hashtable values reordered

Question

I have a hashtable, which contains strings for example, when I use put method as below

 hashtable.put("1","A");
 hashtable.put("1","B");
 hashtable.put("1","C");
 hashtable.put("1","D");
 hashtable.put("1","E");

Then when I try to print it back it doesn't print in same order, Any one knows why would something like this happen?

 Collection c = ht.values();
 Iterator itr = c.iterator();
 while(itr.hasNext())
 System.out.println(itr.next());

Thanks Max

Answer 1

A Hashtable does not guarantee any kind of ordering.

If you want to preserve insertion order, use a LinkedHashMap . However, the contract is slightly different than a Hashtable in that it allows null elements.

Answer 2

如果要按顺序打印项目，则应使用LinkedHashMap 。

Answer 3

That is simply the property of a hash table -- it makes no guarantee about ordering. Do you want to use a LinkedHashMap instead?

Answer 4

HashTable不会保持顺序，它将随机打印，您应该使用LinkedHashMap。您可以像使用HashMap一样使用LinkedHashMap。只需将LinkedHashMap替换为HashMap.LinkedHashMap会保持输入数据的顺序。