将GridLayout行移到顶部

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

public class GridLayoutExample extends JFrame {
    public GridLayoutExample() {
        setTitle("GridLayout Example");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        
        // 创建一个具有4行3列的GridLayout布局
        setLayout(new GridLayout(4, 3));
        
        // 创建并添加组件
        for (int i = 1; i <= 12; i++) {
            JButton button = new JButton("Button " + i);
            add(button);
        }
        
        // 将第3行的组件移到顶部
        setComponentAlignment(this, 2, Component.TOP_ALIGNMENT);
        
        pack();
        setVisible(true);
    }
    
    // 设置组件的对齐方式
    private void setComponentAlignment(Container container, int row, float alignment) {
        Component[] components = container.getComponents();
        
        for (int i = 0; i < components.length; i++) {
            if (i / 3 == row) {
                GridBagConstraints constraints = ((GridBagLayout) container.getLayout()).getConstraints(components[i]);
                constraints.anchor = GridBagConstraints.NORTH;
                constraints.insets = new Insets(5, 5, 5, 5);
                ((GridBagLayout) container.getLayout()).setConstraints(components[i], constraints);
                components[i].setAlignmentY(alignment);
            }
        }
    }
    
    public static void main(String[] args) {
        new GridLayoutExample();
    }
}