JTable inside JScrollPane: best height to disable scrollbars

Question

I am using the following code to create JTable inside JScrollPane to show column headers

JTable won't show column headers

Answer 1

The basic approach is

• JTable is-a Scrollable which unfortunately doesn't do too well in calculating a prefScrollable, so you have to do it yourself
• either use a LayoutManager which lays out all at their pref (f.i. FlowLayout), or implement max in JTable (if you use a resizing but max-respecting manager like BoxLayout)
• JScrollPane is-a validationRoot, so the revalidate must happen on the parent of the scrollPane

Something like:

final JTable table = new JTable(10, 5) {

    @Override
    public Dimension getPreferredScrollableViewportSize() {
        Dimension dim = super.getPreferredScrollableViewportSize();
        // here we return the pref height
        dim.height = getPreferredSize().height;
        return dim;
    }

};
final JComponent content = new JPanel();
content.add(new JScrollPane(table));
Action add = new AbstractAction("add row") {

    @Override
    public void actionPerformed(ActionEvent e) {
        ((DefaultTableModel) table.getModel()).addRow(new Object[]{});
        content.revalidate();
    }
};