侦听JList setSelectedIndex

Question

MyJList myList = new MyJList();
    myList.addListSelectionListener(new ListSelectionListener() {

    @Override
    public void valueChanged(ListSelectionEvent e) {

    if(!e.getValueIsAdjusting()){
        System.out.println("Selected!");
    }
    }
});

. . .

class MyList extends JList{


    public MyList () {
    super();

    this.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); 

    this.setSelectedIndex(0);

   }

}

When I click on list item with mouse, I see message «Selected!».

When program start, this message not shown, but item #0 is selected.

Answer 1

You setSelectedIndex in the constructor

Then after that, add the SelectionListener

when setSelectedIndex is called...there is no Listener

Answer 2

This is exactly what should happen. valueChanged is only called when the user selects the item. setSelectedIndex does not invoke any listeners.

Answer 3

Look at the order of you code:

a) you create the list and set the index to 0
b) you add the ListSelectionListener. Well nothing has changed since you added the listener so no event is fired.

Try adding:

list.setSelectedIndex(1)

after adding the listener to see if the event is fired.