When I provide this code to mouseClicked method in MouseListener interface,
the changeableContentPanel is expanded. Could anyone help me?
if (!changeableContentPanel.isAncestorOf(aMO)) {
aMO = new AccountsManagementOptions();
changeableContentPanel.removeAll();
changeableContentPanel.validate();
changeableContentPanel.repaint();
aMO.setLocation(5, 100);
changeableContentPanel.add(aMO);
changeableContentPanel.validate();
changeableContentPanel.repaint();
}
When you remove/add components to the panel you should be using:
panel.remove(...);
panel.add(...);
panel.revalidate();
panel.repaint();
That is you should be using revalidate() instead of validate() and you only need to invoke the code once after all changes to the panel have been made.
the changeableContentPanel is expanded.
Yes, because the layout manager is invoked and the size of the panel will recalculated based on the size of the component added to the panel.
Could anyone help me?
If you don't want the size to change then you should be using a CardLayout on your panel. The panel size will be fixed to the size of the largest card added to the panel. Then you just swap components.
Read the section from the Swing tutorial on How to Use CardLayout for more information and working examples.
Related
I have a custom class that extends JPanel called Node that I want to be able to add to panel MainPanel through code, but the Nodes are not appearing. It works fine with drag and drop, but I want to add more Nodes during runtime.
but I want to add more Nodes during runtime.
When adding components to a visible GUI the basic code is:
panel.add(...);
panel.revalidate();
panel.repaint();
You need to invoke the layout manager to the component has a size and location otherwise the size is (0, 0) and there is nothing to paint.
I have a JFrame that has a JPanel inside. I call "setPreferredSize(new Dimension(500, 600));" but I want the JPanel and its contents to resize when someone resizes the JFrame.
BorderLayout is the way to go. Components start at their preferred size, but are expanded as needed to fill the region they are in.
Set your layout on your frame with BorderLayout
Add your JPanel by
frame.add(yourPanel, BorderLayout.CENTER);
This will allow it to stretch vertically & horizontally
As for the Contents inside a JPanel, give it a layout that will accommodate stretching as well.
Use a layout manager instead of setting the bounds for each component.
It is going to vary from program to program how you want your components to move.
Take a look at this and try to see which layout will work best for you.
So basically, I am trying to get a JPanel window which will display all components inside dynamically. In other words, which will re-size the window, and display to fit its content.
I have been able to do it with help of JFrame and its pack() method which : "causes this Window to be sized to fit the preferred size and layouts of its subcomponents".
In my situation, I dont want to use JFrame because it will require much effort to make all changes.
Right now, I am able to make it work but only with the help of jscroll inside which wraps the text and or any new lines, so the window size is more static. So my JPanel is extending a TopComponent and am able to display it with:
jpanel.open();
jpanel.requestActive();
So the question is how to resize a window to fit its content upon actions in that window.
The JPanel has to be added to a Window in order to make sense. So I suggest you use layout managers correctly and you will get to a decent user interface.
When you add/remove components from a visible panel you need to use:
panel.revalidate();
panel.repaint();
Then the layout manager will lay out the components again.
I am trying to create a JScrollPane that contains a JPanel that will be increasing and decreasing in height. When it becomes larger than the size of the JScrollPane, it should create a vertical scroll bar which will allow me to scroll through the entire JPanel. However, I am having difficulty achieving this. Yes, I know I am not using LayoutManagers. No, I will not be using them, and I need a solution that does not involve their usage.
Here are the two button's AbstractActions that add and subtract from the JPanel:
class AddACT extends AbstractAction
{
public void actionPerformed(ActionEvent e)
{
info.setSize(420,info.getHeight() + 40);
info.add(new SubPanel); // Adds another JPanel into the main JPanel (for content input)
gui.repaint();
infoS.validate();
}
}
class RemoveACT extends AbstractAction
{
public void actionPerformed(ActionEvent e)
{
info.remove(subPanel()); // This would remove the last JPanel added to the main JPanel
info.setSize(420,info.getHeight() - 40);
gui.repaint();
infoS.validate();
}
And here is the code for the main JPanel and the JScrollPane:
final JPanel info = new JPanel();
final JScrollPane infoS = new JScrollPane(info, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
info.setLayout(null);
info.setSize(420,600);
infoS.setLocation(10,80);
infoS.setSize(420,490);
gui.add(infoS); // gui is the frame's content pane (the overall JPanel)
This is the second project I've been trying to learn GUI by doing. I am a complete novice in Swing and am only intermediate in Java. Sorry if I am making a blindingly obvious mistake.
1) Use LayoutManagers (+1 to #kleopatra and #GagandeepBali comments)
The absence of LayoutManagers only guarantees your GUI's will look very trashy (especially when run on other OSes/builds) and being a Novice you should rather learn the correct way than learn the wrong way and get into bad habits like calling setSize() etc.
Have a read on these links to get you started:
A Visual Guide to Layout Managers
Concurrency in Swing
2) See this example for how to use a JScrollPane, it simply adds a JPanel with buttons to a JScrollPane which in-turn is added to the JFrame.
3) Also see this example for how to make the JScrollPane vertically scroll-able only.
4) For more on JScrollPanes have a look here: How to Use Scroll Panes.
5) As for how it interacts with LayoutManager, if you do not explicitly set its size via setPreferredSize(Dimension d) the scroll pane computes it based on the preferred size of its nine components (the viewport, and, if present, the two scroll bars, the row and column headers, and the four corners)
6) On your usage of validate():
validate() is used when new JComponents are added to a visible component
revalidate() is used when JComponent is removed/added from a visible component
revalidate() covers validate() too
Thus always use this:
//add or remove component(s)
revalidate();
repaint();
References:
http://www.daniweb.com/software-development/java/threads/405568/validate-vs-revalidate
LayoutManager is not required to solve the problem. The problem in Thrfoot's example is in these lines:
final JScrollPane infoS = new JScrollPane(info, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
info.setLayout(null);
info.setSize(420,600);
The program appears to recognize there is a need for scroll bars (it would show the scroll bar if your setting was VERTICAL_SCROLLBAR_AS_NEEDED), but the actual scrolling does not work (the scroll bar slider is not there).
To fix this, first set the preferred size of info, then construct the infoS.
Example:
info.setPreferredSize(420,600);
final JScrollPane infoS = new JScrollPane(info, ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
The idea is to set the preferred size of the info panel before it is used for the scroll pane. This is the same reason to set the size and location of infoS before adding to the gui:
infoS.setLocation(10,80);
infoS.setSize(420,490);
gui.add(infoS); // gui is the frame's content pane (the overall JPanel)
Suppose now there are some components inside a JPanel and the layout is arranged using GridBagLayout. Is it possible to change the weight(weightx or weighty) of the components dynamically (e.g. after pressing a button)? Thank you.
Remove and add the component with a new GridBagConstraint. After that call
panel.revalidate();
panel.repaint();
Use the method to get current constraints public GridBagConstraints getConstraints(Component comp)