setting a prototype value (for auto-width calculation) of a JTable column

Question

either this doesn't exist, or I'm not thinking/searching correctly because it's late...

I want to set a JTable column width in Swing based on a prototype value for the largest string I expect (or know) to exist in a particular column. I don't know the # of pixels since I don't necessarily know the font at compile time.

Is there a way to set a prototype value for column width purposes, the way there is for row height purposes? If so, how?

Answer 1

If you don't know the font at compile time then the width of any JTable column is always going to be unknown. As a sanity check, open a text document and play with different fonts whilst keeping the point size constant. The length of what is written varies on a font-by-font basis but the height doesn't.

The height of a JTable row should be able to be determined for any font size (in points) as it is a defined standard. It might take a bit of experimenting, though, given that JTable probably gives a bit of spacing inbetween cells.

If you can't guarantee neither the font size nor the font itself at compile time then I'm interested in what answers other people come up with :)

Answer 2

Have you tried creating a JLabel at run time and using its size to resize your table?

// create a label that will be using the run-time font
JLabel prototypeLabel = new JLabel("Not Applicable")

// get the labels preferred sizes
int preferredWidth = prototypeLabel.getPreferredSize().getWidth();
int preferredHeight = prototypeLabel.getPreferredSize().getHeight();

// set the sizes of the table's row and columns
myTable.setRowHeight(preferredHeight);

for(TableColumn column : myTable.getColumnModel.getColumns()){
   column.setPreferredWidth(preferredWidth);        
}

Answer 3

Instead of creating a Label, get the actual component from the TableCellRenderer and test the size on that:

// create the component that will be used to render the cell
Comp prototype = table.getDefaultRenderer(model.getColumnClass(i)).getTableCellRendererComponent(table, "Not Applicable", false, false, 0, i);

// get the labels preferred sizes
int preferredWidth = comp.getPreferredSize().getWidth();
int preferredHeight = comp.getPreferredSize().getHeight();

This is a single column example, you'll need to repeat this to get the size for each column (and also set it). See http://www.exampledepot.com/egs/javax.swing.table/PackCol.html for an example of this.