How can i loop over Tree in ZK? - zk

Question

I try to get the values of the ZK Tree from this example. But i not get the all childrens value...what i tried:
List<Treechildren> treeChildren = new ArrayList<>();
List<Label> labelList = new ArrayList<>();
List<Label> childs = new ArrayList<>();
tree.getChildren().forEach(component -> {
if(component instanceof Treechildren){
treeChildren.add((Treechildren) component);
}
});
List<Treeitem> treeItems = new ArrayList<>();
treeChildren.forEach(treechildren ->{
treeItems.addAll(treechildren.getChildren());
});
List<Treechildren> children = new ArrayList<>();
treeItems.forEach(treeitem -> {
System.err.println("treeitem: " + treeitem);
if (treeitem.getChildren().size() > 1) {
treeitem.getChildren().forEach(child -> {
if(child instanceof Treechildren){
children.add((Treechildren) child);
} else {
List<Treecell> tcList = new ArrayList<>();
child.getChildren().forEach(component -> {
if(component instanceof Treecell) {
tcList.add((Treecell) component);
}
});
List<Hlayout> hlList = new ArrayList<>();
tcList.forEach(treecell ->{
System.err.println("treecell" + treecell);
hlList.addAll(treecell.getChildren());
});
hlList.forEach(hlayout -> {
childs.addAll(hlayout.getChildren());
});
}
});
}else {
List<Treerow> tr = new ArrayList<>();
treeitem.getChildren().forEach(component -> {
if (component instanceof Treerow) {
tr.add((Treerow) component);
} else {
}
});
List<Treecell> TC = new ArrayList<>();
tr.forEach(treerow -> {
TC.addAll(treerow.getChildren());
});
List<Hlayout> HL = new ArrayList<>();
TC.forEach(treecell -> {
HL.addAll(treecell.getChildren());
});
HL.forEach(hlayout -> labelList.addAll(hlayout.getChildren()));
}
});
labelList.forEach(label -> System.err.println("label: " + label.getValue()));
childs.forEach(label -> System.err.println("childs: " + label.getValue()));
}
But i not get the whole tree labels....the aim is to save the tree to database when i push the submit button.

Answer 1

Since you did not post your tree, I can only guess how it looks. But I tried to at least understand your code and found a potential bug: In line 21 handle the case where tree nodes have sub nodes. You add the Treechildren to children, but never do anything with it. So you loop will stop at the first level.
First of all, I would recommend using the special methods for trees and their components:
Tree: getTreechildren()
Treeitem: getTree(), getTreerow() and getTreechildren()
Treerow: getTree() and getLinkedTreechildren()
These help you to get rid of all the casting and instanceof checks. Furthermore, you can specify the type of children when calling getChildren():
List<Treecell> cells = row.<Treecell> getChildren()
Now you don't have to cast, but to be careful that all children are of the same type.
Finally, I refactored your code to understand it:
// Find all items in the tree, level by level
List<Treeitem> items = new ArrayList<>(tree.getTreechildren().getChildren());
List<Treeitem> itemsTemp = new ArrayList<>(tree.getTreechildren().getChildren());
while (!itemsTemp.isEmpty())
{
Treeitem nextChild = itemsTemp.remove(0);
if (nextChild.getTreechildren() != null)
{
items.addAll(nextChild.getTreechildren().getChildren());
itemsTemp.addAll(nextChild.getTreechildren().getChildren());
}
}
// convert item -> row -> cells -> hlayouts -> children
List<Component> children = items.stream()
.map(Treeitem::getTreerow)
.filter(Objects::nonNull)
.flatMap(row -> row.<Treecell> getChildren().stream())
.flatMap(cell -> cell.<Hlayout> getChildren().stream())
.flatMap(hlayout -> hlayout.getChildren().stream())
.collect(Collectors.toList());
// // without streams
// List<Component> children = new ArrayList<>();
// for (Treeitem item : items)
// {
// if (item.getTreerow() != null)
// {
// for (Treecell cell : item.getTreerow().<Treecell> getChildren())
// {
// for (Hlayout hlayout : cell.<Hlayout> getChildren())
// {
// children.addAll(hlayout.getChildren());
// }
// }
// }
// }
You can see that in the while loop, I looked at the tree's children on the first level, then at their children, that at those children's children, and so on. Then I used the methods mentioned above to find the components of each tree node.
Again, I do not know how your tree looks, so I do not know whether this works for you. Maybe you could post a small example.