Java Swing - 如何对于两个元素使用GridBagConstraint.anchor = NORTH

import java.awt.Color;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Main extends JFrame {

  public Main() {
    this.setDefaultCloseOperation(EXIT_ON_CLOSE);

    this.setLayout(new GridBagLayout());
    GridBagConstraints gbc = new GridBagConstraints();

    gbc.anchor = GridBagConstraints.NORTH;
    gbc.weighty = 0.0;

    JPanel one = new JPanel();
    one.setPreferredSize(new Dimension(200, 200));
    one.setBorder(BorderFactory.createLineBorder(Color.BLACK));

    JPanel two = new JPanel();
    two.setPreferredSize(new Dimension(200, 200));
    two.setBorder(BorderFactory.createLineBorder(Color.BLACK));

    this.add(one, gbc);

    gbc.gridy = 1;
    gbc.weighty = 0.0;
    gbc.fill = GridBagConstraints.VERTICAL;

    this.add(two, gbc);

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

  public static void main(String[] args) {
    new Main();
  }
}