I've been looking all over for some mention of this, but I cannot find any substantial information on it. Is there a way to change the z-order of Swing components, or at least change the draw order so that they appear to be above others?
You are looking for setComponentZOrder
Here's an example.
If you want to overlay components over other components, you should use JLayeredPane, which will let you add components to specific layers. This is precisely what's used for things like tooltips and drag-and-drop operations.
Here's a tutorial for it as well.
Look at the setComponentZOrder(...) method of the Container class.
You can also check out the Overlap Layout which has a brief description on how ZOrder works.
Related
I am a self-taught java developer and I use IntelliJ IDEA for Java. Recently I saw a video on youtube in which the guy was using NetBeans and in his JFrame form, he was able to freely place his objects like JButton, JTextFeild, JLabel, etc. I am not able to figure out how to do that. In IntelliJ IDEA I found several layout managers such as Border, Card, Grid, Bag, etc. but none of them gave the desired result. can somebody please tell me how can I get a layout manager in which I can freely place all my objects and also freely resize them without any restrictions? Thank you in advance for any help.
In swing every component extends Container. That means that every component can have nested components (they all have add(Component) method). However, not all of them support the layout-ing of nested components.
What I want to say is, that you can add a component to a JButton, but a JButton is not capable of showing its nested components.
So, in order to have nesting, we use the components - containers that support the orientation of their nested components.
These components are all windows (JFrame, JDialog, etc...) and JPanels. There some others that support layout-ing a specific type of nested components. For example a JMenu is capable of showing JMenuItems properly.
Now, these "top-level"/empty containers are using Layout Managers in order to align-show their nested components. Based on the container's layout manager, the components are shown.
This is why you can't "freely" place the components into a JFrame. Because its Layout Manager is taking care of the components will be placed. So, what you are looking for, is to change its LayoutManager (use setLayout method) to one that allows you to freely place the components.
Guess what? There is no such layout manager. Simply because, it would have nothing to do/calculate since you are taking care the layout of the components. So, in order to achieve the "free" component layout, you must use jframe.setLayout(null);. In order to layout the components after it, you will have to use componentInsideJFrame.setBounds(...) and give it constant coordinates /dimension.
This is bad practice. A very bad one when it comes to UI. Giving a component static coordinates and dimension is bad. There are some questions you have to ask yourself.
What if user resizes the window? If the window is 301x301, the center of it, is at (150,150). So you place a component at (150,150). Ok it works. Now user resizes the window and makes it 501x501. The center is now standing at (250,250). But the component is staying at (150,150). There is the solution of setResizable(false), to this kind of problems, but how often have you used "uncapable of resizing" applications? What if user wants to resize it?
I hope you get it and understood what I am trying to say.
By using layout managers, you are solving this kind of problems easily, since the layout manager will take care of the resize and calculate the new center.
Yes. I know it feels weird, but all these youtube tutorials are not teaching you the correct way to make Swing GUIs. (This is a conversation for another day, I guess)
I truly suggest you read the tutorials of Swing documentation in order to get some ideas of how layout managers work. You will really benefit from those.
Finally, I suggest you to leave outside the whole "gui-builder-tool" thing. They seem to help you building your GUI, but they are adding so much additional/useless code and most of the times they are "bad UI creation" prone. Try to code the GUI by yourself.
At first, this sounds a bit harsh, but you can always run your application and see the result of the GUI. After some mistakes, you will finally be able to imagine the GUI result by only seeing the container.setLayout(..) and container.add(...) lines.
When creating Swing GUI's, how can I best choose the horizontal and vertical gaps to be used to separate components? Something like asked here Windows Layout Look and Feel, but platform independent.
Generally I simply used 5 pixels for everything, that looked reasonable with the Windows Classic theme, but looks somewhat odd when running under Windows 8, especially when there are multiple nested container components (e.g. Dialog -> TabbedPane -> ScrollPane).
I have looked at UIDefaults, but there doesn't really seems to be any hints about component spacing there (I was hoping to find at least a few values that could be used as hints, but LayoutManagers seem to generally use hardcoded deafults, e.g. FlowLayout uses a hardcoded 5 pixel spacing).
What approaches can I take to make my layouts more look and feel aware (I am generally using the System Look and Feel) ?
If you want a layout of components that change a bit to fit your user's platform, then perhaps just use the user's system look and feel with:
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
Edit to provide solution for specifying more specific gaps.
To specify margin and padding between components you can try using a box layout. You might not need to use a box layout throughout the entire Swing code you have either, perhaps have a utility function you use right before you add a component that accepts a Swing component, and a left right top and bottom margin/padding. This function would then return you a JPanel with a box layout with the margin/padding passed, along with containing one component, the one you passed in.
I'm programming this level creator for a game me and a few of my friends are doing but as of right now the GUI is using a null layout, which I don't want to. It works fine for now, but I'm still against it and I know everyone else also encourages you to ALWAYS use a LayoutManager. I'm not really willing to compromise the design as it is right now, so I pretty much want to know if there's a LayoutManager that allows me to create a GUI that looks like this:
IT HAS TO BE IN THE STANDARD JAVA API! :)
This looks like a good job for a BorderLayout. Put the buttons inside a nested container as the NORTH element. Add the JScrollPane as the CENTER component. The grid itself looks like it is a good candidate for a GridBagLayout or perhaps a GridLayout.
Short answer, yes: GridBagLayout. But that'll be a pain to work out and debug.
Long answer: It looks to me like you could do this best with a BorderLayout, a JPanel for the JButtons, and a JTable with custom TableCellRenderers and TableCellEditors.
Check the excellent documentation available for Java by Sun itself:
http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
Can you spot the GridLayout and GridBagLayout? If you put it into a scrollable container, that should do the trick.
Use GroupLayout for the overall panel and a custom paint method for the map.
I don't think many people here would recommend GroupLayout because it's more complicated than the other layout managers. I like it because it produces great scalable results, so I invested the time in understanding it. Now, I hardly use anything else - especially for user interaction panels with buttons and text fields.
For the map, though, I would create a custom MapPanel and overwrite paintComponent(). Sure you have to write your own custom scrolling algorithm, but I think that's a small benefit for not having to deal with scroll bars. You could make it so someone could just drag the mouse around and move the map. Use the mouse wheel to zoom, and make the interface very intuituve. If you want to paint scrollbars, you can do that too.
I've built several interfaces using models like this. I've built several maps for games using this model, as well as a financial market charting package. It makes it very easy to add custom functionality to do some great things that would be a nightmare to try to do in a JTable.
I'm new to layout managers like Flow, borders, ...
I mostly use setBounds() to set the position of my components.
I read on an article that using setBounds is not an good practice and it's better to use some layout.
Which are the best and most used layouts?
How to position a button using layout managers; instead of doing setbounds(10,10,100,30)?
look here: http://download.oracle.com/javase/tutorial/uiswing/layout/using.html
Basically you should forget about coordinates. Look at your dialogs at a higher level of design. Questions you should ask yourself.
1) Is there a "main" area with smaller surrounding areas in your design. If so use a BorderLayout.
2) Is there equal grid like areas in your design, If so use a GridLayout.
3) If you need a top-down, or left-right layout, consider a BoxLayout
4) If you want to show a complex form, probably use a FormLayout from jgoodies.
But you have to look at things from a high level. There may be subsections in any one top level section of your dialog. If that is the case, then you need to put a JPanel in that section, and then use a sub layout in that JPanel. Use the above questions over again for that panel.
Besides "standard" Swing layouts (part of the JDK), there are many third-party (mostly open source) LayoutManagers that often are much better than Swing ones.
For a comparison of many LayoutManagers on a real example (with code), check out this link, although a bit old, it still shows the various features and ease of use of predominant LayoutManagers nowadays.
In general, I would advise DesignGridLayout which, although quite powerful, is very easy to use (you don't need a GUI designer to use and it's easy to maintain layout code of existing panels); it just takes one hour to understand it.
Also, MigLayout is viewed as the most flexible one (might be useful if you need very complex layouts), but it takes more time to get used to it, and sometimes you have to use "tricks"to make it work as you want.
..which is the best and most used layout (?)
Nested layouts. Use whatever layout works best for different groups of GUI components, then put them in panels inside other panels (with other layouts). See this Nested Layout Example for a demo. of combining layouts.
As to which best individual layouts to use, do the tutorial linked by MBFG to get a feel for what each can achieve, their strengths & weaknesses.
I will commonly use nested combinations of BorderLayout, GridLayout & FlowLayout, with an occasional GridBagLayout.
I am creating an application which has a scrollable and scalable (zoomable) view. Inside this view I want to place other components (most of them customized JPanels and JInternalFrames).
Things such as fonts and borders, and sub-elements such as buttons don't need to be scalable. Only dimensions and position of container components should be.
What do you think, what is a good way to implement scalable components?
EDIT: I'm talking about resizing the entire layout including all
components. Please think of something such as a visual UML editor with zoom functionality.
My alternatives are:
Create a custom layout manager;
Create custom resizeable sub-components;
Create a custom container which would take care of resizing its sub-components;
Do something else?
Possible problems:
Boilerplate code;
Necessity to provide access to additional custom properties of components;
Not straightforward (inconsistent) representation of components in code.
Something else?
This is why layout managers exist: they tell contained components where and how large they should be.
Since you're talking about a UML editor, are you using contained Swing components to represent the various objects in the diagram (eg, a component for a class)? If yes, then you've got a lot of work ahead of you (although it's not necessarily a bad approach). I'd recommend creating a constraints object that identifies the object's location on a "unit space," then multiplying by the current size.
I've done that by creating a custom layout manager. Every component (or rather component class) on the frame has a marker whether or not it shall be resized when the container is resized (e.g. tables are resized, buttons are not). Those which are not resized are moved when the container is resized.
This is used to make resizeable forms without any manual setup, i.e. forms are defined by just specifying x/y/length/width for each component (no further alignment info).
If I look at this problem as visual UML editor then I had to think about single "canvas" component drawing each element as graphical object with base aspect ration and zooming in/out. I can't see reason for list of components aligned within parent container.
I started a similar solution that works fine without touching the original layout.
It's as easy as this:
// Install scalable layout and CTRL+/CTRL- keys for scaling operations
ScalableLayoutUtils.installScalableLayoutAndKeys(new DefaultScalableLayoutRegistry(), frame, 0.1);
It's still under work but It will be soon available as part of the next "utils4swing" version.