ArrayList clears when placed in HashMap

Question

I have a series of ArrayLists (argValues), to be used as the values in a HashMap. They are not empty when they are placed in the table, but when I try to get one of them out, the ArrayList that is returned is empty. Here is the part of my code that has the problem. I'm parsing an XML file beforehand (doc_cmd is the Document into which the XML was parsed):
           NodeList nl_cmd = doc_cmd.getElementsByTagName("RFSW_CMD_PKT");
           if (doc_cmd != null) {
               for(int i = 0; i < nl_cmd.getLength(); i++) {
                    if (!nl_cmd.item(i).getNodeName().equals("#text")) {
                        String key = nl_cmd.item(i).getAttributes().getNamedItem("NAME").getNodeValue();
                        //   System.out.println(key);
                        Element currentCmd = (Element) nl_cmd.item(i);
                        NodeList nlChildren = currentCmd.getChildNodes();
                        ArrayList argValues = new ArrayList();
                        for (int j = 0; j<nlChildren.getLength(); j++) {
                            if (!nlChildren.item(j).getNodeName().equals("#text")) {
                                nodeName = nlChildren.item(j).getNodeName();
                                if (!nodeName.equals("BITFIELD") && !nodeName.equals("UNION"))
                                    argName = nlChildren.item(j).getAttributes().getNamedItem("NAME").getNodeValue();
                                else
                                    argName = "";
                                value = nodeName + "_" + argName;
                                argValues.add(value);
                        // THIS IS WHERE THE PROBLEM IS
                        System.out.println("ARGVALUES SIZE = " + argValues.size());
                        hashcmds.put(key, argValues);
                        argValues.clear();
                        ArrayList yo = (ArrayList)hashcmds.get(key);
                        System.out.println("SIZE = " + yo.size());

Answer 1

Note that you're calling the clear method on the
object you've inserted, not a copy of it. You should
clone() itIn this case I there is no point in cloning the ArrayList because it goes out of scope. He isn't resuing it and there was never a reason to clear it anyway. The solution is to just not clear the ArrayList.
If one were attempting to reuse it in that manner, cloning an ArrayList and clearing it to use again is less efficient than just creating a new one and letting the old one go out of scope.
The steps required to fill clone and reuse.
1. create new ArrayList
2. copy references
3. clear entries
4. insert n refereneces
The steps required to just create new
1. create new ArrayList
2. insert n references
By clearing the ArrayList here, you are just doing more work.