Question

im tryind to build an Vaadin tree from an XML file(MSDL), im stuck at adding child items to my tree. So far i can read from my XML file and display the the tags/info i want but i cant make an Hierarchical strukture out of it , e.g :

i have an XML file with some information about Planets and their moons and the galaxy they are in :

Milky Way
 -Sunsystem
  -Earth
   -"Moon"
  -Mars
    -Phobos
    -Deimos
  -Saturn
    -Titan
    -Tethys
Pinwheel Galaxy
 -somesystem
   -weirdPlanet1
     -moon1
     -moon2
   -weirdPlanet2
     -moon1
     -moon2

now i want to have the same strukture in my vaadin tree. i have tryed lots of things but the result was always the same : some null values where added to the tree of i could see only the galaxys but i couldnt expand them or i could see a tree with all the infos but there whee no strukture at all all planets / moons where just listed :/

Answer 1

I’m pretty sure this doesn’t have anything to do with the Tree itself. Instead of adding the data directly to the Tree, you can try this:

1. Parse the XML data into a HierarchicalContainer
2. Iterate through the HierarchicalContainer with the sample code below and verify that it’s identical to your XML file structure
3. Bind the data container to the tree by calling Tree.setContainerDataSource(Container)

Sample code to iterate through a HierarchicalContainer:

void iterateContainer() {
    for(Object rootItemId : myContainer.rootItemIds()) {
        Item rootItem = myContainer.getItem(rootItemId);
        System.out.println(rootItem.getItemProperty(myLabelProperty).getValue());

        iterateChildren(rootItemId, 1);
    }
}

void iterateChildren(Object parentItemId, int indent) {

    for(Object childItemId : myContainer.getChildren(parentItemId)) {
        Item childItem = myContainer.getItem(childItemId);

        for(int i = 0; i < indent; i++) {
            System.out.print(" ");
        }
        System.out.println(childItem.getItemProperty(myLabelProperty).getValue());

        if(myContainer.hasChildren(childItemId)) {
            iterateChildren(childItemId, indent+1);
        }
    }

}

This is just some untested QnD code, but this should help you to iterate through the container.

edit: Just noticed that my answer could have been (partially) a stupid solution, since Tree already utilizes HierarchicalContainer. You can initialize myContainer HierarchicalContainer myContainer = (HierarchicalContainer) myTree.getContainerDataSource(); and use the code above.

edit2: And if the structure isn’t identical, see where it goes wrong and let the debugger do the rest .. 🙂