Everytime I click a button in my program, I add 5 new rows to the JPanel. Eventually, the rows overflow and I would like to add a JScrollPane so I can scroll down and see the new rows.
I know how to get it working for a TextArea but I can't seem to figure out how to make it work when I have a GridBagLayout. Below, I will attach the code for setting up my panels.
JPanel panelMain = new JPanel();
getContentPane().add(panelMain);
JPanel panelForm = new JPanel(new GridBagLayout());
panelMain.add(panelForm);
JScrollPane scrollpane = new JScrollPane(panelForm);
panelMain.add(scrollpane);
When I run, my code I get a box enclosing the GridBagLayout, but the scrollpane is nowhere to be seen.
JPanel panelMain = new JPanel();
getContentPane().add(panelMain);
You would typically add the scroll pane directly to the frame. There is no need for the "panelMain".
panelMain.add(panelForm);
That line is not needed. A component can only belong to a single parent. You later add "panelForm" to the scrollpane.
So the basic code would be:
JPanel panelForm = new JPanel(new GridBagLayout());
JScrollPane scrollpane = new JScrollPane(panelForm);
frame.add(scrollpane);
but the scrollpane is nowhere to be seen.
The scrollbars only appear when needed by default. Adding empty panels will not cause the scrollbar to be displayed. Click on your button a few times and add your child components to the "panelForm" using the appropriate GridBagConstraints. You will then need to use:
panelForm.revalidate();
panelForm.repaint();
The revalidate() causes the layout manager to be invoked so the scrollpane can determine is scrollbars are required or not.
Related
This seems like a simple thing to do, but I can't get it to work.
I have a BorderLayout. I want to use the top part for a title bar. I want to add a JPanel with labels, buttons and other components. However, the PAGE_START part of the border layout won't left align the panel. Here's the situation, with comments in where I've tried to set the alignment.
I noticed that when I don't add a panel to the border layout, and just write the JLabel straight in, it has left alignment by default.
This is not what I want, though, because I am planning on putting a BoxLayout.X_AXIS horizontally through the BorderLayout.PAGE_START title area. Seems to be a reasonable thing to do?
The Container pane argument to the static method is just the single panel on the main JFrame.
public static void addComponentsToPane(Container pane)
{
JLabel jlabel = new JLabel("I want to left align this inside a JPanel");
// Doesn't work: jlabel.setAlignmentX(Component.LEFT_ALIGNMENT);
JPanel jpanel = new JPanel();
//Doesn't work: jlabel.setAlignmentX(Component.LEFT_ALIGNMENT);
jpanel.add(jlabel);
pane.add(jpanel, BorderLayout.PAGE_START);
// Other parts of the BoxLayout (works fine)
JButton button = new JButton("Button 2 (CENTER)");
button.setPreferredSize(new Dimension(200, 100));
pane.add(button, BorderLayout.CENTER);
button = new JButton("Button 3 (LINE_START)");
pane.add(button, BorderLayout.LINE_START);
button = new JButton("Long-Named Button 4 (PAGE_END)");
pane.add(button, BorderLayout.PAGE_END);
button = new JButton("5 (LINE_END)");
pane.add(button, BorderLayout.LINE_END);
}
Even when I tell the panel to left align the label, it doesn't appear left aligned.
Does anyone know what I am doing wrong?
By default a JPanel uses a FlowLayout with "center" alignment.
if you want components "left" aligned, then you need to set the layout on the panel to use a FlowLayout with "left" alignment.
Read the FlowLayout API for the proper constructor to use to set the alignment.
Or you can also read the Swing tutorial on How to Use FlowLayut which gives the constructors and valid values to specify the alignment.
Somehow I don't the scrollpane to show up. What do I need to change?
bigP = new JLabel();
setLayout(new BorderLayout());
JPanel helper = new JPanel(new FlowLayout());
helper.add(bigP);
helper.setPreferredSize(new Dimension(500,600));
helper.add(new JScrollPane(bigP, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS));
picPane = new JPanel(new BorderLayout());
picPane.add(helper,BorderLayout.CENTER);
picPane.setMaximumSize(new Dimension(500, 600));
picPane.setVisible(true);
add(picPane, BorderLayout.CENTER);
After an image is chosen this line is called:
bigP.setIcon(img);
I figured out that I most certainly will need the helper-panel as the BorderLayout would only take one component (as far as I understood).
Unfortunately my scrollpane won't show up at all though the picture does.
helper.setPreferredSize(new Dimension(500,600));
Don't hardcode a preferred size. The panel will determine its own preferred size based on the components added to the panel.
JPanel helper = new JPanel(new FlowLayout());
helper.add(bigP);
sc = new JScrollPane(bigP,JScrollPane
Also a component can only have a single parent. In the above code you attempt to add "bigP" to "helper". But then in the next statement you add it to the scrollpane, so "bigP" is removed from the "helper" panel and will only appear in the scrollpane.
//pic.add(bigP,BorderLayout.CENTER);
pic.add(helper,BorderLayout.CENTER);
Also you never add the scroll pane to the "pic" panel. The code should be:
//pic.add(bigP,BorderLayout.CENTER);
//pic.add(helper,BorderLayout.CENTER);
pic.add(sc, BorderLayout.CENTER);
So now you should have a structure that looks like:
- pic
- sc
- bigP
It would also help if you use more descriptive names so everybody knows what those variable are.
I have a JFrame which contains a JSplitPane in a JScrollPane (so the user can scroll if the window is to big). The JSplitPane contains a JTabbedPane as the top component and graphics as the bottom component.
Now i want to read a .csv und display it in my JTabbedPane. I can scroll through the list with a second JScrollPane. Here comes the problem, when i import the .csv in my programm, the first JScrollPane seems not to notice that there is a second JScrollPane for scrolling the list and then my window gets a lot of free space to scroll.
JFrame frame = new JFrame();
JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP, JTabbedPane.WRAP_TAB_LAYOUT);
JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
splitPane.setTopComponent(tabbedPane);
splitPane.setBottomComponent(graphics());
JScrollPane scrollPane = new JScrollPane(splitPane);
frame.add(scrollPane);
frame.setVisible(true);
When i import the .csv I add a new JPanel to the tabbedPane. The JPanel contains a list from the data from the .csv
JPanel panel = new JPanel();
JScrollPane scrollPane = new JScrollPane(panel);
// here comes the code for the list
tabbedPane.add(scrollPane);
I hope you understand my problem, it is hard to explain.
Edit: Pictures from before and after importing the .csv may help you to understand.
Get rid of the first scroll pane. Add the split pane directly to the CENTER of the BorderLayout used by the frame. As the frame resizes all the space will be allocated to the split pane.
You can then use:
splitPane.setResizeWeight(1.0);
Now all the extra space will go to the second component as the frame is resized. Therefore the scrollbar for that component will appear/disappear as required.
I'm trying to insert a new panel into another panel in runtime everytime I press a button. My problem is the original panel runs out of space and I can't see the new panels I'm adding.
What I've tried so far:
Using scrollpane for vertical scrolling with no success.
Using flowlayout-no luck. Tried disabling horizontal scrolling-keep pushing the new panel to the right (can't get to it because there is no scrolling).
Tried using borderlayout-no luck.
testpanel t = new testpanel();
t.setVisible(true);
this.jPanel15.add(t);
this.jPanel15.validate();
this.jPanel15.repaint();
This code suppose to insert the t panel into jpanel15.
With flowlayout it pushes the t panel downwards just like I want it to but with no vertical scroll.
PS: I'm using netbeans in order to create my GUI.
My problem is the original panel runs out of space and I cant see the new panels i'm adding. Tried using scrollpane for vertical scrolling with no success.
A FlowLayout adds components horizontally, not vertically so you will never see vertical scrollbars. Instead you can try the Wrap Layout.
The basic code to create the scrollpane would be:
JPanel main = new JPanel( new WrapLayout() );
JScrollPane scrollPane = new JScrollPane( main );
frame.add(scrollPane);
Then when you dynamically add components to the main panel you would do:
main.add(...);
main.revalidate();
main.repaint(); // sometimes needed
Use JScrollPane instead of the (outer) JPanel
Or have a BorderLayout for the JPanel, put in a JScrollPane at BorderLayout.CENTER as the only control. The JScrollPane takes a regular JPanel as view.
In any case you will then add the control to the JScrollPane. Suppose your JScrollPane variable is spn, your control to add is ctrl:
// Creation of the JScrollPane: Make the view a panel, having a BoxLayout manager for the Y-axis
JPanel view = new JPanel( );
view.setLayout( new BoxLayout( view, BoxLayout.Y_AXIS ) );
JScrollPane spn = new JScrollPane( view );
// The component you wish to add to the JScrollPane
Component ctrl = ...;
// Set the alignment (there's also RIGHT_ALIGNMENT and CENTER_ALIGNMENT)
ctrl.setAlignmentX( Component.LEFT_ALIGNMENT );
// Adding the component to the JScrollPane
JPanel pnl = (JPanel) spn.getViewport( ).getView( );
pnl.add( ctrl );
pnl.revalidate( );
pnl.repaint( );
spn.revalidate( );
I have a really weird problem with a JScrollPane and a BorderLayout. For short explaination: i have a JTable which is inside the JScrollPane and this is with a JPanel and the JTableHeader on a JTabbedPane. Very Simple Layout. If i add just the JTable to my JPanel, the buttons are working. If i add the JScrollPane, the Buttons are not working anymore, so i cant click them! The ActionLister is never reached and i cant see the click-animation.
Some Sample code to explain:
d_pane = new JPanel();
d_button = new JPanel();
d_pane.add(table.getTableHeader(), BorderLayout.PAGE_START);
dl_scroll = new JScrollPane(table);
d_pane.add(dl_scroll, BorderLayout.CENTER);
// d_button is ridLayouted with 3 Buttons in there
d_pane.add(d_button, BorderLayout.PAGE_END);
1) The JScrollPane takes care of the table header itself. Don't add it to the pane.
2) the button does not seem to get the mouse events, probably because another component is above it - do you have other components/code in the setup?