JPanel size by inner components

Answer 1

maybe you can do something like that by removing from your panel

setResizable(false);

Answer 2

After looking at the source code for pack(), I came up with:

    panel.setPreferredSize(panel.getPreferredSize());

This forces the panel to recalculate its preferred size based on the preferred sizes of its subcomponenents.

You may or may not have to call validate() afterward; in my tiny example, it seemed to make no difference, but the Javadoc says:

The validate method is used to cause a container to lay out its subcomponents again. It should be invoked when this container's subcomponents are modified (added to or removed from the container, or layout-related information changed) after the container has been displayed.

So I guess it depends on why you're having to repack your JPanel.

Answer 3

By default Containers have a preferred size that matches the preferred layout size given by the container. So literally all you have to do is:

panel.setSize(panel.getPreferredSize());

Presumably you are doing something odd with the parent to stop the parent's layout manager doing the equivalent of this.

Answer 4

I would try:

panel.revalidate();
panel.repaint();

This will not necessarily set the panel to its preferred size, that is more dependent on what the layout manager decides to use.

This is useful in cases where you have added/removed components from a panel that is currently displayed and visible.

Update: Based on your screenshot I can say the following: 1) Consider programatically changing the divider location. 2) Consider programatically resizing the window itself horizontally since it seems to be a little tight to show both sides of the split pane. Or both. You can set the divider location by doing

splitPane.setDividerLocation(newSize);

Keep in mind that there are two overloaded methods for this, one taking a float one taking an int. The float does a percentage of the size while the int is the size in pixels. The size is for the left hand panel (or top panel for that orientation). I would consider possibly changing the divider location based on the preferred width of the panels.

Answer 5

JSplitPanes are a bit fussy when it comes to its children's sizes, have a look at the Java tutorial. Are you using the GridBagLayout correctly? Looks like it's not setting the right JPanel's minimum size properly.