Stephan,
can you put that to the wiki ?
On 7/13/06, stephan opitz <[EMAIL PROTECTED]> wrote:
thx
2006/7/13, Gary VanMatre <[EMAIL PROTECTED]>:
> >From: "stephan opitz" <[EMAIL PROTECTED]>
> >
> > problem is the structure.
> >
> > if i have an object containing an id and a parentId (which is null, or
> > linking to another object -> the parent one)
> >
> > if i get a list from db how is it possible to build up the structure
> > for the tree2
> >
> > i tried hashmap or recursive algorithm, but nothing with much success...
> >
> > any ideas
> >
>
> You might consider the following code snippet.
>
>
> public class TreeBacker {
>
> public TreeNode findNode(TreeNode root, Integer sarg) {
> Integer id = root.getDescription() == null ? null : new
Integer(root.getDescription());
> if (compare(id, sarg) == 0) {
> return root;
> }
> Iterator ci = root.getChildren().iterator();
> while (ci.hasNext()) {
> TreeNode found = findNode((TreeNode) ci.next(), sarg);
> if (found != null)
> return found;
> }
>
> return null;
> }
>
>
> public TreeNode getTreeData() {
>
> TreeNode root = new TreeNodeBase("root", null, false);
> TreeNode current = root; // current root
>
> Collection dbRows = getDBRows();
> Iterator di = dbRows.iterator();
> while (di.hasNext()) {
> MyVO vo = (MyVO) di.next();
>
> Integer id = current.getDescription() == null ? null : new
Integer(current.getDescription());
> int order = compare(id, vo.getParent());
>
> if (order != 0) {
> current = findNode(root, vo.getParent());
> // if current is null you have an orphaned node
> }
>
> String type = vo.getParent() == null ? null :
vo.getParent().toString();
> String desc = vo.getId() == null ? null : vo.getId().toString();
>
> current.getChildren().add(new TreeNodeBase(type, desc, false));
> }
>
> return root;
> }
>
>
>
>
> public Collection getDBRows() {
>
> // select parent, id from table order by parent, id
>
> // null, 1
> // null, 2
> // null, 3
> // 1, 4
> // 1, 5
> // 2, 6
> // 2, 7
> // 3, 8
> // 3, 9
> // 9, 10
> // 9, 11
>
> Set sortedList = new TreeSet();
> sortedList.add(new MyVO(null, new Integer(1)));
> sortedList.add(new MyVO(new Integer(1), new Integer(4)));
> sortedList.add(new MyVO(new Integer(1), new Integer(5)));
>
> sortedList.add(new MyVO(null, new Integer(2)));
> sortedList.add(new MyVO(new Integer(2), new Integer(6)));
> sortedList.add(new MyVO(new Integer(2), new Integer(7)));
>
> sortedList.add(new MyVO(null, new Integer(3)));
> sortedList.add(new MyVO(new Integer(3), new Integer(8)));
> sortedList.add(new MyVO(new Integer(3), new Integer(9)));
>
> sortedList.add(new MyVO(new Integer(9), new Integer(10)));
> sortedList.add(new MyVO(new Integer(9), new Integer(11)));
>
>
> return sortedList;
> }
>
> class MyVO implements Comparable {
>
>
> private Integer parent = null;
> private Integer id = null;
>
> public MyVO(Integer parent, Integer id) {
> this.parent = parent;
> this.id = id;
> }
> public Integer getId() {
> return id;
> }
> public void setId(Integer id) {
> this.id = id;
> }
> public Integer getParent() {
> return parent;
> }
> public void setParent(Integer parent) {
> this.parent = parent;
> }
>
>
> public int compareTo(Object obj) {
>
> MyVO vo = (MyVO) obj;
> int order = compare(parent, vo.parent);
> if (order == 0)
> order = compare(id, vo.id);
>
> return order;
> }
>
> }
>
>
> public static int compare(Integer col1, Integer col2) {
>
> if ((col1 == null) && (col2 == null))
> return 0;
> else if ((col1 == null) && (col2 != null))
> return -1;
> else if ((col2 == null) && (col1 != null))
> return 1;
> else
> return ((Comparable) col1).compareTo(col2);
> }
>
>
>
> public static void main(String[] args) {
> TreeBacker backer = new TreeBacker();
> TreeNode root = backer.getTreeData();
>
> }
>
>
> }
>
>
> > stephan
>
> Gary
>
--
Matthias Wessendorf
further stuff:
blog: http://jroller.com/page/mwessendorf
mail: mwessendorf-at-gmail-dot-com
