JList删除按键上的选定项目，然后单击

Question

My task is to enable removing Jlist selected elements when alt is pressed and jlist is clicked. I did this by adding mouse listener to my jlist:

list.addMouseListener(new MouseAdapter(){
        public void mouseClicked(MouseEvent e) {
            java.util.List selectedItems = list.getSelectedValuesList();
            if (e.isAltDown()){
                for (Object o : selectedItems){
                    cm.removeElement(o); //cm is my custom model
                }
            }
        }
    });

My issue is that when there are two elements selected and I click the list with alt pressed only nearest element gets selected and is removed then. I have no clue how to remove several elements with this input combination.

Answer 1

The problem is that the mouse click clears all the previous selections and then selects the row you just clicked on. So therefore only that row is deleted.

So instead you should be handling a "right mouse" click and then use the right mouse button only for the deletion of the item.

if (e.isAltDown() && SwingUtilities.isRightMouseButton(e)) {

Or if you really want to do this on a left mouse click then you would probably need to use a ListSelectionListener . Every time the selection changes you would need to use the getSelectedValuesList() method and save the List returned from the method. Then in the MouseListener you would access the saved List instead of getting the currently selected List of items.

I don't like this approach because the logic is now contained in two separate listeners. Although I guess you could create a class that implement both the selection listener and the mouse listener.

Answer 2

This is not a perfect answer. But it solves the issue .

I just tried to see how the selection event works. When he selection happens an Mouse pressed event is triggered and then the Selection happens. So the MouseListeners which are already added to the component are responsible to make the selection. Removing the MouseListeners which are already in place would prevent the selection happen using mouse. So i did this.

        MouseListener[] adapters = list.getMouseListeners();
        for (int i = 0; i < adapters.length; i++) {
            list.removeMouseListener(adapters[i]);
        }

Now user will not be able to do the selection using mouse but he will be make the selection using keyboard. So the below would work.

       list.addMouseListener(new MouseAdapter() {

            @Override
            public void mousePressed(MouseEvent e) {
            java.util.List selectedItems = list.getSelectedValuesList();
            if (e.isAltDown()){
                for (Object o : selectedItems){
                    model.removeElement(o); //cm is my custom model
                }
            }
            }
        });

I think the answer given by camickr , should be followed.