I am just catching up with some of the new features in J7 and am perplexed by the addition of these JLayers in Swing. Since they're so new I am having tremendous difficulty finding good literature on them and the best practices of using them.
Could anybody point me in the right direction or provide an example of what these components do and what purposes they (generally) serve?
Thanks for any input!
A JLayer can be used to dynamically enhance any of your existing components.
Say you have some custom button (say MyJButton) and you want to add a mouse over effect or maybe some shading. Traditionally you would create a new class that inherits from MyJButton that would implement your new features.
One problem with this is approach is that the new effects are only applicable to MyJButton (since your new class extends MyJButton). Another problem with this approach is that you can't change the enhancements / effects at run time, since inheritance relations are fixed at compile time.
Using a JLayer, you can put a LayerUI together with any existing Component (not just a JButton or MyJButton) in order to add your custom effects to a component. If you have a LayerUI that does shading, you can put it together with a JButton, JTextField, JPanel or any other component to perform that shading. You can also change the composition of LayerUIs and Components at run time.
The JLayer is just a special case of the decorator pattern.
http://www.intermediatejava.com/2011/06/jlayer-for-swing/
Related
I have a Swing custom control which serves an almost identical function to a JLabel. It's not accessible by default for people who use assistive technology, like a screen reader. I'm working on the Megamek GitHub Project, and trying to figure out how to associate the PMSimpleLabel class with other objects, as in the JLabel class's setLabelFor method.
The approach taken so far seems to be to more or less ape the JLabel's accessibility implementation. I'm not sure if this is the right way to go about it, there seem to be some elements in the latter I'm not understanding.
The problem turns out to be largely because of the custom components. The AccessibleJComponent class has a fallback mechanism to name controls which don't ohterwise have accessible names, but this is hard-coded to look for a JLabel and not a custom label class.
There are a few work-arounds for this, such as modifying the get/setAccessibleName methods, or switching to using the accessible description instead.
The solution in the long term is probably to use regular Swing components where possible
I've been tasked with making a GUI that essentially takes a bit of user input and does some folder/file manipulation on various drives accessible by the machine the program is being run on. While designing this GUI, I'm starting to realize that MVC will make my life much easier and anyone else who decides to modify code, but I can't really see how this can be done via NetBeans.
I've done a bit of reading up on this topic, and I can't really see any clear cut answers as to whether or not this can be done on NetBeans. Surely it can be done if I programmatically build the GUI, but that somewhat defeats the purpose of why I chose to use NetBeans.
Netbeans is fine to do this.
The key thing to realize is that while all of the basic Swing components are MVC, for the most part you don't interact with them that way. A simple text field has it internal model, but that model isn't your model, the text field is more a primitive.
Your model deals with higher level events (button actions and what not), rather than button presses and arrow moves and mouse clicks.
So, for high level MVC, the primary mechanism of communication is through PropertyChangeListeners. And the basic task of building your app up is wiring the PCLs of the assorted data elements along with their GUI components together.
For example, a simple case is you have a list of items. And that list is rendered on the screen via a JTable, and that table is on a JPanel.
Your list has it's own model, i.e. it's not simply a Java List. It's not a List because standard Java Lists don't support PCL notifications. But your Model would obviously wrap such a List.
Now, the next question is how do you wire up JTable to be associated with your List model.
One, you could subclass JTable and bind it to your Model. Or, more simply, you use the JTable as a primitive, and let the enclosing JPanel manage the interaction between your Model and the JTable.
That means having your JPanel implement PropertyChangeListener, and then, when wiring everything up, you do something like this:
ListModel myModel = new ListModel();
ListPanel myPanel = new ListPanel();
myModel.addPropertyChangeListener(myPanel);
Now, whenever your ListModel is changed, is will notify the ListPanel.
On your ListPanel you can having something like:
#Override
public void propertyChange(PropertyChangeEvent evt) {
if (evt.getPropertyName().equals(ListModel.CHANGED)) {
ListModel model = (ListModel) evt.getSource();
DefaultTableModel tm = (DefaultTableModel) listTable.getModel();
tm.setRowCount(0);
for (String s : model.getList()) {
tm.addRow(new Object[]{s});
}
}
}
Now, you can see this simply reloads the entire table model, but you can make your property changes as fine grained as you want. You can also see that if this was some other model (like a Person or something) you can populate individual text fields and whatnot on the panel.
This is a pretty simple GUI, but it shows the fundamentals of how this all wires together. I think a bit of this is lost in the Swing examples which are great for one panel screens but don't scale at all when you start adding other views.
Your JPanels basically become combined VC, as your GUI gains complexity you can factor those kinds of things out, but its works pretty well for reasonable amounts of screens and such.
There are two ways in which Netbeans can help you leverage its codebase: GUI Builder (1) and NB Platform (2).
(1) Netbeans had for a while one of the better drag-n-drop GUI builders in the Java world, codenamed Matisse.
That said, it's been a long time since I worked with it - and I never really liked the generated code, it wasn't very comprehensible (which of course is not the purpose of auto-generated code). For more complex UIs we hand-wrote the layout and the work was bearable, even if not the most pleasant. For simple UIs, I'd try GUI Builder again, for complex UIs with a lot of wired logic, I'd probably still would write it by hand.
To see how the GUI Builder works, take a look at one of the many tutorial videos, e.g. this one:
NetBeans GUI Builder: Adding Components
(2) Netbeans Platform is to Netbeans, what RCP is to Eclipse. A rich set of components developed for an IDE, that can be reused. I briefly looked into NB Platform and we would have used it, if the project didn't change course. Maybe this SO question can shed more light on this aspect: Which Rich Client Platform to use?.
Concerning MVC. There was JSR 296, a generic Swing Application Framework, that looked somewhat promising, but was withdrawn in 2011. That did not stop people to fork it and work on it, as this project shows: Better Swing Application Framework, with a release in mid 2012. Even if you do not use such a framework, please do not put all code in one class (as you mention in you comment), but create a simple model/controller and keep the UI components separate. It does not need to be fancy for a simple app, a minimal MVC-ish separation of concerns might suffice.
I also hit this problem and i found a link which gives a good example how to seperate the controller from the view using the NetBeans GUI builder.
Here is the link.
I have tons of jbuttons, jtextfields, jlabels, jmenus, gui items and it is extremely time consuming to set the background color and foreground color one at a time.
I want to be able to color the fonts(foreground) and backgrounds all the jmenus, jmenuitems,jtextfields,jbuttons, etc quickly/concisely in my project instead of having to set them one at a time.
Is there any technique to do this more concisely instead of doing it one at a time?
1) most eficient way would be to use Custom Look and Feel, part of them have got a nice Themes
2) set value to the UIDefault, Listing UIDefault Properties
EDIT:
best of all UIManager Defaults by #camickr
You can combine Swing with CSS or use a Swing Look & Feel in order to create a standard look for your components. The Java site says:
Before we get into a CSS implementation, let's consider the alternative: a custom look and feel. Swing Look and Feels (L&Fs) are sets of classes that implement the actual drawing of components at a very low level (think lines and bitmaps). They can be swapped out for new ones at runtime, often to implement the look of a native platform; i.e., the JDK for OSX has a set of classes that make Swing apps look like native Aqua apps, with candy buttons and blue tint. Custom L&Fs are powerful, but not trivial or quick to build. You will usually have to touch 20 or so classes and implement a whole bunch of special drawing code.
So CSS is easier to use. The same article goes on to give a tutorial about how to implement the CSS with Swing. They provide a nice walkthrough of creating the right rules and then going on to implement them in CSS. However, this is not simply "copy and paste" code.
If you'd just like to use a package (without having to code it yourself) the answers to the question Can I use CSS for Java Swing? suggest Flying Saucer and Jaxx.
They're all JComponents so you can make an ArrayList of everything:
//Adding everything to the ArrayList
ArrayList<JComponent> myComponents = new ArrayList<JComponents>();
JButton b1 = new JButton("Button 1");
myComponents.add(b1);
JMenuItem item = new JMenuItem("Menu Item 1");
myComponents.add(item);
//Coloring the foreground/background
for(JComponent j : myComponents) {
j.setForeground(new Color("BLUE"));
j.setBackground(new Color("RED"));
}
If you use a Look and Feel that honors the UI constants in javax.swing.UIManager then you can just set them. There are values for e.g. panel background. If not or if you can't control the look enough by this you can write you own UI delegate that draws a specific component (e.g. javax.swing.plaf.ButtonUI for JButtons). If even this is not enough you can write your own Look And Feel. If you just extend the Metal LnF it is not that hard, you would write own UI delegates and set properties, like above, but centralized.
I have a fairly complicated JTable subclass (WidgetTable and its WidgetTableModel) that works fine when I add it to a dummy JPanel for testing purposes.
Since I am absolutely horrid at working with LayoutManagers, I like to use the NetBeans built-in GUI Builder for all my layout work. Then I usually just code-around the autogenerated (GUI builder) code and that has always worked for me. It is the best of both worlds: I get my presentation looking exactly the way I want it, and I also get fine-grained control over the componentry.
However, I have never used the GUI Builder tool to make tables. After tinkering around with it for a while last night, it looks as though it is only good for making pretty basic (fixed # of rows, fixed # of columns, etc.) JTables.
My WidgetTable actually has a dynamic number of both rows and columns, special editors/renderers and many other bells and whistles.
My problem:
I have two conflicting constraints: (1) I need to use the GUI builder to position and size the table exactly where I want it in the container, but, (2) The table component available through the GUI builder is too basic to handle my WidgetTable.
I need a way to design a "table placeholder" into my container with the GUI builder, such that, once NetBeans autogenerates that placeholder code, I tweak the code and instruct it to dynamically instantiate one of my WidgetTables instead, consuming the location and size that I defined the placeholder component to take up.
This way I can have my cake, and eat it too. The only problem is, I don't think the GUI builder supports this ability to drag-n-drop abstract JComponents, position and size them, and then plug subclasses into them elsewhere in the codebase.
Anybody ever have this problem before or have any interesting recommendations? I imagine the best thing to do would be for me to just roll up my sleeves and learn LayoutManagers, but I'm mostly a server-side developer and only come over to the client-side every once in a blue moon; and honestly, don't have the energy to learn the intricacies and nastiness of GroupLayout and its sinister cousins.
Thanks for any help!
Insert a JTable using the GUI builder, reset its model property to the default value, and tweak the construction code so that it looks like
jTable1 = new WidgetTable(this.widgetTableModel);
You may tweak the creation code by right-clicking on the JTable, selecting "Customize code", choosing "custom creation" instead of "default code" in the first combo box, and typing the code for the constructor call.
If you need your jTable1 variable to be of type WidgetTable rather than JTable, edit the "Variable declaration code" in the same dialog box.
NetBeans also allows you to create custom components for building UIs. This may be more work than you want to put into your WidgetTable, but if you think you're going to have to build more UIs with custom components, it could be worth learning.
I do this all the time. I have an subclassed JTable that I use with the GUI editor and it is Dynamic.
Add a JTable to your project using the GUI editor and the layout of your choice.
Once the table is added, right click on it and click on custom code.
In the constructor of the JTable, change it to say new WidgetTable(new WidgetModel()) instead of new JTable(new DefaultTableModel()).
Create a global variable for you WidgetTable. Something like private WidgetTable widgetTable;
In you constructor, after the call to initComponents(), cast your JTable to a Widget table and use that from now on.
`widgetTable = (WidgetTable)jTable1;
I need a multi-value JSlider (or a similar component) for an analysis application. The two features missing from the regular JSlider are the ability to have more than one knob and also the ability to add or remove knobs on the fly. The reason for this is that they will be used to partition the 0..100% range for a particular factor into two or more subranges which are fed into a binning algorithm.
After some unsuccessful googling, it seems I'll have to develop a custom component (which I'm not very good at, I've been coding in Java for 10 years, but have zero experience in Swing). Is it possible to extend (easily :-) the JSlider component? Or are there better alternatives, perhaps not Swing-based but web-based? I have some flexibility in selecting the GUI approach for this. The current analysis application is command-line so a Swing GUI would be most straighforward, but nothing really prevents me for turning it into a web app if need be.
Thank you!
Take a look at JXMultiThumbSlider in SwingX.