GetAllSets return out off memory

Question

Hi,
a while ago i posted a topic about getting all the possibele combinations between treenode s
the thread can be found here
http://forum.java.sun.com/thread.jsp?forum=426&thread=500849 - March 11, 2004
but now i've encountered when the tree becomes large that i get an out off memory problem on the set
is there some way to avoid that ?
the code used to read the tree and fill up the set is
public static Set getAllSets(TreeModel model, Object node) {
    Set result = new HashSet();
    int child = (int) Math.pow(2, model.getChildCount(node));
    for (int i = 0; i < child; i++)
    { // foreach powerset of the immediate children
      Set set = new HashSet();
      for (int j = 0; j < model.getChildCount(node); j++) {
        if ( (i & 1 << j) != 0) {
          set.add(getAllSets(model, model.getChild(node, j)));
      result.addAll(magicProduct(set));
   for (Iterator k = result.iterator(); k.hasNext(); ) {
      ( (Set) k.next()).add(node);
    //  System.out.println( ""+result .toString() );
    return result;
  public static final Set magicProduct(Set sets) {
    Set result = new HashSet();
    result.add(new HashSet());
    for (Iterator i = sets.iterator(); i.hasNext(); ) {
      result = magicProduct(result, (Set) i.next());
    return result;
[\code]
hope somebody can help

Answer 1

A less rigorous solution is to set your maximum heap size higher (if you have the space). For example:
java -Xmx=256M args...[i]
But, yes, using disk or a more efficient algorithm might be a better solution.