asked on

How do i use an iterator to get data from a hashtable?

I am having a bit of trouble understanding collections in Java and how they relate to iterators.

I have a hashtable - ResTable(res, value); and i need to use an iterator to go through each element in my hash table and copy the value res into a string array and also copy value into a separate int array. How do i go about defining the iterator for my hashtable?

private static void CopyToArray(){

// I know that i have to define my collection by something like...
Collection myCollection = .....; // do i assign ResTable equal to mycollection? How??
//Then i can say...
Iterator i = myCollection.iterator();
while (i.hasNext()){
System.out.println(i.next());
// Do what i need to to convert data from hash table to array
//Cast datatype etc
}
}

Any seggestion in either code format, psuedocode or basic english would be much appreciated.

Nutty

rjackman

it seems that u want to get the values without knowing the keys in the table then u can do the following
Set keys = ResTable.keySet();
for(Iterator itr = keys.iterator();itr.hasNext();)
{
String key = (String)itr.next();
System.our.println("Keys---->"+key);
System.out.println("Value--->"+ResTable.get(key));
}

cheers
RJ

kotan

You don't need to assign ResTable to Collection. Because it is already a Collection.

To extract the keys of ResTable into String array,
String[] strArr = (String[]) ResTable.keySet().toArray(new String[0]);

For values, You can only copy into Integer object but not int primitive type.

Integer[] iArr = (Integer[]) ResTable.values().toArray(new Integer[0]);

ASKER CERTIFIED SOLUTION

jose_tijo

membership

This solution is only available to members.

To access this solution, you must be a member of Experts Exchange.

Start Free Trial

vemul

No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

- points to jose_tijo

Please leave any comments here within the
next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !

vemul
Cleanup Volunteer

Computer101

Comment from expert accepted as answer

Computer101
E-E Admin