Develop Reference

Select from a UI list and perform an action

we're building a small chat app for an assignement in our university. I have a question regarding how I can implement something.
This is our ui. The big white part is a jTabbedPane where conversations the user is participating in will appear. The two small ones are where active groups and active users will appear.
I found out that I can populate a jcombobox from a linkedlist using .toArray. I don't know what ui element to use, in order to display the list elements one under the other, and being "selectable" (only one at a time). The concept is that the user will select a group and press "Join", to, well, join.
This is what I have in my as to how it will look in the end.
Any pointers and advice in general would be greatly appreciated.

It looks like you're wanting to use either a JTable or a JList -- one with a custom renderer, a renderer that displays both the group name and its "status"(?).
If a JTable, then your key job is to create a TableModel that will accept your data well, either by using the DefaultTableModel (the easiest way to do this), or by creating your own model derived from the AbstractTableModel (a little more difficult, but more flexible).
For a more detailed answer, consider providing pertinent code, preferably as a minimal example program or MCVE.

What is a good practice to handle a lot of checkboxes in JavaFX

I need to build a View which has a 4 layer nested Multi-Accordion with a lot of checkboxes inside them. All together there might be around 30-40 Checkboxes all through the Accordions.
The next step will be, that i have some sort of logic behind all this. Depending on the selection combination of the checkboxes I will change a text label accordingly.
My thought process was: I put up all these checkboxes and give them a numeric fx:id representing there position in the nested accordion graph. Something like "1_1" or "2_4_1".
After that, I build one ChangeListener calling a Method on Selection of a Checkbox. I can look up the Id of the checked box, look it up in my data (to see which Text belongs to it and if any rules interfer with other boxes) and handle the logic accordingly while putting the id and its text in a Map or List to keep it for later and to keep track of the checked boxes.
Now I came to know, that getting the fx:id isnt something JavaFX wants me to do. I cant deliver a custom id in custom property inside the FXML either (couldnt find anything regarding this).
I am now pretty much at the end of my knowledge (I did just start with JavaFX and have some basic Java knowledge) and it seems to me, that I tackle this topic from the wrong side.
My question is now: What would be a best practice to handle dozens of checkboxes and trigger logic in the code according to the box that was checked without writing a ChangeListener for every single Check Box leaving me with some (imo) ugly code all the way.
EDIT: I forgot to mention: I did achieve some sort of functional solution by writing a custom CheckboxChangeListener with a reference to the Element the addListener method was called on and using "getId()" on this reference. I came to know though, that this method references the css:id of the fxml element and not its fx:id and I am not quite sure if this is a proper way to go

You should look into databinding with javafx. For example:
CheckBox cb1 = new CheckBox("1");
CheckBox cb2 = new CheckBox("2");
BooleanProperty isCb1Selected = cb1.selectedProperty();
BooleanProperty isCb2Selected = cb2.selectedProperty();
Textfield foo = new TextField().visibleProperty().bind(isCb1Selected.and(isCb2Selected));
This would hide the textfield foo if atleast one of the checkboxes isn't selected.
You can find other examples here and here an oracle tutorial

Java GUI architecture for larger project

I want to make an app, which will work as interface to several servers.
Why: In web iface provided by default (and we cannot change it) are few things we miss, few could be done better and for sure automation of some stuff would make the job easier.
What do I have: almost finished classes for communication with web interface of a server app.
GUI description:
For some kind of version 0.1: text field for username, radio button to select server and one "go" button. Then several (4-12) action buttons to operate on data, 2x text area with results, one label with some text data - I can manage this.
Then I need to view the data - grid MxN which will load the data, expected size: 7-15 columns, usually 10 rows or less, but rarely it can go over 1k (or even more, but I don't need all to be visible to the user in that case).
What I need: simply an advice.
I wish to start with a simple version (and I'm working on that already, but I'm stuck on too many things - 95% cos and absolutely new to GUI and 5% cos I'm new to java).
I've checked many tutorials, but they're all simple.
Real questions:
1) Verify. In MVC controller should handle all user actions - is it done by view's method which is something like button.addActionListener(param); anotherButton.addActionListener(paramp; ...?
1b) I've seen all implemented via one (nested) class, which was then checking source or smth - is that ok? There will be a lots of buttons etc.
2) How to implement the data grid, when I need to take actions on click / dbl click?
4) First row is header, the rest should be scroll able - should it be in the grid or outside (its own grid):
4a) How to make sure header's size (width) will be the same as in data (I don't want to set up straight size)
4b) I failed to create anything scrollable so far, but thats my bad I guess. How to ensure header will hold on a place and the rest can be scrolled?
5) How should be "data update" implemented? I've got JPanel from which I remove grid component and then I make new one and add data into it (simple, but perhapss there is another way). One of first enhancements will be sorting - use the same way I used for new content?
Thanks a lot for any answer, I know this is not very specific, but example I've found are too simple.
I plan a lots of enhancements, but thats in the future and I don't mind to rework GUI/Controller several times, at least, I'll practise, but I don't want to finish one part of the code and realise I've got to rewrite half of a controller and 1/4 of a view to make it possible.
Note: I plan to use this at work as my tool (if things go right, I could make 25-50% of my work by few clicks :-)
So I really mean this).
Note#2: I'm not new to programing, but I've never created GUI (which is why I've got GUI with menu bar with 2 items and 3 components and almost done web-iface connections).
Note#:3 dragable data header, tabbed data view - thats the plan for the future :-)

MVC in Swing is examined here; use nested classes for ease in prototyping and creating an mcve for future questions; as the need arises, nested classes can be promoted to separate classes having package-private access.
Use JTable; its flyweight implementation of renderers is good for organizing data by row and column.
Item three does not exist, but "always remember to translate cell coordinates" if you plan to drag columns or sort rows.
Use a JScrollPane to keep the table header stationary.
Update the TableModel, and the listening view will update itself in response.

If you are interested not only from the event/messaging architecture, but also on handling mouse/keyboard input, hovering detection, widgets, temporary menus, form re-sizing with widget alignment, dragging and dropping etc. I can advice you to look at this question and my answer with helpful resources.

How to make an expandable list with Java Swing

I need to make an expandable list using java swing. I will attempt to demonstrate:
Unexpanded:
>[Expand me!]
>[And me!]
Expanded:
|[Expand me!]
>[Expand us too!]
>[Expand us too!]
>[Expand us too!]
>[And me!]
So, when you click on the "Expand me" portion of the list, another lists will drop down, possibly containing more expandable lists. If you were to click on it again, it's "sub-lists" would then retract. Pretty basic. And, as you can see, I am not looking for JComboBox, and I do not think JList can do this. If someone were to point me in the right direction, or give some programming examples, I would be grateful.
Thanks,
MirroredFate

How about using a JTree.
A control that displays a set of hierarchical data as an outline.

You can try using a JTable and put a button in the first column. When the button is clicked you add more data in the rows in between.
update
Something like this:
Or this
I think the first uses a JTree but that the idea.
BTW these two belong to JIDE Soft, check if it is feasible for you to buy a license:
http://www.jidesoft.com/products/grids.htm
Is not trivial to roll you own but is not impossible either.

check for TreeTable or one example or Outline, but with notice, that on official Java (SnOracle) pages any progress died ...,

How to globally modify/access widget in GWT?

I just started yesterday using GWT, so maybe I'm not using the proper mechanism to solve that problem. So, I will try to explain exactly what I'm trying to do (with a simple problem) and 2 solutions I came up with to address that problem.
Problem:
Remember an index that can be updated via other widgets. Let's use focus to represent it.
[button 1]
[button 2] [button A]
[button 3]
The buttons [1..3] and [A] are not in the same class and need to find the element using the id using the DOM. The reason is that those 2 views needs to be orthogonal.
We can use up/down key to move the focus from button 1 to 3.
If we are on the buttons [1..3] and press right, we go to button A.
If we are on the button A and press left, we go to button previously focused.
What we want to do is save or set the focus index when pressing right.
Solution 1: Global variables
I'm not usually fond of global variables, but in some case it's handy. By using, for instance, a dictionary (Dictionary.getDictionary) defined globally in the javascript, I could save the current index in it using the "Focus Event" in that case.
So, in the key press event, when left would be fired, I would just read the value in the dictionary.
I haven't tested yet, but I think it should work.
Solution 2: Set the value with the Element
Element element = DOM.getElementById("button id A");
element.<setFocusLeftKey>("button id [1..3]");
Here what I would like to achieve is just in the "onFocus" Event, I would simply set the value of that button.
So is it possible to cast/find the object with the Element? I think that if there is no easy way, it's probably because it's not recommended.
Is there a simpler way/other method to achieve that?
So, any thought or solutions?
Thanks in advance.
P.S. I haven't found a better title for that, so if any suggestion, just put it in the comments and I'll update it.

Using ID is definitely not the suggested way to do this in GWT. You say you need this mechanism to keep your views orthogonal to one another. This is noble, but in GWT you would achieve by using another resource (an EventBus, implemented in SimpleEventBus) that hides the different components from one another. In fact, I would argue that looking up the element by ID strongly couples the two views and is smelly.
Armed your EventBus you simply create and fire custom events that let the views (or, better, their presenters) communcate with one another. For example here you could have: NavigateRightFromButtonsEvent and NavigagteLeftFromButtonA event.
However, depending on the size of your app (or as a first experiment) you could decide to couple your two views. In this case simply pass the view for the button list into the one for button A and vice-versa. This is not really worse than relying on a global ID.
No matter which mechanism you choose (event bus or wiring the views together), you should now have access directly to the instance of the widget you want to highlight. To focus, just call setFocus(true) on it.