Java – how to prevent JList from selecting outside the cell boundary?

"Is there any way to prevent JList from selecting the last element when the user clicks the next element on the list?"

This is the question someone asked here, and I have the same question That guy found such a solution (by rewriting processmouseevent ()), but I wonder if there is a better / more elegant way to do this

[Edit]

OK, more details If you have a JList and some spaces are not occupied by any cells / elements, and you click the space, the last element in the JList is selected

For a real example, try the JList swing tutorial example, click the space to see if Rollo is selected

Solution

See https://forums.oracle.com/forums/thread.jspa?threadID=2206996

import java.awt.EventQueue;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.event.InputEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JList;
import javax.swing.JScrollPane;

public class TestJList {
    public static void main(String[] args) {
        EventQueue.invokelater(new Runnable() {
            public void run() {
                JList list = new JList(new Object[] { "One","Two","Three" }) {
                    @Override
                    public int locationToIndex(Point location) {
                        int index = super.locationToIndex(location);
                        if (index != -1 && !getCellBounds(index,index).contains(location)) {
                            return -1;
                        }
                        else {
                            return index;
                        }
                    }
                };

                list.addMouseListener(new MouseAdapter() {

                    @Override
                    public void mouseClicked(MouseEvent e) {
                        JList list = (JList) e.getSource();
                        if (list.locationToIndex(e.getPoint()) == -1 && !e.isShiftDown()
                                && !isMenuShortcutKeyDown(e)) {
                            list.clearSelection();
                        }
                    }

                    private boolean isMenuShortcutKeyDown(InputEvent event) {
                        return (event.getModifiers() & Toolkit.getDefaultToolkit()
                                .getMenuShortcutKeyMask()) != 0;
                    }
                });

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloSEOperation(JFrame.DISPOSE_ON_CLOSE);
                frame.getContentPane().add(new JScrollPane(list));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }
}