GridBagLayout compnent's position not working

Question

Hi i am beginner to java and doing small GUI using GridBagLayout. See the attached code and also the output . what i want is to place the JButtons on top left corner as per the position assigned in gridx and gridy . But it placing components in center instead of top left as expected , if i use Insets , gridx /gridy all that is working but not from proper coordinates so please see attached code and image and guide me about it

public  rect()
{     

      JPanel panel = new JPanel( new GridBagLayout());
      GridBagConstraints gbc = new GridBagConstraints();
      JButton nb1= new JButton("Button1  ");
      JButton nb2= new JButton("Button2  ");

      gbc.gridx=0;
      gbc.gridy=0 ;
      panel.add(nb1, gbc);
      gbc.gridx=1;
      gbc.gridy=1; 
      panel.add(nb2, gbc);
      panel.setVisible(true);
      JFrame  frame = new JFrame("Address Book "); 
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
      frame.setSize(300, 300 );
      frame.add(panel);

      frame.setVisible(true); 


}

OUTPUT : want these buttons on top left please guide me

Answer 1

I think the problem is more the use of setSize(..), you should rather use appropriate LayoutManager and call pack() on JFrame instance after adding all components to JFrame and before setting JFrame visible, also no need for panel.setVisible(..):

public static void main(String[] args) {

    SwingUtilities.invokeLater(new Runnable() {
        @Override

        public void run() {
            JPanel panel = new JPanel(new GridBagLayout());

            JButton nb1 = new JButton("Button1  ");
            JButton nb2 = new JButton("Button2  ");

            GridBagConstraints gbc = new GridBagConstraints();

            gbc.gridx = 0;
            gbc.gridy = 0;
            panel.add(nb1, gbc);

            gbc.gridx = 1;
            gbc.gridy = 1;
            panel.add(nb2, gbc);

            JFrame frame = new JFrame("Address Book ");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            frame.add(panel);

            frame.pack();
            frame.setVisible(true);
        }
    });
}