Override method that toggles 'isSelected' in getListCellRendererComponent

Question

I would like to make my own method that controles when a component is 'isSelected'.

I have a JList containing multiple JPanel. The constructing class of the JPanel extends ListCellRenderer<>.

To show that one of the JList-component (the JPanels) is selected i use;

@Override
public Component getListCellRendererComponent(..., boolean isSelected, ...) {
    if(isSelected){
        setBackground(list.getSelectionBackground());
        setForeground(list.getSelectionForeground());
    } else {
        setBackground(list.getBackground());
        setForeground(list.getForeground());
    }
    return this;
}

I would like a method that keeps a selected item 'selected' eventhough I choose to select another. I understand this can be done by holding down CTRL, but .setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION); does not quite do the trick. I would rather like to select multiple by clicking on them, and deselect by clicking on them.

For this i have worked with the ListSelectionMode, but i cant find a way.

When done the above I would like to implement a method that only selects a component in the list when clicked in a certain area (instead of the whole component which is preset). I have made this method, which returns true if the correct area is clicked, else false. But since I cant figure out how to override the mouseevent that makes the components 'isSelected' this has been tricky.

Here is the code for the method I would like to override the 'isSelected' method;

this.addMouseListener(new MouseAdapter() {
        @Override
        public void mousePressed(MouseEvent evt) {
            if(ActionHandler.mouseClickedPrebuild(evt.getPoint())){
                //This code runs if that special place is clicked!
                //So now the component should be 'isSelected' or
                //deselected if it already was 'isSelected'.
            }
        }
    });

This code is in the constructor of my JList

And the mouseClickedPrebuild method;

public static boolean mouseClickedPrebuild(Point point) {
        int index = theJList.locationToIndex(point);
        Rectangle bounds = theJList.getCellBounds(index,index);
        Point p = bounds.getLocation();
        return ( ... long list of greater than & less than ...);
        //This gives the certain area which is accepted to return true

Answer 1

I solved the issue!

So I get my view showing by running this line;

// UI Class   JScrollPane               Custom JList
UIConstructor.listview.setViewportView(new ListView( -insert ArrayList here- ));

Here is my ListView. The custom DefaultListSelectionModel I used to solve my problem was posted by @FuryComptuers right here;

JList - deselect when clicking an already selected item

I had to make a few changes to the code, since the two methods in the selectionModel will run before my mouseevent. I saved the variabels staticly, so instead of running the code in setSelectionInterval I did it inside my mousePressed.

I then could add the boolean isSelected which returns true, if a curtain area within a specific list element is clicked.

public class ListViewd extends JList {

static boolean isSelected;
static Point point;

static boolean gS = false;
static int in0;
static int in1;

@Override
public Dimension getPreferredScrollableViewportSize() {
    Dimension size = super.getPreferredScrollableViewportSize();
    size.setSize(new Dimension(0,0));
    return size;
}

public ListView(ArrayList<System> items) {

    DefaultListModel<System> list = new DefaultListModel<System>();

    for (System item : items) {
        list.addElement(item);
    }

    this.setSelectionModel(new DefaultListSelectionModel() {

        boolean gestureStarted = false;

        @Override
        public void setSelectionInterval(int index0, int index1) {
            gS = gestureStarted;
            in0 = index0;
            in1 = index1;

            gestureStarted = true;
        }

        @Override
        public void setValueIsAdjusting(boolean isAdjusting) {
            if (!isAdjusting) {
                gestureStarted = false;
            }
        }

    });

    ListSelectionModel selectionModel = this.getSelectionModel();

    addMouseListener(new MouseAdapter() {
        @Override
        public void mousePressed(MouseEvent e) {
            point = e.getPoint();
            isSelected = ActionHandler.mouseClickedPrebuild(point);

            if(!gS && isSelected){
                if (isSelectedIndex(in0)) {
                    selectionModel.removeSelectionInterval(in0, in1);
                } else {
                    selectionModel.addSelectionInterval(in0, in1);
                }
            }
        }
    });

    setModel(list);
    setCellRenderer(new ListModelPrebuild());
}