swing question on resize controls on maximize

I have a JFrame with the following layout and components:

 _________________________________________ 
 |  __________________________________    | 
 |  |JTree   |   Panel2              | *  |
 |  |(Panel1)| (other controls)      |<-> |
 |  |________|_______________________|    |
 |__________*_____________________________|

These are in the contentpane of the main JFrame.

What I want is when I maximize the window, these components to resize accordingly.

What happens now is that they remain in their current size and there is a huge gap at the place I have the arrow and stars.(Side and bottom).

I would like to remain packed.

I have used null layout for content pane and dropped the components from a visual designer.

How can I make the controls alway开发者_运维百科s resize on mazimize?

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If you want the two panels to have equal size, each occupying half of the main window, use GridLayout:

getContentPane().setLayout(new GridLayout(1,2));
getContentPane().add(Panel1);
getContentPane().add(Panel2);

If you want one panel to have constant width, use BorderLayout:

getContentPane().setLayout(new BorderLayout());
getContentPane().add(Panel1,BorderLayout.EAST);
getContentPane().add(Panel2,BorderLayout.CENTER);

If you want more complex behaviour, e.g. to maintain the 1:2 width ratio, you will have to use GridBagLayout which is the most powerful layout but also the most complicated:

getContentPane().setLayout(new GridBagLayout());
getContentPane().add(Panel1,new GridBagConstaints(0,0,1,1,1,1,GridBagConstraints.CENTER,GridBagLayout.BOTH,new Insets(0,0,0,0),0,0);
getContentPane().add(Panel2,new GridBagConstaints(1,0,1,1,2,1,GridBagConstraints.CENTER,GridBagLayout.BOTH,new Insets(0,0,0,0),0,0);

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Don't use null layout, don't use a form designer, but rather experiment with the various layout managers. GridBagLayout may be one of the managers that could help you create a GUI as desired, but many try to avoid using this one unless necessary. Many also nest JPanels each with its own layout manager so in effect nesting the layout managers.

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If you search SO you'll probably get many different opinions. There is one common truth though: you need to have at least a basic understanding of how a certain layout manager works before even thinking of using a visual designer.

Having said that, the best results I got, and what I currently use in production is a combination of the great WindowBuilderPro and MigLayout as a layout manager.

I actually use MigLayout as a table layout. I put my components in cells and I set each cell with attributes like "grow" - if I want to expand on resize, minimum/pref/max size, alignment, etc. I can set components to span across cells and I get exactly what I want.

The great thing about WindowBuilder is that you can change the generated code without messing the designer, and the generated code it's actually pretty :)