根据内容大小设置框架最小尺寸

Question

I can find plenty of questions tackling the issue of how to get the "real" size of a JFrame not counting its border, but this is different: I have a JFrame with some contents, and I want to set the JFrame's minimum size so that its content pane can't be smaller than the size of those contents. Simply doing something like

setMinimumSize(getContentPane().getPreferredSize())

doesn't work, of course, because the frame's size incorporates its border, any menu bar, etc. -- so you'd still be able to shrink the frame down small enough that part of the contents get clipped. So I came up with this solution instead:

  // Set minimum size so we can't resize smaller and hide some of our
  // contents. Our insets are only available after the first call to
  // pack(), and the second call is needed in case we're too small.
  pack();
  Dimension contentSize = getContentPane().getPreferredSize();
  Insets insets = getInsets();
  Dimension minSize = new Dimension(
        contentSize.width + insets.left + insets.right,
        contentSize.height + insets.top + insets.bottom + 
        (getJMenuBar() != null ? getJMenuBar().getSize().height : 0));
  setMinimumSize(minSize);
  pack();

This appears to work, but it feels very hacky, in particular with the assumption that the only possible space dedicated for decorations will be taken into account via the insets and a potential menubar (which only affects the height). Surely there's a better solution, right?

If not, well, hopefully the next time someone has this problem, they'll be able to find my workaround solution. :)

Answer 1

The minimum size you want is just the size of the frame AFTER you do the initial pack();

frame.pack();
frame.setMinimumSize( frame.getSize() );