Compound JTree Node allowing events to pass through to objects underneath
I went through the answer by #Jakub Zaverka ,which was pretty lucid.But what I could not understand is where is the code to create tree nodes (JTree ,food,sports,colors).
Could someone explain how the nodes are created.
If I create a Node extending JPanel having a JButton and JLabel as fields ,can I set the node using the constructor of JTree which would be rendered and edited by the same custom renderer and editor.
The default JTree constructor "Returns a JTree with a sample model." To get the sample model, the constructor invokes the protected method getDefaultTreeModel(), which returns a sample model that is "Used primarily for beanbuilders to show something interesting." The values you see are contained in the source. A related example is seen here.
Related
For some specific purpose I am trying to manipulate UI by just accessing Swing/AWT component hierarchy, and I am stuck at JTree.
I have a JTree which is rendered using a custom TreeCellRenderer, and have JCheckBox in each node.
I am trying to obtain a specific JCheckBox object used to render a specific node, to programmatically change it's state, what I have is JTree Component object.
I couldn't find a way to get the JCheckBox component created to render a specific node.
If I keep calling Container.getComponents() recursively, I reach upto :
class javax.swing.JTree
class javax.swing.CellRendererPane
class javax.swing.tree.DefaultTreeCellRenderer
but these doen't seems to giving out components rendered by custom renderers.
As #JB-Nizet pointed out in comment, I solved my problem by updating custom model object using reflection.
Object modelObject = nodeToSelect.getUserObject();
Method method = modelObject.getClass().getMethod("setSelected", boolean.class);
method.invoke(modelObject,true);
What is meant by the word "Node" within context of JavaFx/FXML? If I search for this question, all I find are people using the term discussing something else, but no explanation. For example, this answer to the question: How do I open the JavaFX FileChooser from a controller class?:
For any node in your scene (for example, the root node; but any node
you have injected with #FXML will do), do
chooser.showOpenDialog(node.getScene().getWindow());
What would the node be, and how for that matter would I "inject it with #FXML"?
Before you understand what a Node is, it is also important to first of all understand what a Scene Graph is in JavaFX.
JavaFX applications consist of a Stage and a Scene or several scenes. The stage being the top-level container of your application. The Scene(s) on the other hand, contains all the content (User Interface elements) of your application (if your application has only one "page") or the content of one of the "pages" of your application, and exists in/on a stage. (To be clear here, by page I mean what the user interacts with, for instance, a login page.)
The Scene Graph is a graphical illustration of how all the stuff in your scene are laid out. This graph is represented in the form of a tree data structure.
A Node is an item in the scene graph.
I think this image explains this clearly.
Example of a Node is a Control, which is anything that can be manipulated by the user E.g., TextField, Button, TextArea
Photo Credit
A Node is the abstract superclass of the graphical elements the scenegraph are "made of".
Some examples of classes inheriting from Node:
TextField
AnchorPane
Canvas
Group
VBox
Button
Label
...
Injecting a Node with the FXMLLoader id done this way:
Create a field in the controller associated with the fxml with a appropriate type (i.e. any type the element you want to inject can be assigned to). This field must be accessible by the FXMLLoader which means it has to be public or annotated with the #FXML annotation.
Add the id attribute from the fxml namespace (most likely using the prefix fx) to the element in the fxml file that should be injected. The value of that attribute is the name of the field in the controller.
Example
fxml
....
<TextField fx:id="myTextField" ....>
....
Controller
....
#FXML
private TextField myTextField;
....
The FXMLLoader uses this information to assign the object it creates for that fxml element to the field before the controller's initialize method is called.
A full example/extendend tutorial including injection can be can be found here: https://docs.oracle.com/javase/8/javafx/fxml-tutorial/fxml_tutorial_intermediate.htm#JFXMG153
This is an old question, but it is answered abstractly. "What is a node?" and "in order to understand what is a node you must first understand what is a scene-graph". A node is the highest level abstract class from which nearly all that is graphically displayed in a GUI, is derived. Its super class is Object. In the image displayed by Ojonugwa Ochalifu there is one stage that contains one scene which contains several nodes that contain other nodes. The image shown of a GUI begs the question "How is this created?".
For general understanding here are the JavaDocs for Stage, Scene, and EventTarget.
In javafx doc Stage https://docs.oracle.com/javase/8/javafx/api/javafx/stage/Stage.html
and Scene https://docs.oracle.com/javase/8/javafx/api/javafx/scene/Scene.html
Both Stage and Scene inherit the same interface, EventTarget as well as Pane, and Control and a long list of classes. https://docs.oracle.com/javase/8/javafx/api/javafx/event/EventTarget.html
I also recommend looking at the source code for classes that you are using. It will help provide insight into the behavior of classes that inherit from node. For example, JavaFX documentation mentions that a bug could exist when displaying an Image. Ensuring that this bug does not occur in a UI requires thorough testing. Other insight such as how to access the graph with multi-threaded techniques requires understanding the "how" and "What" a class uses.
The Scene-Graph is contained by the Stage and is comprised of any subclass of node. Some nodes such as Panes may have children. A child is still a node. Children are contained in a structure which may contain other nodes that may also have children. Thus the graph is much like a multi-dimensional array or non-binary tree. It's also important to understand that: The Scene-Graph is a Non-Directional Graph meaning that a child can access its parent; a child can have only one parent; but can have an unlimited number of children. The getParent() method provides access to a nodes parent.
Image of scene-graph
Note that essentially the graph structure is a multi-dimensional array. Or in other words, an array that may contain either other arrays of items that inherit from Node, or Nodes such as ImageViews, Buttons, etc. Array like Nodes are Panes, Canvas's etc... which may contain other nodes.
This is important to understand when it comes to test automation & reliably assuring that a UI is displaying what it should show.
A good book to get started with JavaFX is "Learn JavaFX 8" by Kishori Sharan. https://www.amazon.com/Learn-JavaFX-Building-Experience-Interfaces/dp/148421143X/ref=asc_df_148421143X/?tag=bingshoppinga-20&linkCode=df0&hvadid={creative}&hvpos={adposition}&hvnetw=o&hvrand={random}&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl={devicemodel}&hvlocint=&hvlocphy=&hvtargid=pla-4584413736126928&psc=1
I have a JTree that stores "ShipmentItem"s and the .toString() on them shows the quantity, then the name of the ShipmentItem. At some point I change the quantity of multiple items at once but the toString() doesn't refresh until I've actually clicked on that particular tree node. I don't want to have to extend JTree to use 'Property Fired' I just want to be able to refresh it so that it shows the update.
I tried jtree.setModel(tree.getModel()) this didn't seem to work at all.
When you change something to your TreeModel (which you do by adjusting the ShipmentItem objects) you must make sure your TreeModel fires the correct event. This will cause the JTree to repaint the correct part. If you for example started from the DefaultTreeModel, your extension should call nodeChanged when the object of the node has changed.
Note: you do not have to adjust the toString method for correct rendering. The concept you are looking for is a TreeCellRenderer (check the Swing tutorial for more information)
I am trying to make simple Setting GUI in Java (IDE Eclipse).
On the left is JTree (7 nodes), on the right is layeredPane with 7 panels (JPanel). I want to browse panels by simple clicking on nodes in JTree.
But how to do it? Especially i do not know how to link node with this appropriate Panel. I do not know how to tag it, or to assign it as an object to the node.
P.S
1. I do not know, if there is more efficient way to do it.
2. I am new in Java, but not in programming. In Delphi there is no problem for me...
Thanx a lot
Each TreeNode has index which you can use to link to your panel.
If you use MutableTreeNode (default implementation is DefaultMutableTreeNode) you can assign custom user object to each node - see JavaDoc for MutableTreeNode and DefaultMutableTreeNode.
I have a JTree which I give objects that implement the TreeNode interface, and a custom TreeModel to display them (not using DefaultMutableTreeNode). I would like to change the text colour of some nodes. I can't find anything in the docs, except javax.swing.tree.DefaultTreeCellRenderer.setTextNonSelectionColor(Color newColor), but it will change everything indiscriminately, and I only need it for some nodes (specifically, broken links, i.e. nodes whose corresponding files can't be found on the disk, should be greyed out, the rest should be default). Can it be done, and how?
You are close to your answer. What you need to do is Sub Class the DefaultTreeCellRenderer and override a few of the DefaultTreeCellRenderer's methods. Then make sure you tell the tree to use your custom cell renderer.
What you will need to do is have some state variables that indicate whether or not a link is broken, and set the color of the node based on that.
You might also look at org.netbeans.swing.outline, mentioned in this answer. Ordinary extensions of TableCellRenderer and the RenderDataProvider interface make it especially easy to customize the appearance of rows in the tree.