CODEWITHSUNDEEP
javaeclipseswingjlistlistselectionlistener
codebender
codebender

Reputation: 455

ListSelectionListener wrong index

I just wanted to see which element is getting selected, and change other labels and texfields on the frame as per the index. My code is as follows:

    list = new JList(listModel);
    list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    list.setLayoutOrientation(JList.VERTICAL);

    list.addListSelectionListener(new ListSelectionListener() {
        public void valueChanged(ListSelectionEvent e) {
            System.out.println(e.getLastIndex());
        }
    });

When I clicked first element output: 0 0 After clicking the second element: 1 1 After that I tried to click first element again, but this time output was 1 1 again. When I tried with 25 elements, selecting last element and after that click first element and output is 23 23. Is it about event's problem or it's about my code?

Upvotes: 1

Views: 944

Answers (1)

Jordi Castilla
Jordi Castilla

Reputation: 26981

The behaviour you get is the standard one, if you want to have different one, create your own SelectionListener that considers also getValueIsAdjusting().

class SharedListSelectionHandler implements ListSelectionListener {
    public void valueChanged(ListSelectionEvent e) {
        ListSelectionModel lsm = (ListSelectionModel)e.getSource();

        int firstIndex = e.getFirstIndex();
        int lastIndex = e.getLastIndex();
        boolean isAdjusting = e.getValueIsAdjusting();
        output.append("Event for indexes "
                      + firstIndex + " - " + lastIndex
                      + "; isAdjusting is " + isAdjusting
                      + "; selected indexes:");

        if (lsm.isSelectionEmpty()) {
            output.append(" <none>");
        } else {
            // Find out which indexes are selected.
            int minIndex = lsm.getMinSelectionIndex();
            int maxIndex = lsm.getMaxSelectionIndex();
            for (int i = minIndex; i <= maxIndex; i++) {
                if (lsm.isSelectedIndex(i)) {
                    output.append(" " + i);
                }
            }
        }
        output.append(newline);
    }
}

Find here explanation of this example.

Upvotes: 3

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