Using ListSelectionListener

[Dennis Putnam]

I am trying to write a selection listener and am not understanding something. I have a JTable with a selection model set to single selection. My objective is to add the selected row to an ArrayList but at this point I am just printing out values to understand what I am getting. Here is my listener:

table.getSelectionModel().addListSelectionListener(new ListSelectionListener() {

	@Override
	public void valueChanged(ListSelectionEvent e) {
		if (e.getValueIsAdjusting()) {
			int row=e.getFirstIndex();
			JTable table=ListActors.getTable();
			System.out.println(table.getValueAt(row, 0)+" "+table.getValueAt(row, 1)+" "+table.getValueAt(row, 2)+" "+table.getValueAt(row, 3)+" "+table.getValueAt(row, 4));
		}
	}
});

The first problem is that it seems to get invoked twice for each selection. That is, one click results in 2 identical lines of output. After clicking one row, then clicking another I get the original selection listed once plus the new one listed twice. Can someone explain when the listener is invoked and if it is invoked multiple times per click how I can identify the first invocation and ignore the rest? TIA.

[Darryl Burke]

Print the values returned by e.getFirstIndex(), e.getLastIndex() and e.getValueIsAdjusting() and you'll gain a better understanding of the selection change notification process.

[Dennis Putnam]

Thanks for the reply. Two things happened when I did that. The first is that the double invocation per click stopped (gremlins?). The second showed I really have a different problem. Apparently setting mode to SINGLE_SELECTION is not working or I am not understanding what it does. How do I set the mode so I get one index per click (i.e firstIndex=lastIndex every time not just the first time), if not with SINGLE_SELECTION?

[Ranganathan Kaliyur Mannar]

You did not print the e.getValueIsAdjusting() as suggested. Print it outside of the if and you will get an idea.

[Dennis Putnam]

I did but I don't see how that changes my question, I still cannot get SINGLE_SELECTION to work as expected.

[Darryl Burke]

Post an SSCCE and report what / where you clicked and what was printed to the console and we'll take it from there.

I still cannot get SINGLE_SELECTION to work as expected.

Then getExpectationIsAdjusting() should return true.

[Dennis Putnam]

What is getExpectationIsAdjusting()?

[Paul Clapham]

Darryl missed the I think. If your code isn't doing what you expected, then you have to adjust your expectation before you can fix the code.

[Dennis Putnam]

Duh! I missed that.

[Dennis Putnam]

On my way to looking up other things I finally figured this out. I mean a solution not necessarily the answer to my question. All I needed to do was clear the selection in the listener, then each invocation of the listener has a single selection.
[CODE=Java]
table.getSelectionModel().addListSelectionListener(new ListSelectionListener() {

@Override
public void valueChanged(ListSelectionEvent e) {
if (e.getValueIsAdjusting()) {
int row=e.getFirstIndex();
JTable table=ListActors.getTable();
System.out.println(table.getValueAt(row, 0)+" "+table.getValueAt(row, 1)+" "+table.getValueAt(row, 2)+" "+table.getValueAt(row, 3)+" "+table.getValueAt(row, 4));
table.getSelectionModel().clearSelection();
}
}
});

[Dennis Putnam]

On my way to looking up other things I finally figured this out. I mean a solution not necessarily the answer to my question. All I needed to do was clear the selection in the listener, then each invocation of the listener has a single selection.

    table.getSelectionModel().addListSelectionListener(new ListSelectionListener() {  
      
        @Override  
        public void valueChanged(ListSelectionEvent e) {  
            if (e.getValueIsAdjusting()) {  
                int row=e.getFirstIndex();  
                JTable table=ListActors.getTable();  
                System.out.println(table.getValueAt(row, 0)+" "+table.getValueAt(row, 1)+" "+table.getValueAt(row, 2)+" "+table.getValueAt(row, 3)+" "+table.getValueAt(row, 4));
                table.getSelectionModel().clearSelection();
            }  
        }  
    });

[Ranganathan Kaliyur Mannar]

Hi,
I don't think that is the right solution. You are trying to clear the selection inside a selection listener which I think would fire selection events all over again.

A simpler solution would be to use getSelectedRow() in conjunction with e.getValueIsAdjusting(), like:

            public void valueChanged(ListSelectionEvent e)
            {
                if(!e.getValueIsAdjusting()) {
                    System.out.printf("%d - %d : %d\n", e.getFirstIndex(), e.getLastIndex(), table.getSelectedRow());
                }
            }

The table.getSelectedRow() correctly returns the currently selected row (for SINGLE_SELECTION). You can make use of the firstIndex and lastIndex values if you need to do some processing on 'deselecting' an earlier row.