Develop Reference

Swing JScrollPane resizing to fit the viewport panel

I tried a lot of layout managers but none could solve my problem:
I want the items in a scrollPane to keep their size (preferred or minimum) and not being resized (reduced) to fit the viewport Panel. Since if it is a JTextArea, and if the text area has blank space and it is bigger then the viewport, it would reduce it so the blank text area won't be shown. I want the blank text area to be shown for appearance issues.
Im stacking one item after another using BoxLayout, and it seems to me that for text areas the setMinimum method fails.
If the text area has blank space, then the scrollbar of the ScrollPane won't appear, instead it only appears it there are no blank space left.
Any solution?
JScrollPane materialPane = new FScrollPane();
this.materialPaneView = new TPanel();
this.materialPaneView.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
this.materialPaneView.setLayout(new BoxLayout(this.materialPaneView, BoxLayout.Y_AXIS));
materialPane.setViewportView(materialPaneView);
materialPane.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/2)));
for(Material mat: this.unit.getMaterial()){
this.addMaterial(mat);
}
centerPanel.add(sectionPane);
centerPanel.add(exercisePane);
centerPanel.add(materialPane);
this.add(upperPanel, BorderLayout.NORTH);
this.add(centerPanel, BorderLayout.CENTER);
public void addMaterial(Material mat){
JTextField matName = new JTextField(30);
JPanel fieldButtonPanel = new TPanel();
fieldButtonPanel.setLayout(new GridLayout(1,2));
JPanel fieldPanel = new TPanel(new FlowLayout(FlowLayout.LEFT));
JPanel deleteMatButtonPanel = new TPanel(new FlowLayout(FlowLayout.RIGHT));
matName.setText(mat.getName());
matName.setMaximumSize(new Dimension(FFont.def.getSize()*20, 30));
fieldPanel.add(matName);
JButton deleteMat = new JButton("Delete Material");
deleteMatButtonPanel.add(deleteMat);
fieldButtonPanel.add(fieldPanel);
fieldButtonPanel.add(deleteMatButtonPanel);
fieldButtonPanel.setAlignmentX(LEFT_ALIGNMENT);
JTextArea matText = new FTextArea(mat.getDesc(), (int)(WIDTH*0.95), (int)(HEIGHT/3.4));
matText.setMinimumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.5)));
/*matText.setMaximumSize(new Dimension((int)(WIDTH*0.95), (int)(HEIGHT/3.4)));*/
matText.setText(mat.getDesc());
matText.setAlignmentX(LEFT_ALIGNMENT);
this.materialPaneView.add(fieldButtonPanel);
this.materialPaneView.add(matText);
matName.addActionListener(new ActionListener(){
#Override
public void actionPerformed(ActionEvent e) {
mat.setName(matName.getText());
}
});
HEIGHT and WIDTH are constants, and TPanel FScrollPane are my predefined transparent panels. The BoxLayout panel is the viewport of a scrollPane, and still, it would resize the text areas.

I am not sure i get what you are asking for so please tell me if i totally missed the point...
As far as i know the Viewport size is controlled by the component inside the JScrollPane and the JScrollPane size wont change no matter what happens to the viewport.
You either want to:
A) Resize the JScrollPane to the same size as it's content.
I would implement listeners to look for the content size change and resize the ScrollPane accordingly but you need to pay attention to resize the whole Hierarchy too.
B) You want to resize the viewport so that it fits in the JScrollPane? Y'know without scrollbars.
I had this problem and fixed it by using a ScrollablePanel component. Check this answer, follow the link to download the .class and use it to use a JPanel that resizes to fit the ScrollPane.
Those arent very detailed answers but i will need more information about what you are trying to do before expanding on it. And your code isnt complete, always share a code that we can CTRL+C/V and readily verify the problem in our end.

JLabel wont change Width

I'm programming right now a Chomp Game for Uni. Everything works fine but the Label at the bottom. Its background is supposed to fill out the entire bottom. In the attachment you can see how it instead looks now. I tried setting the minimum and the preferred size of the label. The Height is changing but the width just stays adjusted to the text. How can I change that?
Note: The snippet only contains the setting up of the Frame and Panels in a custom method and not the main class.
private void init()
{
JFrame fenster = new JFrame();
this.spielfeld = new SpielfeldPanel(M, N);
this.anzeige = new SpielerAnzeigeLabel(this.spieler);
JPanel panel = new JPanel();
BoxLayout boxlayout = new BoxLayout(panel,BoxLayout.Y_AXIS);
panel.setLayout(boxlayout);
fenster.setTitle("Chomp");
fenster.setSize(1000,700);
panel.setPreferredSize(new Dimension(1000, 60));
Dimension d = new Dimension(getPreferredSize());
panel.setMinimumSize(d);
panel.add(spielfeld);
panel.add(anzeige);
fenster.add(panel);
this.spielfeld.setVisible(true);
this.anzeige.setVisible(true);
panel.setVisible(true);
fenster.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

A BoxLayout respects the width of the component to the label is displayed at its preferred width/height.
A JFrame uses a BorderLayout by default. So just add the label to the frame independently of the panel:
//panel.add(anzeige);
//fenster.add(panel);
fenster.add(panel, BorderLayout.CENTER);
fenster.add(anzeige, BorderLayout.PAGE_END);
The PAGE_END constraint respects the height but makes the width equal to the space available. Read the section from the Swing tutorial on How to Use BorderLayout for more information and examples.

How can you add several elements to a JScrollPane

So I am trying to add more than one element to a JScrollPane element but so far I haven't been able to pull it of.
I can make it so that the first element shows up ,which in my case is a picture. But after adding in an extra panel to the JScrollPane ,the first element disappears and even the second element ,the new panel , doesnt show on my JScrollPane.
JFrame scherm = new JFrame("t?");
scherm.setVisible(true);
scherm.setSize(300, 300);
scherm.setLocationRelativeTo(null);
scherm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//
String path = "C:\\Users\\Bernard\\Documents\\Paradox Interactive\\Crusader Kings II\\mod\\viking\\map\\provinces.bmp";
Image image = ImageIO.read(new File(path));
ImageIcon icon = new ImageIcon(image);
JLabel label = new JLabel(icon);
JScrollPane scroll = new JScrollPane(label);
JPanel paneel2= new JPanel();
paneel2.setSize(new Dimension(400,400));
scroll.getViewport().add(paneel2,null);
scherm.add(scroll);
Thank you for your time!

By doing this:
scroll.getViewport().add(paneel2,null);
You're trying to add a component to the scroll pane's JViewPort shown in the picture below:
This makes no sense. As stated in How to Use Scroll Panes trial:
A
JScrollPane
provides a scrollable view of a component.
This single component is the view port's view. So if you want to have more than a single component in your scroll pane you must to wrap all those components in a lightweight component such as JPanel and set this one as the scroll pane's view port view:
JPanel content = new JPanel();
content.add(label);
content.add(paneel2);
scroll.setViewportView(content);

GridLayout hgap vgap "not working" on JPanel?

JPanel grid = new JPanel();
GridLayout layout = new GridLayout (6,7,0,0);
grid.setLayout (layout);
slot = new ImageIcon ("");
for (int x = 0; x < 42; ++x)
{
slotbtn = new JButton(slot);
slotbtn.setContentAreaFilled (false);
//slotbtn.setBorderPainted (false);
slotbtn.setBorder (BorderFactory.createEmptyBorder (0,0,0,0));
slotbtn.setFocusPainted (false);
grid.add(slotbtn);
}
This is the output I get:
I am creating a 6x7 grid. The output I need is for there to be no space in between the rows and columns, everything should be compressed together. I tried pack and it didn't work. What am I doing wrong?
-- I tried FlowLayout but I had to resize the frame and I have other buttons on the frame so I don't think I'd prefer resizing it to make the buttons fit in their proper places.
-- I placed this JPanel inside another jpanel(which uses borderlayout and contains two other panels) and I placed it at the center, the two other panels North and South.

this issue because you divide the grid (the whole size of grid) to 7*6 so if you re-size the window you will see this gaps changed so if you wan't to remove this gab
calculate the size of the window (ex: width = 7* width of your image , hight = 6*hight of your mage)
or re-size your image

JButton employs a margin property to provide additional padding to the content area of the button, you could try using...
slotbtn.setMargin(new Insets(0, 0, 0, 0));
I would also try using something like slotbtn.setBorder(new LineBorder(Color.RED)); to determine if the spacing is from the button, icon or layout
GridLayout will also provide each cell with equal amount of space, based on the available space to the container, this means that the cell may increase beyond the size of the icon.
While a little more work, GridBagLayout would (if configured properly) honour the preferred size of each component.
Have a look at How to use GridBagLayout for more ideas.

I get no margins using your code, with any image I use. Check your image. And maybe post a runnable example replicating the problem. Maybe there's something going on you're not showing us. I'd start by checking the image for margins. Check it against this. If it still has margins, than its your image. Also, Don't set the size to anything! You may be stretching the panel unnecessarily, which will cause the gaps. Also if there an of your other panels are larger than the grip panel, it will also cause it to stretch. But take all your set(Xxx)sizes out and see what happens. Just pack()
import java.awt.GridLayout;
import javax.swing.*;
public class TestButtonGrid {
public TestButtonGrid() {
ImageIcon icon = new ImageIcon(getClass().getResource("/resources/stackoverflow3.png"));
JPanel panel = new JPanel(new GridLayout(6, 7));
for (int i = 0; i < 42; i++) {
JButton slotbtn = new JButton(icon);
slotbtn.setContentAreaFilled(false);
//slotbtn.setBorderPainted (false);
slotbtn.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
slotbtn.setFocusPainted(false);
panel.add(slotbtn);
}
JFrame frame = new JFrame();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
new TestButtonGrid();
}
}

java use size of JPanel to size components

Is it possible to use the size of a JPanel to set the size of components inside the JPanel? When I try to use getHeight() or getWidth() on the JPanel it always returns 0. I know that it gets it's size once the JFrame is packed, but how would one go about using the dimensions of the JPanel and applying it to a component inside it? Something like this
JPanel panel = new JPanel();
JLabel label = new JLabel();
label.setWidth(panel.getWidth());
panel.add(label);
EDIT:
See sample code below. What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
public class Main extends JFrame{
public Main(){
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.PAGE_AXIS));
panel.setBorder(BorderFactory.createLineBorder(Color.blue));
JLabel label = new JLabel();
label.setBorder(BorderFactory.createLineBorder(Color.red));
label.setText("label1");
label.setMinimumSize(panel.getPreferredSize());
label.setPreferredSize(panel.getPreferredSize());
panel.add(label);
add(panel);
setDefaultCloseOperation(EXIT_ON_CLOSE);
pack();
setSize(500,500);
setVisible(true);
}
public static void main(String[] args)
{
new Main();
}
}

Is it possible to use the size of a JPanel to set the size of components inside the JPanel?
This is the job of the layout manager.
When I try to use getHeight() or getWidth() on the JPanel it always returns 0
When the layout manager is invoked the Container will have a valid size so the layout manager can do its job properly.
There is no reason for you to be playing with sizes. Leave it to the layout managers to do their jobs.
Update:
What should I do if I want my Jlabel to be as wide as my JPanel? Is it wrong to use boxlayout in this case?
The BoxLayout attempts to respect the minimum/maximum size of the component. In you case you should be able to do something like:
JLabel label new JLabel("some text");
label.setBorder(....);
Dimension d = label.getPreferredSize();
d.width = 32767;
label.setMaximumSize( d );
Or maybe a simpler approach is to start with a BorderLayout. You can add the label to the NORTH. Then create another panel and add it to the CENTER.

Of course you can, but be careful that the result depends on the layout manager of your JPanel and on the number of its child components.

Setting the width ignores resizing. LayoutManagers typically ask components for their preferred widths and heights, and expand / contract items to maintain a visually appealing position after the frame has been resized. So, your best option is to leverage the layout manager and report a "preferred width".
You can use setPreferredWidth(...); but, if your preferred width is to change over the run of the program (due to window size changes), you will need to listen to the panel in question and update your button's preferred width as the panel's preferred width changes (this assumes it changes, which might not be true).