JTable not showing table header

Question

My goal is to display data from a database using JTable.

Referencing code from: Most simple code to populate JTable from ResultSet

I modified the code to suit my situation. I have a class TopicData with the following method:

public DefaultTableModel buildTableModel(){
    //open connection
    ResultSet rs = null;
    Vector<String> columnNames = new Vector<String>();
    Vector<Vector<Object>> data = new Vector<Vector<Object>>();
    int columnCount = 0;
    DBController db = new DBController();
    db.setUp("myDatabase");
    String dbQuery = "SELECT topicName, topicDate, topicCategory, topicUser FROM topicTable ORDER BY topicDate";

    rs = db.readRequest(dbQuery);
    try{    
        ResultSetMetaData metaData = rs.getMetaData();

        // names of columns
        columnCount = metaData.getColumnCount();
        for (int column = 1; column <= columnCount; column++) {
            columnNames.add(metaData.getColumnName(column));

        }
        // data of the table 
        while (rs.next()) {
            Vector<Object> vector = new Vector<Object>();
            for (int columnIndex = 1; columnIndex <= columnCount; columnIndex++) {
                vector.add(rs.getObject(columnIndex));
            }
            data.add(vector);
        }
    } 
    catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    //close connection 
    db.terminate();

    return new DefaultTableModel(data, columnNames);

}

And in another class TopicView:

private JTable getTable() {
    if (table == null) {
        TopicData topic= new TopicData();
        table = new JTable(topic.buildTableModel());
        table.setShowGrid(false);
        table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        table.setBounds(95, 59, 625, 357);
    }
    return table;
}

I realized that my table does not have headers at the top of each column. https://i.stack.imgur.com/FcnHb.png

So I simplified my TopicData to troubleshoot:

public DefaultTableModel testTableModel(){
    Vector<String> columnNames = new Vector<String>();
    columnNames.add("test1");
    columnNames.add("test1");
    columnNames.add("test1");
    Vector<Vector<Object>> data = new Vector<Vector<Object>>();
    Vector<Object>vector = new Vector<Object>();
    vector.add("test2");
    vector.add("test2");
    vector.add("test2");
    data.add(vector);

    return new DefaultTableModel(data, columnNames);
}

Once again, the table does not have headers. The word "test1" does not appear anywhere on the table, while there are 3 columns of "test2" displayed.

I'm really puzzled by this, any help would be appreciated.

mKorbel · Accepted Answer · 2013-01-10T14:07:17.570

put JTable to the JScrollPane,
otherwise have to change LayoutManager to the BorderLayout for container, then to put JTable to the CENTER area, and getTableHeader from JTable and put JTableHeader to the NORTH / SOUTH
proper way is by using JScrollPane

EDIT

how do I make the fields in the table uneditable? Right now if I double click I can edit the content of the cells

override both methods for DefaultTableModel, pseudo_code

model = new DefaultTableModel(data, columnNames) {

    private static final long serialVersionUID = 1L;

    @Override
    public Class getColumnClass(int column) {
        return getValueAt(0, column).getClass();
    }

    @Override
    public boolean isCellEditable(int row, int column) {
        return false;
    }
};
table = new JTable(model);

I see! lol I spent the whole day reading on vectors and table models and it turns out I'm doing it wrong. On another note, how do I make the fields in the table uneditable? Right now if I double click I can edit the content of the cells. — AmuletxHeart, Jan 10 '13 at 14:00

score 1 · Answer 2 · answered Jan 10 '13 at 14:09

Put your table in the JScrollPane.

Example:

container.add(new JScrollPane(table));

or you can do it by directly adding to the container (as stated in the javadoc)

container.setLayout(new BorderLayout());
container.add(table.getTableHeader(), BorderLayout.PAGE_START);
container.add(table, BorderLayout.CENTER);

For your question on how to make a cell not editable is,

Override isCellEditable(..) in your TableModel

@Override
public boolean isCellEditable(int rowIndex, int colIndex) {
    // return false for not making it editable.
     return false; 

}

JTable not showing table header

2 Answers2