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Understanding JTable.addColumn()

Stephan Mueller
Ranch Hand

Joined: May 05, 2010
Posts: 50
Hello folks,

this is a hacky approach at understanding swing's JTable, based on Sun's Demo Application. After clicking into the table, a new column is added and displayed (my custom datamodel registers as listener to the columnAdded-Event). I'm expecting to have cell-value for this new column = "argh" but the value is the same as it is for the first column (Mary). I don't get this. What am I missing here? The TableDemo.debugColumnAdd output at least assumes that argh is returned for the new column. So why/how are the renderers calling tableModel.getValueAt(...)? Instead of using columnIndex 5 they wrap back to 0.

The main class:


My custom tableModel:


1. Make it run - 2. Make it run correctly - 3. Make it pretty OR fast/small - 4. ??? - 5. Profit
Stephan Mueller
Ranch Hand

Joined: May 05, 2010
Posts: 50
Solution:
TableColumn foo = new TableColumn(); creates a new TableColumn with a model index of 0! That's why the code always returns Mary (getValueAt(0,0)) instead of the expected argh (getValueAt(0,5))
TableColumn foo = new TableColumn(5); is the solution for adding one column, otherwise TableColumn foo = new TableColumn(tableModel.getColumnCount); would be for adding arbitrary numbers of columns.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: Understanding JTable.addColumn()