Java GridLayout .preferredLayoutSize (Container parent)

public Dimension preferredLayoutSize(Container parent)

//from  w w w. j  a  va  2s .c om
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JPanel {

  public Main(){
    
    add(new JButton("w w w.j a v a 2 s . c o m"));
    add(new JButton("w w w.j a v a 2 s . com" ));
    add(new JButton("w w w.java2s.com" ));
    add(new JButton("www.j ava 2 s . c o m" ));
    
    GridLayout gridLayout = new GridLayout();
    
    setLayout(gridLayout);
    
    System.out.println(gridLayout.preferredLayoutSize(this));
  }
  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.getContentPane().add(new Main());

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200,200);
    frame.setVisible(true);
  }
}