I have a problem when I try to resize a JLabel. In my application appears the next strucutre. Understand every list item like something inside the previous list item.
JFrame (Layout null, fixed size, not resizeable, used by different people).
JPanel (Layout null, with a size of all the window, the place were I put my work).
various JPanel with different Layouts (the areas of content inside the main panel, you can think about it like html divs...).
Inside one of this "divs" with Layout null there are extended Classes of JPanel with Flow Layout.
Inside every one of this extedend Classes are labels with preferredSizes.
The thing is that when after create all of this i call theFrame.setVisible(true); and all works propertly.
But in a moment of the flow of my application I have to change the size of one of the labels. Then, I simply call label.setPreferredSize(d) and the change doesn't change. The function works propertly if I call it before set visible the frame, but not after.
I have the feeling that the problem is that I don't use nothing like pack(), validate(), repaint(), etc. Because I don't know what it works. I try call repaint and validate to the jlabel, and repaint the main panel, but doesn't works.
I'm relative new with awt and swing, and this is for homework. Sorry for my bad use of English language, and thank you for your help.
After you change the size of your JLabel, call revalidate(). This will cause the JLabel to be resized without waiting for an event that triggers a re-layout (such as resizing the parent Frame, etc...).
JLabel lbl_test;
lbl_test.setPreferredSize(new Dimension(100, 100) );
lbl_test.revalidate();
One other thing to keep in mind, as I'm not certain which class you're having problems with. Null layouts (absolute positioning) mixed with layout managers are going to cause some strange things to happen.
Related
I would hide a JButton in a JApplet. I'm using setVisible() method but I've a problem: it works but my GUI is shifted because of the absence of the component. Is there a way to hide a component and make its space occupied???
I know that is possible in Android, but in Java?
ps. To insert component in my JPanel I'm using GridBagLayout!
There are several ways to achieve this in general.
Most proper way is to layout other components in a way that they remain correctly attached at their current positions.
Since for complex layouts the proper way can be hard to get and especially hard to change afterwards, you can apply some layout 'hacks'. For example, instead of adding the button to the panel directly, you could add the button to a separate panel of its own (let's name it buttonPanel), and then add that panel together with the button to the panel containing the other components. That way when you remove the button, buttonPanel will stay to fill the gap.
However, depending on the way how you specified constraints, buttonPanel may shrink when you remove the button. To prevent this, just before removing the button, take the buttonPanel's width and set it as its minimum/preferred width; most LayoutManagers will respect this property.
Of course, you can always resort to hardcoding dimensions to avoid dynamic size calculations, but keep in mind issues with L&F and i18n.
Try using the setOpaque() method. Just do button.setOpaque(false); and that should do the trick. Does that work?
I want to add at runtime a JLabel under the purple pane which contains already some components, say under the progress bar:
Here is the structure of the elements:
And this is my code which is issued when an event occurs (it's getting there i checked with debug) :
jPanel1.add(new JLabel("Stack Overflow"));
jPanel1.revalidate();
jPanel3.revalidate();
I'm not seeing any changes whatsoever and have no clue where to go from here. When i put a
textarea in the purple pane and then call it's setText() method at the same place i try to add the JLabel component it works.
You need to learn more about layouts and how they work. I strongly suggest you read the entire layout manager tutorial, since understanding layouts are the solution here, and just using BorderLayout isn't the way to solve it. You'll likely want to nest layouts, perhaps using BorderLayout for the overall GUI, and having a central JPanel use BoxLayout to allow you to stack components on top of each other inside of it. Then perhaps add this JPanel to the main JPanel that uses BorderLayout in the BorderLayout.CENTER position.
Just a hunch, but maybe you need to call repaint() in addition to revalidate()
Java Swing revalidate() vs repaint()
I have a JFrame.
I also have a Box class which extends Component.
This box class has a paint method which makes a filled rectangle.
When I add multiple of these Box components to my JFrame, only the most recently added one is displayed when I call repaint on the JFrame.
I took a look at the layout managers, but I am not sure that's what I want. All I want is to be able to make an animation of whole bunch of rectangles wherever I want on the screen.
(I also tried creating a panel, adding the panel to the JFrame, and then adding all the Box components to the panel. This did not work either).
Thanks in advance!
You have 2 choices.
You can change the layout of your frame:
JFrame frame;
frame.setLayout(new FlowLayout());
Now, if you add more than one box, it will show up on the frame.
The other option is to do what you said you tried. (Adding a panel to the frame)
JPanel pane = new JPanel();
frame.add(pane);
(add the boxes to 'pane')
Also, you should be careful with the sizing of your Box. You will probably want a call to setPreferredSize() somewhere in the creation of the Box. This will tell Java what size to make the box when it is added to the layout.
You should also take a look at the Java Layout Manager Tutorials. There is lots of great info there.
And, one more thing. The reason only one box at a time was being displayed on the frame was because JFrame's layout manager is BorderLayout. And, when you call add on a component that has a BorderLayout, the component is automatically added to the center of the component. Subsequent calls to add will overwrite the center component, leaving only one component in the middle.
You do need to check out other layout managers. JFrame by default uses BorderLayout and without specifying the "place" a component is added, they get added to CENTER. Depending on what you want your UI to look like depends on the layout manager to use. I would suggest maybe using Netbeans GUI builder.
EDIT: Missed the part about what you want to add but the concept is still the same, if you just add these components to the default layout manager, they will get overwritten. Sounds like you may need to do your painting inside of just one of your Box components or create a JPanel and set the layout to null but then you would have to place them explicitly. Really depends on what you want to do with it exactly.
Do your layout on paper first, then read up on Swing layout managers.
Be aware that some Swing components only allow one component to be added to them. I've run across this when using Tabbed panes. Each tab can only accept one control (JPane?) so you have to create a separate panel with a layout to arrange the related controls and then as a unit add the pane to the tab. There are similar arrangements in the Swing library.
You could set the frame layout to null and then use setBounds() to position your boxes exactly where you want.
Thank you for all your answers.
Since I am using my own custom class, Box, I have the ability of setting the position of my the rectangle through the paint method.
I realized my Box class was extending the wrong thing. It should have been extending javax.swing.Jcomponent.
If I now use a panel with an OverlayLayout, add my components to that panel, they all show up properly.
I am trying to figure out why my JComponent refreshes when I manually drag my window, but it doesn't refresh when I call repaint or revalidate. The data is ready to be displayed, but it just won't show until I manually resize. Can anybody give some suggestions about what I can do or does this sound like it isn't a Swing problem since I tried repaint and revalidate?
One weird things I've noticed is that if I have this code:
sp.setSize(sp.getSize().width, sp.getSize().height+1);
sp.setSize(sp.getSize().width, sp.getSize().height-1);
If the first line is used, then the JComponent will refresh itself. If I use none or both of these lines it will not, which seems bizarre to me.
I am basically just putting a JPanel in a JInternalFrame in a JDesktopPane. There are two main functions for what I am trying to do. One adds the new JPanel and the other tries to refresh it so the new data will show:
public void addNewSP()
{
sp = new JInternalFrame("SP");
sp.setClosable(true);
sp.setLocation(700, 400); //this should be changed to something based on screen size
sp.setResizable(true);
sp.add(popUp);
this.parentContainer.add(sp, JLayeredPane.DRAG_LAYER);
sp.pack();
sp.show();
sp.setSize(500, 500);
sp.setPreferredSize(new Dimension(500, 500));
}
public void refreshSP()
{
sp.repaint();
sp.validate();
sp.repaint();
sp.validate();
parentContainer.validate();
parentContainer.repaint();
sp.setSize(sp.getSize().width, sp.getSize().height+1);
sp.setSize(sp.getSize().width, sp.getSize().height-1);
}
}
BTW parentContainer is the JDesktopPane
When changing the container's content, you have to call both:
revalidate() to make it recompute the layout for its content
repaint() to request a repaint for this container
but it just won't show until I manually resize.
We don't know the context of your question, which is why a SSCCE should always be posted as suggested earlier.
In general a JComponent, does not have a preferred size, so I'm guessing Swing doesn't think it needs to paint the component. When you resize the frame, chances are the component was added to the center of a BorderLayout so it automatically gets sized to fill the entire space of the frame.
The solution is to give your component a "preferred size" so that any layout manager can use this information to display the component properly.
if your are modifying container's subcomponents you should call jcomponent.validate();
I assume parentContainer is the JDesktopPane?
What kind of changes are you making to sp that are not showing up?
Changing the size of sp will cause Swing to repaint from scratch. That's why the setSize() is fixing the display.
Most likely, the changes you are making are either not happening on the EDT, or are not invalidating the right container. For example, if you change the visibility of a component in sp, you'll need to call sp.invalidate() to rerun the layout manager.
Have you checked that you're only changing components (or their models) on the EDT?
A quick test for that is to run with the Substance LAF as it will complain if you change things on another thread.
I'm using Netbean's form creator and I'm trying out some things. I'm not sure if it's the layout manager, but when I create my own JPanel and add it to the main content pane of the my window, the size of the panel always maximizes inside the FrameView no matter what re-dimensioning methodology I use such as setSize or setPreferred size. I'm very new to AWT and Swing.
With NetBeans WYSIWYG designer it's a peace of cake - just be sure to use Free Form Design and use mouse for resizing. Maybe the panel is itself larger than FrameView, so double click on it (you are editing it exclusively) and make it smaller. Than double click to get back to parent component and you should be fine.
Or maybe check some tutorials at NetBeans site.
You're not supposed to set sizes manually. Leave that to the layout managers, and your GUI will not break when the window size or the font or even just a button label changes.
The trick with layout managers is that you can use not just one but several, in nested JPanels. That way, nearly any layout is possible.
This happens because the layout manager of JPanel's container (perhaps it is either JFrame or another JPanel) instructs the JPanel to maximize.
Do the following:
Find out, who is the parent of this JPanel (take a look at NetBeans's containment object tree)
Check, what layout is defined for the container
Read the documentation about LayoutManager's (they're in java.awt package)
???
PROFIT!
In my experience, Swing is a very picky thing. I'd try setMaximumSize and setPreferedSize. As a side note though: when ever I used GridLayout, it always stretches whatever is in each of the cells (to make it symmetrical I guess). Flow, Box, Border, and I think GridBag don't have that problem though.
-Brett