JTable won't show column headers

Put your JTable inside a JScrollPane. Try this:

add(new JScrollPane(scrTbl));

The main difference between this answer and the accepted answer is the use of setViewportView() instead of add().

How to put JTable in JScrollPane using Eclipse IDE:

1. Create JScrollPane container via Design tab.
2. Stretch JScrollPane to desired size (applies to Absolute Layout).
3. Drag and drop JTable component on top of JScrollPane (Viewport area).

In Structure > Components, table should be a child of scrollPane.

The generated code would be something like this:

JScrollPane scrollPane = new JScrollPane();
...

JTable table = new JTable();
scrollPane.setViewportView(table);

As said in previous answers the 'normal' way is to add it to a JScrollPane, but sometimes you don't want it to scroll (don't ask me when:)). Then you can add the TableHeader yourself. Like this:

JPanel tablePanel = new JPanel(new BorderLayout());
JTable table = new JTable();
tablePanel.add(table, BorderLayout.CENTER);
tablePanel.add(table.getTableHeader(), BorderLayout.NORTH);