# Re: Problems instantiating a Vector<Vector<Integer>>

From:
"hiwa" <HGA03630@nifty.ne.jp>
Newsgroups:
comp.lang.java.programmer
Date:
31 Oct 2006 17:38:09 -0800
Message-ID:
the.real.doctor.zoidberg@gmail.com wrote:

Hi,

i'm having some problems with instantiating a vector of vectors of
integers.

From the debugger i can see that all of the vector elements (which are

vectors) are null. But i am unable to point them to a *new* vector
because i can't iterate them.

// i can create the "main" vector, but i still need to instantiate all
100 Vectors of Integers
Vector<Vector<Integer>> skips = new Vector<Vector<Integer>>(100);

// the problem with this is that hasMoreElements returns false
Enumeration it = skips.elements();
if (it.hasMoreElements())
elem = (Vector<Integer>)it.nextElement();

// also suffers from the same problem... it says that it has no
elements
ListIterator<Vector<Integer>> it = skips.listIterator();
if (it.hasNext())
elem = new Vector<Integer>();

How do i fix this?

If you haven't instantiated it, it should be null.
It is only natural.
Try this:
-----------------------------------------------------------------
import java.util.*;

public class VecVec{

public static void main(String[] args){
Vector<Vector<Integer>> vvi;
Vector<Integer> elem = null;

vvi = new Vector<Vector<Integer>>();
for (int i = 0; i < 100; ++i){
}

Enumeration<Vector<Integer>> it = vvi.elements();
if (it.hasMoreElements()){
elem = (Vector<Integer>)it.nextElement();
}
System.out.println(elem != null);

elem = null;
ListIterator<Vector<Integer>> lit = vvi.listIterator();
if (lit.hasNext()){
elem = (Vector<Integer>)lit.next();
}
System.out.println(elem != null);
}

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