Sorting problem in HashTable

Question

my problem is i have to parsed these values

Cijfercode 
Crypto 
Doorlopr 
Kruizword 
Woordzoker
Zweeds

from an xml file.but in xml they are in the alphabetical order same as above.but while using hashtable to retrive values (these values are not keys of this hashtable)it becomes the order

Cijfercode
Doorloper
Woordzoker
Zweeds
Kruizword
Crypto

why is is happening?

aioobe · Accepted Answer · 2011-07-28 07:07:39Z

7

You need to use LinkedHashMap to maintain the order in which the elements where inserted, (or a TreeMap if you need some custom ordering, such as alphabetical, regardless of insertion order).

A HashTable does not preserve any order. Just like Set it's an unordered data structure.

answered Jul 28, 2011 at 7:07

aioobe

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7 Comments

divz Over a year ago

ok but firsly values are added alphabetical order in the hashtable.

aioobe Over a year ago

yep. Unfortunately that doesn't matter. It should work as you expect if you use a LinkedHashMap.

divz Over a year ago

but retriving from hashtable order changes.

amal Over a year ago

so ? If you are looking at retrieving elements in the same order it was inserted , you shouldnt be using an unorderded data structure , should you ?

legendofawesomeness Over a year ago

LinkedHashMap maintains the order of the elements same as they we inserted; if that is what you want then use LinkedHashMap. If you want to get natural ordering of elements, say alphabetically, then TreeMap should be used.

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legendofawesomeness · Accepted Answer · 2011-07-28 07:08:45Z

0

HashTable and HashMap both do not guarantee the ordering of it's elements. You should use TreeMap for such purposes.

answered Jul 28, 2011 at 7:08

legendofawesomeness

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1 Comment

divz Over a year ago

Hi every one. i got a solution for sorting the hashtable elements .Here is the solution java.util.Vector vec =new java.util.Vector(hashtableList.keySet()); Collections.sort(vec);

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