codice:
 
import javax.swing.*;
import java.awt.*;

public class FrameExampleLayout extends JFrame {

   public FrameExampleLayout() {
      setLayout(new BorderLayout());
      ...
      ...
      ... 
      ...
      add(new PannelloGrid(), "Center");
      ....
      ....
      setVisible(true);
   }
}

public class PannelloGrid extends JPanel {

   public PannelloGrid() {
      setLayout(new GridLayout());
      ...
      ...
      ...
      ...
      add(quello_che_vuoi_tu, JButton_JTextField_altri pannelli_etc....);
      ....
      ....
   }
}