Centering a jFrame

Question

I'm trying to locate my frames at the center of the screen , I know that this code must work well:

Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
int x = (int) ((screen.getWidth() - getWidth()) /2);
int y = (int) ((screen.getHeight() -getHeight()) /2);
setLocation(x, y); 

or this one :

Toolkit tk = Toolkit.getDefaultToolkit();
Dimension screenSize = tk.getScreenSize();
int screenHeight = screenSize.height;
int screenWidth = screenSize.width;
setSize(screenWidth / 2, screenHeight / 2);
setLocation(screenWidth / 4, screenHeight / 4);

I have tried all the possible codes but I don't know why they don't work, the just move the frame to the bottom right corner of the screen I have used setRelative to null but again it doesn't work.

I could finally bring the frame very close to the center by multiplying the width by 5 and dividing it by something but I know that this is not the right way.

could anyone please explain to me what could be wrong ?

Problem Fixed :

solution: I found the best way myself , if you ever come up with the same problem simply let the netbeans do that automatically by going to properties and checking generate center , forget about the stupid codes.

Answer 1

The easiest way to center frame on the main screen (there are options if you have multiply screens) is to use setLocationRelativeTo(...) frame method with null as argument:

JFrame frame = new JFrame ();
frame.setSize ( 500, 300 );
frame.setLocationRelativeTo ( null );
frame.setVisible ( true );

In case that doesn't work - try this one (direct coordinates):

Dimension ss = Toolkit.getDefaultToolkit ().getScreenSize ();
Dimension frameSize = new Dimension ( 500, 300 );

JFrame frame = new JFrame ();
frame.setBounds ( ss.width / 2 - frameSize.width / 2, 
                  ss.height / 2 - frameSize.height / 2,
                  frameSize.width, frameSize.height );
frame.setVisible ( true );

Last and "ultimate" example - it will display centered frame @ each available system screen:

public static void main ( String[] args )
{
    Dimension frameSize = new Dimension ( 500, 300 );
    for ( GraphicsDevice screen : getGraphicsDevices () )
    {
        GraphicsConfiguration gc = screen.getDefaultConfiguration ();
        Rectangle sb = gc.getBounds ();

        JFrame frame = new JFrame ( gc );
        frame.setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE );
        frame.setBounds ( sb.x + sb.width / 2 - frameSize.width / 2,
                sb.y + sb.height / 2 - frameSize.height / 2, frameSize.width,
                frameSize.height );
        frame.setVisible ( true );
    }
}

public static List<GraphicsDevice> getGraphicsDevices ()
{
    List<GraphicsDevice> devices = new ArrayList<GraphicsDevice> ();
    for ( GraphicsDevice gd : GraphicsEnvironment.getLocalGraphicsEnvironment ()
            .getScreenDevices () )
    {
        if ( gd.getType () == GraphicsDevice.TYPE_RASTER_SCREEN )
        {
            if ( gd == GraphicsEnvironment.getLocalGraphicsEnvironment ()
                    .getDefaultScreenDevice () )
            {
                devices.add ( 0, gd );
            }
            else
            {
                devices.add ( gd );
            }
        }
    }
    return devices;
}

Answer 2

It's enough if you use

setLocationRelativeTo(null);

According to Javadoc for java.awt.Window.setLocationRelativeTo(),

If the component is null, ... the window is placed in the center of the screen.