Hashtable elements to vector

[Meir Yan]

Hashtable elements to vector

Hello all
I have Hashtable object that contains 3 elements
something like this :

    
Hashtable  myHash = new Hashtable();
myHash.put("1","a");
myHash.put("1","b");
myHash.put("1","c");
 
now i like to set 3 elements in a vector that will contain each element
of the hashtable so it look like :
 

vec[0] >Hashtable("1","a");
vec[0] >Hashtable("2","b");
vec[0] >Hashtable("3","c");
 

i find it hard to understand why i can't set it right .. i tried to do :

 
Vector vec = new Vector(myHash.size());
Enumeration vecEnum = vec.elements();
while(vecEnum.hasMoreElements()){
vec.add(new Hashtable().put(????.?????)); // what to put here if any?
....
....
}
 

[Brian Mozhdehi]

Hi.....you want to add the HashTable objects to the Vector or the contents of the HashTable to a Vector?

[Garrett Rowe]

So what you want is for each element of the Vector to contain a Hashtable with a single element? What are you trying to achieve exactly by dong that?

BTW: Why are you using Vector and Hashtable instead of the more highly recomended ArrayList (or LinkedList) and HashMap

[Meir Yan]

yep single element in the hashtable ( dont ask why .. work )
have to use vector ( also work )
can it be done?

[Garrett Rowe]

How about :

Set elements = myHash.entrySet();
Iterator elementIter = elements.iterator();
while (elementIter.hasNext())
{
   Map.Entry element = elementIter.next();
   vec.add(Collections.singletonMap(element.getKey(), element.getValue()));
}

[Meir Yan]

it seams that Collections.singletonMap makes me some problems
(some iternal application things ) is there aproblem to make
it pure Map(key,value)
so when i debug it will see in the vector elemnts they contain pure hashtables
can it be done ?

[Garrett Rowe]

Set elements = myHash.entrySet();
Iterator elementIter = elements.iterator();
 
while (elementIter.hasNext())
{   
   Map.Entry element = elementIter.next();
   vec.add(new Hashtable().put(element.getKey(), element.getValue()));
}

[Meir Yan]

i dont know why put it fill the vector with empty values , not hashtable

[Garrett Rowe]

I see what's happening. The put() method returns the value that was just added to the Hashtable. You'll have to instantiate the Hashtable and populate it on separate lines.

Set elements = myHash.entrySet();
Iterator elementIter = elements.iterator();
 
while (elementIter.hasNext())
{   
   Map.Entry element = elementIter.next();
   Map temp = new Hashtable();
   temp.put(element.getKey(), element.getValue());
   vec.add(temp);
}

[ August 23, 2006: Message edited by: Garrett Rowe ]