So i'm trying to make a copy of a vector....

Question

... and it seems that i'm doing something wrong. I need to make a copy of the original vector because I need to clear it before the return statement(which returns a vector) so i'll have a clear vector to work with once the method is called again. I figure i'll just return the copy, but everytime I run my program its output isn't right unless I specifically return the first vector.
I've declared
Vector<Widget> original = new Vector<Widget>();
Vector<Widget> clone = new Vector<Widget>();at the beginning of the class, and put the following at the inside the method of interest, at the end (after the original was filled with elements):
clone = original;
original.clear();
return clone;that didn't work, so I tried this:
clone = (Vector<Widget>) original.clone();
original.clear();
return clone;That didn't work either. Can someone explain to me how this works and what i'm doing wrong?
Thanks.

Answer 1

I apologize... i'm aware that a few students in my class visit this site, and don't want them copying my code.
The code i've posted above is actually modified (changed the variable names), in an attempt to stop this.
Here is the more info:
What i'm trying to do is traverse a binary tree recursively for a (node.data).number that matches the argument the method takes in. The method is supposed to start at the root and add every node's data on the way to (and including) that particular node's data in to a vector, then return that vector.
The nodes have the parameters: (data, parentNode,leftNode, and rightNode) where the leftNode and rightNodes represent the children of the node. The "data" parameter is an object with several other parameters... the only one of interest being "number". The traveler2 variable represents a node that I initialized (as class variables) to the root and will be using to traverse the tree. The Widget vectors clone and original have already been initialized in the class (class variables). The compareTo method was defined in another class, and compares an integer object with a node's data's number, to see if it's equal or not.
public Vector<Widget> route(int widgetNumber)
          Integer wNumber = widgetNumber;
          clone.clear();
          if(wNumber.compareTo((traveler2.data).getNumber()) == 0 && wNumber!= null && traveler2.data != null)
               original.add(traveler2.data);
               traveler2 = root;
          else if(wNumber.compareTo((traveler2.data).getNumber()) == -1 && wNumber!= null && traveler2.data != null)
               original.add(traveler2.data);
               if(traveler2.leftNode == null)
                    traveler2 = root;
               else
                    traveler2 = traveler2.leftNode;
                    route(widgetNumber);
          else
               original.add(traveler2.data);
               if(traveler2.rightNode == null)
                    traveler2 = root;
               else
                    traveler2 = traveler2.rightNode;
                    route(widgetNumber);
          for(int i = 0; i < original.size(); i++)
              Widget fromOriginal = original.get(i);
              clone.add(new Widget(fromOriginal.getNumber(), fromOriginal.getW1(), fromOriginal.getW2(), fromOriginal.getW3(), fromOriginal.getW4(), fromOriginal.getW5()));
          original.clear();
          return clone;
     }The teacher has supplied an application that illustrates the path created when one runs the method. However, no path appears. No console errors either. I'm lost. If I were to take out the "original.clear();" line, and return original instead of clone, the method would work. However when it is called again, there is no way the path can be cleared to create a new one, thus providing an incorrect path (anytime other than the first time it is called).
Please help?
Thanks.
Edited by: klawson88 on Mar 12, 2009 10:24 PM
Edited by: klawson88 on Mar 12, 2009 10:26 PM