I'm building a Swing application in Java using NetBeans and I have a problem with layout. My main frame contains a JScrollPane which contains a JPanel called contentPanel which in turn contains a JPanel called listPanel. The listPanel is empty when the program starts, but when the user interacts with the program an unpredictable number of smaller JPanels are added to it. I've used the NetBeans GUI-builder to snap the top edge of listPanel to the top of contentPanel, and the same with the bottom edges.
The problem I have is that when more components are added to listPanel the vertical scrollbar doesen't appear on my scrollpane. The verticalScrollBarPolicy of my scrollpane is set to AS_NEEDED and its viewportView is set to contentPanel. What I think I need to do is to make contentPanel grow when more items are added to listPanel.
The problem I have is that when more components are added to listPanel the vertical scrollbar doesen't appear on my scrollpane.
The scrollbar will appear when the preferred size of the component added to the scrollpane is greater than the size of the scrollpane. When you add components dynamically you need to tell the scrollpane something has changed. So you basic code should be:
panel.add( subPanel );
panel.revalidate();
Or, because you are adding a panel to the sub panel, you may need to revalidate the scrollpane (I don't remember):
panel.add( subPanel );
scrollPane.revalidate();
The key is the revalidate() which tell the layout manager to recalculate its size.
Use a different LayoutManager. One that will allow for vertical growth like BoxLayout. Also remember that you can use multiple layouts and nest them inside of each other for different effects.
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I want to make a chat history in java swing.
I have a JScrollPane. I append dinamic multiple JPanels in him.
I use BoxLayout but I have a problem:
- When appending the first JPanel it are height 100% of JScrollPane.
- When appending the second JPanel, both are height 50% of total JScrollPane.
I want to make each JPanel have fixed height (40px).
What layout should I use or what should I do?
First off, I'd consider using a JList and not a grid of JPanels.
Your JList cell may easily display what looks like a JPanel view by simply using the right renderer.
And you'd lesson GUI override doing this.
If you must use JPanels, I'd put them in a GridLayout or BoxLayout container (JPanel)
Add this container to a BorderLayout using container (JPanel), to its BorderLayout.PAGE_START position
And then add this final container to the JScrollPane's viewport.
I have a JPanel inside of a JScrollPane which is nested inside some other containers. My JPanel uses a modified FlowLayout from SO user jxd in this question.
This may be information overkill but the full nesting of the panel in question is as follows:
JPanel (ModifiedFlowLayout) > JScrollPane > JPanel (GridBagLayout) > JTabbedPane > JPanel (GridBagLayout) > JSplitPane > JPanel (BorderLayout) > JFrame.
The problem is that when I call pack() on my JFrame the JScrollPane/JPanel expands horizontally to fill the entire remaining screen space (across multiple monitors). The space used is more than is needed to display all of the components in the JPanel. I tried using setMaximumSize() on my JPanel but it seems to be ignored in this scenario.
Ideally I would like the panel to have it's size dictated by space left after sizing the components that surround it. Can/how can this been done?
The preferred size of a FlowLayout will try to display all components on a single row. I don't know how the ModifiedFlowLayout works but you can check out Wrap Layout which does the same thing.
However, when using Wrap Layout you can use the setSize(...) method to make a suggestion as to what the initial width should be. Initial wrapping of components should then be based on that size.
I have a JTabbedPane with a Border Layout.
Here's the code I'm using to add the components:
add(columnNames, BorderLayout.NORTH);
add(scroll, BorderLayout.CENTER);
add(useCtrl, BorderLayout.SOUTH);
setVisible(true);
Question:
Notice the excess whitespace to the right inside the JScrollPane. I don't want that there. I would like for the JScrollPane not to change size at all when changing the size of the JFrame. I have tried setSize() and setPreferredSize(), but the size of the JScrollPane always changes. I've tried using GridLayout, but I get the same result.
Place the JScrollPane in a JPanel with another layout. (e.g. BoxLayout or GridBagLayout). And add the JPanel to the center.
The size of a graphics object is controlled by the layout manager. The BorderLayout will always expand the CENTER object to take up all available space. GridLayout expands all it's children proportionally. If you try a GridBagLayout and set the weightx to 0, that will prevent expansion horizontally.
There are a lot of layout managers available, browse the API for more choices and experiment until you find the resizing behavior you want. Each has a fairly good explanation of how it works in the javadoc.
I have been trying to use JScrollPane with my applet, but it doesn't work. I have a JPanel to which I add 20 buttons, and I want to be able to scroll up and down this JPanel. Instead, the scrollbars do not appear. When I use setPreferredSize they still did not appear even though only about 3 of the buttons are being displayed and the rest are cut off. If I do not use setPreferredSize, there might as well not be any scrollbars because I have to make the window big enough to see all of the buttons. If I try to make the scrollbars always visible, they appear but do nothing. I tried the exact same code with JFrame instead of Applet, and it works fine, but I need it to be an applet. Is JScrollPane incompatible with applets? (Note: I tried to use an outer JPanel and add the scrollable panel to it, but it changed nothing). Changing the layouts also doesn't fix the problem. I have attached a simplified version of my code, but it displays the same errors.
Here is the code I have:
JPanel scrollPanel = new JPanel();
scrollPanel.setLayout(new BoxLayout(scrollPanel, BoxLayout.PAGE_AXIS));
JScrollPane scroll = new JScrollPane(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
for (int i = 0; i < 20; i++) scrollPanel.add(new JButton("Button " + i));
add(scrollPanel);
validate();
You never all the panel to the scroll pane
You never add the scroll pane to the applet
The basic code should be:
JScrollPane scrollPane = new JScrollPane(...);
scrollPane.setViewportView( scrollPanel );
add( scrollPane );
You are adding components to a Panel so you shouldn't expect to see a scroll pane wihout showing the scrollpane. What you want to do is then add that panel to a scrollpane which would be added to ur main container.
From your code, i think your problem is
add(scrollPanel);
your should be doing this
add(scroll);`
This is because you only added the panel to the frame which does not contain any scrollpane. Since you have added the panel unto the scrollpane, you should add the scrollpane and not the panel to the main container.
It sounds like you are using Swing components (JScrollPane, JPanel, ...) in an AWT container (Applet). Try using JApplet instead.
I want to add a Jpanel on a jscrollpane; also I want to have only vertical scrolling. I want to set layout of my jPanel "flowLaout" and add several components to my jPanel in my code by jpanel.add(component) method. The result is that all components are placed in just one row that excide width of jpanel and are not shown. I have used this tricks and both failed:
jScrollPane1.setHorizontalScrollBar(null);
jScrollPane1.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
Wrap Layout should work for you.
I am unsure of the particulars for your current project, but i would recommend MigLayout. It has never served me wrong.
I am currently writing a touchscreen interface with nested MigLayout panels up to 4 or five layers deep, and have not had a single problem.
Please use the below policy to turn on vertical scrolling and turn off horizontal scrolling(Works with Java SE 7):
Panel graphicPanel = new Panel();
JScrollPane scrollbar = new JScrollPane(graphicPanel);
scrollbar.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
scrollbar.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
scrollbar.setPreferredSize(new Dimension(1300, 600));
scrollbar.setVisible(true);
add(scrollbar, BorderLayout.CENTER);