
Set keys = hashMap.keySet();
for (Object key : keys) {
    hashMap.put(someObject, someValue); //it will throw the ConcurrentModificationException here
} 
For HashTable enumeration:
 Enumeration keys = hashTable.keys();
 while (keys.hasMoreElements()) {
          hashTable.put(someKey, someValue);  //this is ok
    }


                        
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