Now that I managed to put the objects from a file into a ArrayList, I have to display them into a JTable.
These are the 3 objects contained in
Use your TableModel to create a JTable and add it to a JFrame. Also consider overriding getColumnName(), as shown here. See also How to Use Tables.
MonModel model = new MonModel();
JTable table = new JTable(model);
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new JScrollPane(table), BorderLayout.CENTER);
f.pack();
f.setLocationByPlatform(true);
f.setVisible(true);