Setting size of JPanel using MiGLayout

Question

I'm using the MiGLayout to create several different JPanels, however I'm having a problem resizing one of them. Below is a diagram showing what I want to achieve:

-------------------------------------------------------
|                                                     |
|                        Panel 1                      |
|                                                     |
-------------------------------------------------------
--------------------------- ---------------------------
|                         | |                         |
|         Panel 2         | |          Panel 3        |
|                         | |                         |
--------------------------- ---------------------------

The key thing I want to achieve is to make Panel 1 spread across the two other panels. I seem to have achieved this layout, however I've got an issue such that the border isn't showing up for Panel 1 as shown in my diagram. I have tried using the setSize method but it didn't seem to work.

Here is the code I'm using to create the panels (please note I haven't included the widgets inside the panel):

    // Create Panel 1
    JPanel panelOne = new JPanel();
    panelone.setSize(600, 50);
    panelOne.setBorder(BorderFactory.createTitledBorder("Panel 1"));
    panelOne.setLayout(new MigLayout());

    // Create Panel 2
    JPanel panelTwo = new JPanel();
    panelTwo.setBorder(BorderFactory.createTitledBorder("Panel 2"));
    panelTwo.setLayout(new MigLayout());

    // Create Panel 3
    JPanel panelThree = new JPanel();
    panelThree.setBorder(BorderFactory.createTitledBorder("Panel 3"));
    panelThree.setLayout(new MigLayout());

    // Add the panels to the main frame
    mainFrame.add(panelOne, "span, wrap, align center");
    mainFrame.add.add(panelTwo);
    mainFrame.add.add(panelThree);

Please can someone suggest a way to get the border to be shown as in my diagram?

Answer 1

Try this:

mainFrame.getContentPane().setLayout(new MigLayout());
getContentPane().add(panelTwo);
getContentPane().add(panelThree,  "wrap");   // Wrap to next row
getContentPane().add(panelOne, "dock north");

Also, ensure you are adding your GUI elements to the main frame's content pane not to the frame itself.

EDIT From the comments below: You can also use new CC.wrap() or new CC.dockNorth() Thanks to @Andrew Thompson and @Howard for the tip :)

Answer 2

panelone.setSize(600, 50);  // from original code

I've never used that layout, but layouts in general are more likely to respect (enforce) the preferred size than the size.