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Java Swing JPanel scrollpane not working? [duplicate]

Before I start, I'm aware that its a bad idea to not use a Layout Manager and usually I do use one, however, I also have all my components automatically re-size and relocate based on the size of the window. In addition the program I'm working on is only intended to run on 1 machine throughout its entire lifetime. Please don't downvote me just because of lack of layout manager, I found it to be what I need for this particular program.
To my issue, I found a similar post on stackoverflow but a solution was never achieved.
I'm adding a dynamic amount of JLabels to my JPanel, I've noticed that when not using a layout manager, the scroller doesn't work.
This is a simplified version of my initialization code.
JPanel mypanel = new JPanel();
mypanel.setLayout(null);
mypanel.setSize(800,450);
mypanel.setForeground(Color.WHITE);
mypanel.setBackground(Color.BLACK);
scrollablePanel = new JScrollPane(mypanel);
scrollablePanel.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
scrollablePanel.setPreferredSize(new Dimension(800,300));
scrollablePanel.setSize(800,300);
scrollablePanel.setLocation(250,156);
myContainer.add(scrollablePanel);
where myContainer would be the container (also without a layout manager). The JLabels are added later on to the JPanel with:
enter code heremypanel.add(label1);
after some basic settings are set for the labels such as setForeground and setBackground.
Unfortunately when run, the scrollbar appears as if its not required (see image)
http://i.imgur.com/zp0QKGG.png
The table text seen in the image is made up of multiple JLabels.
If it's not possible to resolve the issue without using a Layout Manager I will switch to BoxLayout, I was just hoping there would be a solution.

The problem is JScrollPanel needs the preferred size of the view component to determine when the view exceeds the scroll pane's viewable area.
The preferred size of a component is normally determined via the layout manager. While you can use setPreferredSize, it is typically discouraged and you will simply run into the same problem as the content exceeds what ever value you decide to set.
A better solution would be to use a LayoutManager or compound layout (using multiple layout managers over multiple containers) to achieve the result you desired...or write your own...

How to overlap panels in Java Swing?

I have a screen in my application. The layout of the screen is shown in the attached image file.
I have to add upto 5 labels in Panel1111. But, When I try to add labels in Panel1111, the Panel11 resizes and Panel12 shifts downwards to give space to Panel11.
I want to overlap content of Panel1111 on Panel12.
How can I achieve it?
Layout details:
Panel1 : BorderLayout
Panel11: OverLayLayout
Panel111: GridBagLayout

Using JLayeredPane. Go to Oracle Java website, and go through the tutorial: How to Use Layered Panes

Java's Layout Managers by default try to show all information that is inside them.
If you say you want two panels to overlap, this essentially means that the lower one cannot be seen fully, and also not interacted with in the hidden/overlapped part. Then, this part of the panel doesn't make sense any more. So you should probably rethink your GUI.
If you want it to overlap only at certain times, and the user can define when it should overlap and when not, then you'll need to handle that manually by using no Layout Manager at all, but position the elements yourself. Oracle provides some hints how to do that: http://docs.oracle.com/javase/tutorial/uiswing/layout/none.html.
In the end, you might end up writing your own, custom Layout Manager to handle the resizing of the panels.
Note: only the the layout of Panel 1 must be manually managed. The other panels can likely be handled by a LayoutManager again.

add()ing to a JPanel breaks its size

I have a JPanel identified by myPanel. I create a series of JButtons, and add() them to myPanel. At the end of my generating-and-adding loop, I call myPanel.validate(). The buttons show up.
The problem is the size of the panel is affected. No matter what Layout Manager I choose, the buttons are always added on the same line (even though there is more space beneath them).
I have tried setting myPanel's maximum size and setting its size after every add(). No matter what I do, after that validate(), the panel is blown up and my application's GUI is screwed.
Any ideas?

I create a series of JButtons, and add() them to myPanel... the buttons are always added on the same line (even though there is more space beneath them).
None of the default layout managers provide automatic wrapping. You need to specify how you want wrapping to occur. A GridLayout or a GridBagLayout can be used in these cases.
Or you can try the Wrap Layout which was written for this purpose.

i would firstly set a preferred size on the jpanel:
myPanel.setPreferredSize(new Dimension(X, Y));
this will tell your layout manager how to try to fit the contents within this dimension.
without seeing your source code, i can't add much more than that.

Question to pack() method

I'm building a GUI application, and within a JFrame i have 2 jcombobox's and a JPanel to view certain data. Now when i call the pack() methode in the main class it puts the two jcombobox'es next to my JPanel, which i dont want, because I want them North. Ofcourse I've tried to hard-code it in my code, but it doesn't work after I've called the pack() method.
Are there any alternatives to this method?

Only one component can be NORTH, so if you want both ComboBoxes to be NORTH you have to add them into a separate container. This separate container can then be put NORTH.
(Post the source for more exact help.)

All pack does is resize the Window (in this case JFrame) to its preferred size and the preferred sizes of its sub-components. To control the actual location of the sub-components relative to one another you need to use an appropriate LayoutManager.
You might want to check out the Using Layout Managers tutorial.

The pack() method just causes the layouting to happen, it has abolutely nothing to do with what is put where.
Most likely you're not using layout managers correctly. Show us your code and we can tell you waht exactly you're doing wrong.

You can avoid using pack by explicitly setting the frame size with setSize and setBounds. However, using pack is usually the preferred way as it leaves the frame layout manager in charge of the frame size.
That being said, the problem you are describing appears to be related to the correct use of a layout manager rather than the sizing of the frame. Have a look at the various layout managers for Swing and how to use them: http://download.oracle.com/docs/cd/E17409_01/javase/tutorial/uiswing/layout/using.html.

Can a layout manager spawn several JPanels?

I have to build a rather large form with many controls. The controls are divided in basic controls/settings and extended controls/settings. The user can decide if he wants to see only the basic or both basic and extended controls.
I've dropped all extended controls onto their own JPanel so that I can easily switch between the two views by showing or hiding this panel.
Currently I'm using GroupLayout and what happens is that the controls on different panels are not aligned:
Label aaa: Text field
Label a: Text field
Label aaaaaa: Text field
----------------------------
Label b: Text field
Label bbb: Text field
Label bb: Text field
Unfortunatly I found now way to "synchronize" the layouts of the two panels (except using AbsoluteLayout and fixed control coordinates)
Is there any way to achive this?
Is my whole design flawed?
EDIT: If it is possible I would like to keep the GroupLayout manager.

As far as I know, no Swing LayoutManager (from JRE or open source) can span several panels.
I am currently working on such a feature (which I called "layouts synchronization") for my DesignGridLayout project, but it is not something easy to implements (I have started about 2 weeks ago and I still don't see exactly if and when I will get to something interesting, but I still have high hope for it;-))
One option you could check would be to add all components to the same panel (with just one GroupLayout then) and hide/show them based on user's selection. Hopefully, GroupLayout will adapt the size to the situation (after calling pack()).
If GroupLayout behaves well, then it would just be a matter of calling pack() each time after user changes his selection to show/hide extended fields.
Else you would have to manually set the size of your panel every time the user changes his selection.

Probably the easiest (good) way to do it is to add all the components to the main panel. Set the subpanels to non-opaque, and add the also to the main panel. The main panel the needs optimised drawing to be switched off.
Another technique is to add a spacer component. To the bottom panel add a component in the same column as the labels which dynamically takes the width component of its various size methods from the top labels. Do the same in reverse to the top panel.

I think there is no way to do it with the standard layout managers. You'll probably have to write your own layout manager, but it shouldn't be too hard if you subclass GroupLayout.

You could use GridLayout instead of GroupLayout which will give you uniform spacing between the columns

If you want to keep them in separate panels with separate layouts:
Iterate over all of the labels that you add, and find the maximum preferred width of each.
Iterate a second time, and set the preferred size to that each label's preferred height, but the maximum width.

This is the explanation of th GridLayout. This will set every component to the size, you expect it. With the GridData object you can specify how the components are ordere.
Examples
(source: sun.com)