AddColumn() make removed column visible again. Pls help. :)

Question

I have a JTable which I need to remove and add column.
// declaration of table and tablemodel
DefaultTableModel tableMod = new DefaultTableModel (data, col);
// data is Object[][] type, col is String[] type
myTable = new JTable(defaultTableModel );
DefaultTableColumnModel columnMod = (DefaultTableColumnModel)myTable.getColumnModel();
My remove column code is :
columnMod.removeColumn(columnMod.getColumn(1));
My add column code is :
tableMod.addColumn("three");
My problem is : say my table has 2 columns initially
"one" "two"
after removeColumn(), the column will disappear from the JTable. like this
"one"
but when I addColumn() later, the removed column will appear again. like this
"one" "two" "three"
I think the problem is DefaultTableColumnModel is used to removeColumn but DefaultTableModel is used to addColumn, resulted in some kind of discrepancy, how to go about this? I know I can do perform addColumn() and removeColumn() on JTable, something like :
remove -
myTable.removeColumn(myTable.getColumnModel().getColumn( myTable.getSelectedColumn() ) );
add -
addedColumn = new TableColumn()
myTable.addColumn(addedColumn);
But when I do this addedColumn has a modelIndex of 0 , and anychanges to addedColumn will be reflected on first column(because modelIndex is 0) as well...which is what I don't want.
Hope I'm making sense, any help appreciated.

Answer 1

Ok, so heres my gripe with actually removing a column from a JTable : A JTable rebuilds its entire column model when it gets certain events (e.g. if the table model calls fireTableStructureChanged). This makes it unreliable to remove columns from the table by the method you give (though im not saying it cant be done, feel free to pursue that avenue if you like). Im just saying a more reliable way to do it is to have you own table model that knows exactly what the columns are to be in the JTable at any time. This way if the JTable rebuilds it column model it wont remake a column you removed.
So heres the basics of removing and adding a column by changing the table model :
A table model (derived from AbstractTableModel) needs to have three functions:
public int getRowCount();
public int getColumnCount();
public Object getValueAt(int row, int column);So if you're at a time when you only want one column, getColumnCount() should return 1. If you want to say add two columns, then have getColumnCount() return 3. You would then also need to change what gets returned by getValueAt() so that it tells what is in the three columns appropriately. Also, whenever the number of columns is changed, you would need to fireTableStructureChanged(), to let the table know to rebuild it column model, with or without the columns you want added/removed.
That is exactly what is done in the other post. I don't mean to not directly answer your question, i just don't think that removing and adding columns like that is how JTable is meant to be used, in MVC architechure. I dont really have any information about adding and removing columns because I've never even attempted to change a table that way. All i can say to that is that you have to figure out how JTable works, which I would try putting tons of System.out() calls telling me exactly what the column model looks like after certain changes(it indexes, etc..).
Well i hope this helps in some small way...
Josh