How to Set JPanel's Width and Height?

Question

I'm developing Snake game using Java. Board's (where all action takes it place) width and height should be fixed (640 pixels * 480 pixels).

Structure:

• Main class that extends from JFrame class,
• Board class that extends from JPanel class;

In Main class I have something like...

setSize( 1024, 768 );

...and in Board class I have...

setSize( BOARDS_WIDTH, BOARDS_HEIGHT );

Problem is that main and only windows seems to be like 1024 * 768, but panel inside it - not like 640 * 480. I have setBackground() as well and background is filled more than 640 * 480.

Is there any way to make Board's width and height like 640 * 480, but main windows width and height - as much as Board's width and height are correct?

Right now it looks like this...

Edit:

All works... almost.

Main class:

add( new Board(), BorderLayout.CENTER );
pack();
setResizable( false );
setLocationRelativeTo( null );
setVisible( true );
setDefaultCloseOperation( EXIT_ON_CLOSE );
setTitle( "Snake (by daGrevis)" );

Board class:

setPreferredSize( new Dimension( 640, 480 ) );

Gray background is 642 * 482! Like there would be border that wraps all by 1 pixel!

Answer 1

Board.setPreferredSize(new Dimension(x, y));
.
.
//Main.add(Board, BorderLayout.CENTER);
Main.add(Board, BorderLayout.CENTER);
Main.setLocations(x, y);
Main.pack();
Main.setVisible(true);