Customized table renderer

Question

I have written my own table cell renderer based somewhat on jdk?s DefaultTableCellRenderer - taking into account all performance issues mentioned in the Note section of JDK doc for that class.
My renderer extends JPanel , contains a few JTextField components and the function getTableCellRendererComponent returns simply ?this? reference.
In my JTable derived class in function addItem() I am iterating through all my data in the model. For every data item I am calling renderer?s getTableCellRendererComponent to initialize renderer component and then I ask that component for its preferred size (calling getPreferredSize) saving the biggest width found so far.
Somehow the renderer component always returns to me the width that is correct for the very first data item from model.
Below is fragment of my code, any idea what is wrong with my code?
JD
* This method picks good column sizes.
* If all column heads are wider than the column's cells'
* contents, then you can just use column.sizeWidthToFit().
private void initColumnSizes()
MyTableModel model = (MyTableModel)actionTable.getModel();
TableColumn column = null;
Component comp = null;
int headerWidth = 0;
int cellWidth = 0;
int maxCellWidth = 0;
for(int j = 0; j < model.getRowCount(); j++)
for (int i = 0; i < model.getColumnCount(); i++)
column = actionTable.getColumnModel().getColumn(i);
comp = actionTable.getTableHeader().getDefaultRenderer().
getTableCellRendererComponent(null, column.getHeaderValue(),
false, false, 0, 0);
headerWidth = comp.getPreferredSize().width;
comp = actionTable.getDefaultRenderer(model.getColumnClass(i)).
getTableCellRendererComponent(actionTable, model.getValueAt(j, i),
false, false, 0, i);
cellWidth = comp.getPreferredSize().width;// !!!!
maxCellWidth = Math.max(maxCellWidth, Math.max(headerWidth, cellWidth));
column.setPreferredWidth(maxCellWidth);

Answer 1

The renderer components are just used for drawing purposes.
Therefor, you can not iterate through them to find the widest of them for your data, because in most cases, there will only be a single one for your whole table.
You need to iterate through the data of your model and use that as a basis for calculating the width of each column, not the cellrenderer.