I am learning to use swing so please bear with me. Have a look at the attached screenshot:
These are JLabels within a JLabel within a JFrame. I would like to move these inner JLabel (which are randomly generated in size and color at runtime) to the very bottom as though they were books on a shelf. I know about Layout managers, though I can't quite seem to find the proper one to do what I want. This screenshot shows the result of specifying none, thus it should default to FlowLayout.
The inner JLabels are just .add()ed without any placement done. SetLocation appears to do nothing whatsoever.
Can you help me out?
If I were you I'd add put those JLabels inside of a JPanel with a boxlayout then align that with a border layout. Here is some code to help you out:
JLabel outer = new JLabel();
outer.setLayout(new BorderLayout(0,0));
/** Add inner JLabels here. The other you add them is the order they will appear from to right**/
JPanel bookshelf = new JPanel();
bookshelf.setLayout(new BoxLayout(toolbar, BoxLayout.X_AXIS));
//Add your jlabels to the bookshelf
outer.add(bookshelf, BorderLayout.SOUTH);
Here is a great tutorial on layout managers.
Also here is a UI I designed which is similar to what I think you want.
Hope this helps you out.
Can i combine Java layouts in same JPanel. I'm stuck with with placing my components on JPanel. It shoudl be like this: JLabel, JButton, JButton , JLabel and new line and same. I used BorderLayout but it wont go to the next row, keep adding components to same row and I need a new row. Ideal sit combined with cardlayout or some other good solution.
EDIT: Solved with GridLayout (0,4) It will do the job till i learn to use GridBaglayout. Thank you for trying to help me.
Yes you can combine layouts.
Using a JPanel you are able to embed other JPanels:
JPanel back = new JPanel(new BorderLayout());
JPanel rows = new JPabel(new GridLayout(3,3));
back.add(rows, BorderLayout.CENTER);
Without seeing your code though it's difficult to know exactly what you are trying to achieve!
Yes you can combine java layouts.
A common pattern I use is BorderLayout first on a frame. The central component expands out, while the other components shrink in. Inside these panels I might have a Flowlayout to show buttons evenly spaced horizontally on top.
Another common approach for forms is using a Gridbaglayout, then adding all the form elements at gridX and gridY positions. I then later can stretch and teak these cells using other constraints in the Gridbaglayout repetoire.
Can you add a screenshot so that we can see what you want to do?
I have a panel derived from JPanel. I have a custom control derived from JLabel. I am attempting to center this custom JLabel on my panel.
The only way I know to do this that will work is to use the a null layout (setLayout(null)) and then calculate the custom JLabel's setLocation() point so that it's in the right spot.
The custom JLabel is physically moved from one panel to this panel in this app and I believe the location previously set in setLocation is affecting things. However when I set it to (0,0) the component goes up into the upper left corner.
BorderLayout doesn't work because when only 1 component is provided and placed into BorderLayout.CENTER, the central section expands to fill all of the space.
An example I cut and pasted from another site used BoxLayout and component.setAlignmentX(Component.CENTER_ALIGNMENT). This didn't work either.
Another answer mentioned overriding the panel's getInset() function (I think that's what it was called), but that proved to be a dead end.
So far I'm working with a panel with a GridBagLayout layout and I include a GridBagConstraints object when I insert the custom JLabel into my panel. This is inefficient, though. Is there a better way to center the JLabel in my JPanel?
Set GridBagLayout for JPanel, put JLabel without any GridBagConstraints to the JPanel, JLabel will be centered
example
import java.awt.*;
import javax.swing.*;
public class CenteredJLabel {
private JFrame frame = new JFrame("Test");
private JPanel panel = new JPanel();
private JLabel label = new JLabel("CenteredJLabel");
public CenteredJLabel() {
panel.setLayout(new GridBagLayout());
panel.add(label);
panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.add(panel);
frame.setSize(400, 300);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
CenteredJLabel centeredJLabel = new CenteredJLabel();
}
});
}
}
Supose your JLabel is called label, then use:
label.setHorizontalAlignment(JLabel.CENTER);
Forget all the LayoutManagers in the Java Standard Library and use MigLayout. In my experience it's much easier to work with an usually does exactly what you expect it to do.
Here's how to accomplish what you're after using MigLayout.
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import net.miginfocom.swing.MigLayout;
public class Test
{
public static void main( String[] args )
{
JFrame frame = new JFrame( );
JPanel panel = new JPanel( );
// use MigLayout
panel.setLayout( new MigLayout( ) );
// add the panel to the frame
frame.add( panel );
// create the label
JLabel label = new JLabel( "Text" );
// give the label MigLayout constraints
panel.add( label, "push, align center" );
// show the frame
frame.setSize( 400, 400 );
frame.setVisible( true );
}
}
Most of that is just boilerplate. The key is the layout constraint: "push, align center":
align center tells MigLayout to place the JLabel in the center of its grid cell.
push tells MigLayout to expand the grid cell to fill available space.
BoxLayout is the way to go. If you set up a X_AXIS BoxLayout, try adding horizontal glues before and after the component:
panel.add(Box.createHorizontalGlue());
panel.add(label);
panel.add(Box.createHorizontalGlue());
I don't like the answers here.
I've never seen a valid use of a GridBagLayout ever in my career. Not saying there isn't one, just saying I haven't seen [a valid] one, and there might be correlation there. Moreover, adding a single JLabel to the middle of a Container might make it center for demonstrational purposes, but you're going to have a lot harder of a time later on if you try to continue to work with that over some other layouts.
I do like the suggestion about the BoxLayout, because that is actually a great way to do it. That said, that answer is only part of the puzzle, hence why I'm dredging up a 7 year old question.
My 'Answer'
Really there is no short answer to your question. There is an exact answer to your question based on what you asked, but StackOverflow is about a community learning from each other, and I suspect you're trying to learn how to use layouts in general (or you were 7 years ago) and telling you to type a combination of keys to do exactly your demo case is not going to teach you the answer.
I'm going to try not to explain any layouts that you can't web-search the answer for on your own (with a link to the Oracle tutorial at the end, because I think it explains the different layouts fairly well).
BoxLayout
BoxLayout is one way to do it, and there is already a code snippet to demo it above so I won't provide one. I'll expand on it to say that, just as mentioned, that only answers your question exactly, but doesn't really teach you anything. Glue, as the BoxLayout refers to it, basically gives you an equal amount of remaining real-estate between all the 'glue' currently in the Container. So, if you were to do something like
panel.add(Box.createHorizontalGlue());
panel.add(label);
panel.add(Box.createHorizontalGlue());
panel.add(otherLabel);
You would find that your JLabel is no longer centered, because the 'glue' is only the remaining real-estate left, after two JLabels were added to the Container which will be equally divided between the two 'slots' (two calls to Container#add(Component) with a glue parameter) in theContainer`.
BorderLayout
BorderLayout is another way to go about this. BorderLayout is broken down into 5 regions. BorderLayout#CENTER, as you might guess, is the center region. The important note about this layout and how it centers things is how it obeys sizes of the Component that is in the center. That I won't detail though; the Oracle tutorial at the end covers it well enough if you're interested, I think.
Worth Noting
I suppose you could use a GridLayout, but it's a more simple way to do it over a GridBagLayout, which I already said even that I think is not a good approach. So I won't detail this one either.
The Point of it All
Now all that said, I think all LayoutManagers are worth a look. Just like anything else with relation to programming - use the tool that fits the job. Don't just assume because you used X layout before, that you should always use X layout and no other layout is viable. Figure out what you want your display to look like, and how you think it should behave with respect to resizing components, and then pick what you think would work best.
Another dual meaning of picking the right tool, is that you don't have to just fit all of your components into one single Container and make one layout do everything. There is nothing stopping you (and I strongly encourage you to) use multiple Containers and group them all together. Control each Container with a layout that is appropriate for that section of the display, and a different layout for a different Container.
Important!!
The reason why this is very important is because each layout has rules and things that they obey, and other things that they respect, and then others that are effectively ignored (i.e. preferred, maximum, and minimum sizes, for instance). If you use different layouts [correctly], you will find your display accepts dynamically being resized while still obeying the shape that you wanted it to hold. This is a very important key difference between doing it the right way, and just settling with GridBagLayout.
JPanel outer = new JPanel(new BorderLayout());
JPanel centerPanel = new JPanel();
centerPanel.setLayout(new BoxLayout(centerPanel, BoxLayout.PAGE_AXIS));
JPanel southPanel = new JPanel(new CardLayout());
outer.add(centerPanel, BorderLayout.CENTER);
outer.add(southPanel, BorderLayout.SOUTH);
Figure out what is appropriate to your scenario, and go with that. There is no one-size-fits-all unless you want something overly cumbersome and made redundant by other layouts (i.e. GridBagLayout).
Oracle's Tutorial
If you've made it this far, then I think you're looking for as much information as you can get. In which case, I strongly encourage you to read Oracle's tutorial on layout managers because it lays out general details of them all very well: https://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
Use this.
labelName.setHorizontalAlignment(SwingConstants.CENTER);
or
labelName.setHorizontalAlignment(JPanel.CENTER);
Both of them must work.
Do like this instead of libraries and layouts :
JLabel jlabel = new JLabel("Label Text", SwingConstants.CENTER);
Make sure to import javax.swing.SwingConstants INTERFACE , BUT DO NOT IMPLEMENT IT. It contains only constants and no methods.
Put the JLabel in a JPanel or else it will come at the center of the JFrame or JWindow (your top level container).
I'm getting back into swing after not doing it for a while.
What's the best way to have fixed sized button stay in the center , bottom of my window?
If I use Borderlayout.south it makes the button too wide. I can't remember the trick
There are generally two ways to handle this.
Nesting, I.e. Create a panel with border layout. Create another panel with flow layout to add your button to. Put the second panel in the south of the first panel
Use a more sophisticated layout such as GridBagLayout or MiG Layout
Look into using MigLayout. It's incredibly handy using Swing.
int buttonWidth = 100;
int buttonHeight = 50;
button.setPreferredSize(new Dimension(buttonWidth, buttonHeight));
this.setLayout(new MigLayout("insets 0"));
this.add(button, "pos 50%-" + buttonWidth/2 + " 100%-" + buttonHeight);
There might be an easier way with a core layout manager, or even an easier way with MigLayout, but that would be the way I would approach it at first.
Another alternative would be to use a null layout and setBounds whenever the parent panel's size changes. Most Swing programmers would advise against a null layout, in which case you could look at BoxLayout. It's entirely up to you, but I find MigLayout indispensable.
I'm building a grid filled with labels. One of them contains html-text and should resize to maximum format and be scrollable. I found how to add a JScrollPane but it stays one line height, I just can't find how to resize it even when I give it a size of 400x400 ...
Removing getViewport() gives the same result.
JPanel grid = new JPanel(new GridLayout(1,2));
// first cell of the grid
grid.add(new JLabel("title"));
// second cell of the grid, this should be the scrollable one
JScrollPane scroll = new JScrollPane();
scroll.getViewport().setSize(400, 400);
scroll.getViewport().add(new JLabel("<html>long<br>html<br>text</html>"));
grid.add(scrollVersion, BorderLayout.CENTER);
Any ideas ?
Thanks a lot ...
GridLayout does not respect preferred size of the components which it lays out. It aims to make all grid cells the same size. An alternative is to use GridBagLayout, however I personally would recommend ZoneLayout which (in my opinion) is simpler, just as powerful, and much more intuitive. With the cheatsheet you can't go wrong.
As a side note, BorderLayout.CENTER is a constraint used for BorderLayout and is not compatible with GridLayout. When components are added to the owner of a GridLayout, you need not provide constraints. Components are added left to right starting at the top left corner cell using GridLayout.
Replace your GridLayout with a GridBagLayout. With the correct set of constraints, it should work like a charm. And obviously, take a look at some examples, as GridBagLayout seems quite complex, but is rather simple with some examples.
All cells of the GridLayout are designed to have the same size, so if you want one to be bigger than teh othes you must use another LayoutManager, like the GridBagLayout that Riduel suggest.
Also if your JLabel is going to have more than one line i suggest you to replace it by an uneditable JTextPane o JTextArea