I'm working on my first Swing application and I'm having a layout problem concerning a dialog window I created for my users to enter values in certain fields. Because the number of fields displayed varies based on a user choice, I use a JScrollPane in my dialog, setting its viewport to a panel to which I add my field components.
For every field to be displayed, I create and add three components:
"field name" label
Field component (usually a JTextField, but it also could be a JComboBox or a JDateChooser control)
"field type" label
i.e.
namelabel: |____| (String)
name2label: |__| (Number)
All three of these components can be of varying lengths, so my challenge has been to find a tidy way to layout these components. What I've been doing is setting the layout manager for the main pane to be a BoxLayout that uses the y-axis (i.e. it lays out components vertically). I then create a pane for each field, set the layout manager for that pane then add all three field components to that pane. I've tried both a FlowLayout and BoxLayout for the individual panes, and I've had issues with both of those layout managers.
I set the FlowLayout manager to use a left justification, but due to the varying lengths of the components, this led to a crooked-column layout. I set the BoxLayout to use the X-axis (i.e. lay things out horizontally) but the consequent centering of the components resulted in a vast spacing between each component. And prior to using individual panes, I tried to use GridLayout but I was never able to get it to honour my three-column requirement, causing the fields to be split across rows. I also looked briefly at an article about the GroupLayout manager but it seemed intimidating :)
Does anyone have any suggestions on how to layout a varying number of rows of three components of varying length within a JScrollPane in a neat, compact way? Thanks in advance...
Sheldon R.
It's a common problem: MiGLayout is a good choice. Alternatively, BoxLayout is illustrated here, and Group Layout is shown here.
Also take a look at SpringLayout.
Update: My three-column idea didn't work out for the same reason most of my other ideas didn't work i.e. BoxLayout, like most of the layout managers, tends to expand the component to fill as much space as it can, so my fields were being rendered as enormous :)
So I bit the bullet and tried to figure out GroupLayout, based on the example shown by #trashgod being similar to what I was trying to achieve. After figuring out how to do what I wanted in the GroupLayout way, I initially ran into the same expanding-field issue. Then the Oracle GroupLayout tutorial showed me how to keep the components from being resized i.e. using the four-argument version of the addcomponent method: addComponent(field, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE) I tried that and it worked like a charm. Thanks again, #trashcan for pointing me in the right direction, and thanks to everyone else who chimed in with ideas...
Sheldon R.
Related
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...
I'm pretty new to programming Java based GUI applications. Here's what I have in mind, I want to divide the window into two areas.
The first are contains buttons (or a list), and based on which button was clicked, or which item was selected, the second area changes. (finite number of buttons)
Something like this:
I can think of many ways to do this, but I am not sure what is the best practice. Do I have several invisible panels and make only 1 panel visible at a time, or do I change the ordering (bring panel x to front), or is there some other way?
Appreciate any help I receive!! Thanks in advance!
Although this is a primarily opinion-based answer I'd go with a Nested Layout approach:
Main panel with BorderLayout. Or you can use the frame's content pane which already has BorderLayout as default layout manager.
Left panel with BoxLayout (or GridBagLayout).
Right panel with CardLayout.
Note: Buttons in the left panel should switch right panels cards.
See Lesson: Layoing Out Components within a Container tutorial.
For complex GUIs you have also third-party layout managers available, listed in this answer:
MiG Layout
DesignGridLayout
FormLayout
I am trying to create a GUI for a program with an undefined number of rows but stay with two columns. Currently the only way I can get it to look how I want is using FlowLayout but the window of course needs to be smaller than desired. It needs to happen within one panel as well because it is being added to a tabbed pane.
What would be the best layout manager to solve the problem that is in the JDK? Or would just kind of brute forcing it with AbsoluteLayout be the best approach (as the user shouldn't really be resizing the window)?
I have attached the desired appearance.
Thanks for any help in advance.
Several layouts can do what you want. I'd suggest GridLayout (easy to use, but columns will be equal width) or GridBagLayout (harder to use, but you have lots of control). You could also use a BorderLayout and put all the fields in a sub-panel on the WEST and all the drop-downs in a sub-panel on the EAST. The difficulty with that is ensuring that the rows have the same height, since they won't be constrained by the layout itself.
The best thing to do would be to go through the Java tutorial on layouts and get up to speed on what the various layout managers can do.
Also, since you're using Swing, you could just use a JTable (as Gilbert Le Blanc suggests in his comment).
I'd like to make a login bar for an application and I can't figure out how to organize a series of JLabels and JTextFields such that they are organized in a horizontal grid without these same components being resized to fit each cell. I also want to make sure that the group of components isn't resized below a certain width. How can this be achieved?
Edit: Thanks for the answers everyone. I'll have a look at MigLayout and SpringLayout later. Due to time constraints I'm going to have to make do with Visual Editor and use a null layout. The component placement and dimensions have to be adjusted by hand but at least they stay put. Here's a picture showing what I wanted to do.
bar http://img145.imageshack.us/img145/7356/bargw.png
Use MigLayout as your layout manager, it's extremely flexible, and supports what you're asking quite easily. You can set size constraints. If you need any further help, post some example code using Swing and MigLayout which shows what you're trying to do, and then I'll advise you on how to do what you want to achieve.
You probably want some additional cells which 'grow' to fill the remaining space. This can be achieved with column constraints, by inserting 'push' between the columns (specified by [..]) to expand the gap. You don't need any placeholder components in this case. (i.e., [pref!]10px[40px::]push[pref!]10px[40px::])
You have to use different layout. FlowLayout or BoxLayout will work in your case, but I would suggest MigLayout simply because it will cover all your needs and replace all others .
Check out the section from the Swing tutorial on Using Layout Managers.
The SpringLayout has an example that does exaclty this.
The GridBagLayout is more difficult to use but also support row/column type layout.
Finally, you can still use a GridLayout. Just add the text fields to a JPanel first, then the panel will grow but the text field won't.
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)