java simple JPanel management (see screenshot)

I have a JPanel that encapsulates two JPanels, one on top of the other.

The first holds two JLabels which hold the开发者_运维知识库 playing cards.

The second holds the player's text (name and score).

However, when I remove the player's cards, the lower JPanel moves up to the top, which i would prefer that it not do. Is there a way to keep it in place regardless of whether the top JPanel is occupied or not?

Thanks

What layout managers are you using? The default layout manager for a JPanel is a FlowLayout which render child components one after the other.

Maybe you could set the root JPanel to have a BorderLayout. Then set the top JPanel to the root panel's "top" spot:

JPanel rootPanel = ...;
JPanel topPanel = ...;
rootPanel.add(topPanel, BorderLayout.TOP);

Then set a minimum size for your top JPanel:

topPanel.setMinimumSize(new Dimension(someWidth, someHeight));

And add the second panel to the bottom or middle spot:

rootPanel.add(secondPanel, BorderLayout.CENTER);

Check out http://java.sun.com/docs/books/tutorial/uiswing/layout/border.html

I had time to do an example:

public class TestJpanel extends JFrame {


    public TestJpanel() {
        this.setLayout( new BorderLayout() );

        final JLabel card1 = new JLabel( "card1" );
        final JLabel card2 = new JLabel( "card2" );

        final JPanel topPanel = new JPanel();
        topPanel.setPreferredSize( new Dimension( 1024, 100 ) );
        topPanel.add( card1 );
        topPanel.add( card2 );

        this.add( topPanel, BorderLayout.NORTH );

        JPanel centerPanel = new JPanel();
        final JButton hideCardsButton = new JButton( "Hide cards" );
        hideCardsButton.addActionListener( new ActionListener() {

            @Override
            public void actionPerformed( ActionEvent e ) {
                if ( topPanel.getComponentCount() == 0 ) {
                    topPanel.add( card1 );
                    topPanel.add( card2 );
                    hideCardsButton.setText( "Hide cards" );
                } else {
                    topPanel.removeAll();
                    hideCardsButton.setText( "Show cards" );
                }
                topPanel.validate();
                topPanel.repaint();
            }
        } );
        centerPanel.add( hideCardsButton );

        this.add( centerPanel, BorderLayout.CENTER );
    }

    public static void main( String[] args ) {
        TestJpanel window = new TestJpanel();
        window.setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
        window.setSize( 1024, 768 );
        window.setVisible( true );
    }

}

Note that this code if full of bad practices but helps demonstrate what I want with a short number of lines.