Given the following code:
(Not my actual code, just the simplest code I could knock together which repros the issue)

package com.example;

import javax.swing.Box;
import javax.swing.BoxLayout;
import java.awt.BorderLayout;
import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
 
public class JTableExample {
    JFrame f;
    JTable table;
 
    JTableExample()
    {
        f = new JFrame();
        f.setTitle("JTable Example");
        String[][] data = {
            { "Kundan Kumar Jha", "4031", "CSE" },
            { "Anand Jha", "6014", "IT" }
        };
 
        String[] columnNames = { "Name", "Roll Number", "Department" };
 
        JPanel outerPanel = new JPanel();
        outerPanel.setLayout(new BoxLayout(outerPanel, BoxLayout.Y_AXIS));

        for (int i = 0 ; i < 3; i++){
            JPanel tablePanel = new JPanel(new BorderLayout());
            table = new JTable(data, columnNames);
            tablePanel.add(table.getTableHeader(), BorderLayout.PAGE_START);
            tablePanel.add(table, BorderLayout.CENTER);
            outerPanel.add(tablePanel);
            outerPanel.add(Box.createRigidArea(new Dimension(0,20)));
        }
 
        JScrollPane sp = new JScrollPane(outerPanel);
        f.add(sp);
        f.setSize(500, 400);
        f.setVisible(true);
    }
 
    public static void main(String[] args)
    {
        new JTableExample();
    }
}

You get a window which looks like so:

What I want is for the tables to all be packed at the top of the window, with all the blank space at the bottom, like so:
(I bodged this screenshot by adding 20 JPanels after the tables)

I have attempted to use a GridBagLayout, but what ends up happening is this:
(Everything just floating in the middle of the window)

Can anyone help me understand what I am doing wrong?
In case it matters, in my actual code, there is an arbitrary number of tables, it’s not fixed.