Develop Reference

Only handling tree will expand but not tree selection in JTree - Java Swing

I am doing lazy loading for my app. I want a node to load only user click to it's icon. The point is i don't know that node have it's children or not.My temporary solution is to define a node having children then loading them based on selection event, i don't use tree will expand event for lazy loading. Is there any ways for me to just implement treeWillExpand event. You can reference in TreeWillExpanListener and TreeExpandEventDemo2.

// Have a tree with some unexpanded root items
// When an item is expanded, add some children
tree.addListener(new Tree.ExpandListener() {
public void nodeExpand(ExpandEvent event) {
// No children for the first node
if (!hasChildren(event.getItemId())) {
tree.setChildrenAllowed(event.getItemId(), false);
} else {
// Add a few new child nodes to the expanded node
tree.addItem(childId);
tree.setParent(childId, event.getItemId());
}
}
});
you can implement hasChildren to find the child based on tree node being expanded and then find child and add

Why does node selection not work properly after TreeModel reload?

I have a Swing application that uses a JTree. I want some of the nodes of the tree to be hidden, so I have implemented two DefaultTreeModels, one with every node and a filtered one with only the ones that should be displayed. The latter is set as the actual model.
At some points I must change the filtered nodes, and when I do, the items in the tree update properly, but their behavior is wrong. Nodes do not get highlighted when they are selected (even though they are indeed selected) and the user can no longer double-click to expand a node, they must click the little '+' button.
Below is a generalization of my code, two methods from my custom class that extends JTree.
updateFilter gets called when the filter needs to be updated.
populateFilteredNode recursively populates the root node of my filtered model. For simplicity, filteredRoot is a class member variable (of type DefaultMutableTreeNode) and is the root of the filtered model. fullModel and filteredModel are of type DefaultTreeModel
public void updateFilter() {
// Get current expansion state
ArrayList<Integer> expansionState = getExpansionState();
DefaultMutableTreeNode fullModelRoot = fullModel.getRoot();
// Remove existing nodes in the filtered model
while(filteredRoot.getChildCount() > 0) {
filteredModel.removeNodeFromParent(filteredRoot.getFirstChild());
}
populateFilteredNode(fullModelRoot, filteredRoot);
// Repaint tree and restore expansion state
repaint();
setExpansionState(expansionState);
}
private void populateFilteredNode(DefaultMutableTreeNode fullNode, DefaultMutableTreeNode filteredNode) {
int index = 0;
for(int n = 0; n < fullNode.getChildCount(); n++) {
DefaultMutableTreeNode fullChildNode = fullNode.getChildAt(n);
// Show the item and its children if one of many cases is true
if(shouldShowItem(fullChildNode.getItem())) {
DefaultMutableTreeNode filteredChildNode = fullChildNode.clone();
filteredModel.insertNodeInto(filteredChildNode, filteredNode, index++);
populateFilteredNode(fullChildNode, filteredChildNode);
}
}
}
If anyone has a similar experience or knows why the selected node will not appear highlighted, please let me know. Or if there is a better way to accomplish filtering. Or if more code would help provide an answer.

I found something that works for my case, although it's quick and dirty and I don't necessarily understand why it works. This 12-year-old post on Code Ranch somehow got me headed in the right direction. I'm just posting it here in case anyone has a similar problem and it might be of help.
I save the selection path before making any changes to the table model, and then call this new function findNewSelectionPath after the changes were made. Below is a generalized version of the function (I use several custom classes so I did my best to make it look generically usable).
private TreePath findNewSelectionPath(TreePath oldSelectionPath) {
TreePath newSelectionPath = null;
if(oldSelectionPath != null) {
Object[] oldPathComponents = oldSelectionPath.getPath();
Object[] newPathComponents = new Object[oldPathComponents.length];
DefaultMutableTreeNode node = (DefaultMutableTreeNode) filteredModel.getRoot();
// Set the root
if(oldPathComponents[0].equals(node)) {
newPathComponents[0] = node;
}
// Set the rest of the path components
for(int n = 1; n < oldPathComponents.length; n++) {
for(int k = 0; k < node.getChildCount(); k++) {
if(oldPathComponents[n].equals(node.getChildAt(k))) {
newPathComponents[n] = node.getChildAt(k);
node = node.getChildAt(k);
break;
}
}
}
// Make sure that the last path component exists
if(newPathComponents[newPathComponents.length - 1] != null) {
newSelectionPath = new TreePath(newPathComponents);
}
}
return newSelectionPath;
}

java swt jface TreeViewer expanding from node

How can I expand the node to its root node?
So I have this method to expand its parent node recursively
private void expand( Object object ) {
if ( object.getParent() != null ) {
tree.setExpandedState( object.getParent(), true );
expand( object.getParent() );
}
}

Use the expandToLevel TreeViewer method:
viewer.expandToLevel(element, 1);
element can be your model element (the object your content provider provides) or it can be a TreePath. You may need to call setUseHashlookup(true) on the viewer to speed up element lookup.

Primefaces Tree: don't remove the node after drag and drop

Is it possible not to remove the node from the original PrimeFacesTree after dragging it? The default behaviour is that a node that was dragged and dropped in another place is removed. Can i prevent that from happening?
I'm using Primefaces 4.0

There isn't any premade attribute to duplicate node on dropEvent.
The solution is to add a listener to your <p:tree> element :
<p:tree listener="#{managingBean.onDragDrop}" />
Then you need to re-create node on initial location by duplicating it in your backbean method :
public void onDragDrop(TreeDragDropEvent event) {
TreeNode dragNode = event.getDragNode();
TreeNode dropNode = event.getDropNode();
int dropIndex = event.getDropIndex();
// Logic to repopulate initial Tree element
}
And don't forget to re-draw your tree

Expanding Wickets TreeTable nodes when initializing a tree

I'm pretty new to wicket and I'm trying to create a simple wicket tree that holds information about mailinglists. This mailinglist is related to a certain letter.
MailingListDto 1
User 1
User 2
MailingListDto 2
User 3
User 4
If we are editing an existing letter, the mailinglists related to that letter are fetched into mailingListCollection and the corresponding nodes on the tree should be selected and expanded. For some reason I don't seem to get this workin.
The selected and expanded nodes do not show as selected nor expanded in the UI, but if I go through the selected nodes programmatically for example in onAfterRender() and log the selected and expanded values, the nodes are expanded and selected.
tree = new TreeTable("treeTable", treeModel, treeColumns) {
#Override
public void onBeforeRender() {
super.onBeforeRender();
if (!mailingListCollection.isEmpty()) {
for (MailingListDto mailingList : mailingListCollection) {
tree.getTreeState().expandNode(mailingList);
tree.getTreeState().selectNode(mailingList, true);
}
}
tree.updateTree();
}
#Override
protected void onAfterRender() {
super.onAfterRender();
if (LOG.isDebugEnabled()) {
LOG.debug("onAfterRender: " + tree.getTreeState().getSelectedNodes().size());
for (Object obj : tree.getTreeState().getSelectedNodes()) {
LOG.debug(tree.getTreeState().isNodeSelected(obj) + " " + tree.getTreeState().isNodeExpanded(obj));
}
}
}
};
tree.setRootLess(true);
tree.getTreeState().setAllowSelectMultiple(true);
add(tree);

To expand only the root node of your tree:
Object rootObj = myTree.getModelObject().getRoot();
myTree.getTreeState().expandNode(rootObj);
To expand also the first child of the root node add the following line to the previous ones:
myTree.getTreeState().expandNode(myTree.getModelObject().getChild(rootObj, 0));
Note that you have to expand all parent nodes of the "target" node otherwise on the screen the target node will be hidden because of a collapsed parent.

wicket 1.5.10
wicket 6
Look at source code. In class FooExpansion.java is a method expandAll().
FooExpansion.java is used in private class FooExpansionModel.java is used in AdvancedTreePage.java.
So a simple solution, when init your tree (in AdvancedTreePage.java), could be:
FooExansionModel model = new FooExpansionModell()
tree = createTree(provider, model);
((FooExpansion)model.getObject()).expandAll();