GridBagLayout水平堆叠按钮而不是垂直堆叠按钮，而不是递增的Gridy值

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class GridBagLayoutExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("GridBagLayout Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        panel.setLayout(new GridBagLayout());

        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.HORIZONTAL;
        constraints.insets.top = 5;
        constraints.insets.left = 5;
        constraints.insets.right = 5;

        JButton button1 = new JButton("Button 1");
        constraints.gridx = 0;
        constraints.gridy = 0;
        constraints.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(button1, constraints);

        JButton button2 = new JButton("Button 2");
        constraints.gridx = 0;
        constraints.gridy = 1;
        constraints.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(button2, constraints);

        JButton button3 = new JButton("Button 3");
        constraints.gridx = 0;
        constraints.gridy = 2;
        constraints.gridwidth = GridBagConstraints.REMAINDER;
        panel.add(button3, constraints);

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