Develop Reference

Getting a Boolean value JAVAFX

I have a group of nodes within a GridPane and have some listeners adding and removing those nodes from the GridPane.
I was wondering if there is a way for me to create a get method(Boolean) or such to test if the nodes are currently in the GridPane or not.
I want to enable the button when the nodes aren't in the gridpane aka false.
Any help/thoughts appreciated!

That's how you can check for the presence of a node:
gridpane.getChildren().contains(yourNode);

You can check if the parent of the Node node that you want to check is the GridPane. This should be a bit faster than using the child list, since it does not require iterating through the child list:
node.getParent() == gridPane
You can also use bindings to enable/disable the button (assuming there is a single node that decides, if the Button should be enabled or disabled)
button.disableProperty().bind(node.parentProperty().isEqualTo(gridPane));

Duplicating a JavaFx group node loaded from FXML in run time

I am trying duplicate a group node which i designed in scene builder. Then add the same to a vertical box below to the same node.
The group node contains a label, text field and a button. When i click the button it should add a duplicate group node below
I tried using
FXCollections.copy(dest, src);
by passing the observable list into it. But the vbox says duplicate id.
If there are any good ideas. pls let me know.

Building a Complete Check Box Node Tree

My objective is to build a check box node tree with the following features .
Nodes :
There will be 2 types of nodes all over the tree .
1 . Parent Nodes
2 . Child Nodes
All the nodes are check box nodes .
The parent nodes need to have an additional folder like icon , in addition to the check box.
And all the check boxes must be editable
More than one check box must be checkable at a time .
What is the best possible approach that i can take ?

Looks similar to this Stack Overflow result:
JTree with checkboxes
Which refers to this example: http://www.java2s.com/Code/Java/Swing-JFC/CheckBoxNodeTreeSample.htm
In this latter example, change nonLeafRenderer to return your new component (a folder with a checkbox, possibly in a JPanel.)

If you want a ready to go component you can use CheckBoxTree from Jide-oss.

Add 'expand' button to JTree node that has no children?

I'd like to add the 'expand' button to my JTree's nodes to indicate that they are expandable. The catch is that they have no children until the user clicks on them (due to processing that happens in the background).
Is there any way I can set a node as a parent or having children without it actually having children?
Thanks

It's possible using your own DefaultMutableTreeNode implementation overriding isLeaf():
Returns true if this node has no children.
Swing Tutorial: JTree explains it under 4.1 Dynamic Tree.

Have a fake child/child count and replace it with real children using TreeWillExpandListener

Creating Dynamic JTrees (Controlling Root Node Visibility)

I have a question about how to dynamically generate JTrees. Is there a way to set the Root Node invisible without making its children invisible too? I have tried to do the following but it shows all nodes as invisible. Keep in mind that I want to add and remove children of the Root Node at any point in time. I've added comments so you can follow what I intend to do. Let me know if they are doing something I dont need, as I am new to JTrees and don't know the conventions. I would also like to be able to select multiple children for the listener.
DefaultMutableTreeNode rootNode;
rootNode = new DefaultMutableTreeNode(); //I want this invisible.
DefaultTreeModel treeModel = new DefaultTreeModel(rootNode);
JTree tree = new JTree(treeModel);
treeModel.addTreeModelListener(this);
tree.setRootVisible(false); // Sets everything invisible
tree.setEditable(true); //makes tree dynamic
tree.setShowsRootHandles(true); //supposedly allows you to see the children of the nodes.
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
//I would like the line above to be multi-select; however, this doesn't seem to be an option.
DefaultMutableTreeNode table = new DefaultMutableTreeNode( "table1");
rootNode.add(book);
DefaultMutableTreeNode value = new DefaultMutableTreeNode( "value");
table.add(value);
In the above example. Nothing is shown and when I remove the "tree.setRootVisible(false)" everything is visible including the node.

A very late answer, but I have just had the same problem.
Ensure to expand your root node, so that its children become visible :
yourTree.expandPath(new TreePath(root.getPath()))

I'd say the difference between the code in the question and in the TreeDemo is that the tree demo creates and adds all its nodes before creating the actual tree. If the nodes are to be added dynamically (after the tree is created) it should be done through the TreeModel. Otherwise no events saying the tree has changed will be generated. At least that is what the tutorial seems to say about editing the node's "content", might be the same issue:
Note that although DefaultMutableTreeNode has methods for changing a
node's content, changes should go through the DefaultTreeModel cover
methods. Otherwise, the tree model events would not be generated, and
listeners such as the tree would not know about the updates.
Someone's solution

Works fine for me. I based my tests on the TreeDemo from the Swing tutorial on How to Use Trees. Compare your code with the tutorial code to see what the difference is.

A very late answer also, I'm a java beginner and had the same problem so it may help.
setRootVisible(false) also hides all nodes for me so I added setShowsRootHandles(true) to show all nodes :
tree.setRootVisible(false);
tree.setShowsRootHandles(true)
I hope it helps !
https://docs.oracle.com/javase/tutorial/uiswing/components/tree.html#display