我在选择何时使用MouseListener对象时遇到麻烦

Question

Sorry for the bad title, I couldn't think of a better way to phrase it.

Anyway, I need my JLabel to have a different MouseListener when there are more than 2 objects in the same container. I'm trying to make a calendar program so there are 42 panels that these labels are added to. When there are too many labels, I want the last one to be able to open a window that will show the rest.

Right now, when there is more than 2 labels, the last label has both the mouseListener from inside the if (number_of_labels[index-7]) statement and from the if (mouseListenerActive) statement.

This method is called in a loop elsewhere. If you need to see anything else, I'll add it.

public static void insertLabel(String text, final int index, Color colour) {
    final JLabel label = new JLabel();

    label.setText(text);
    label.setOpaque(true);
    label.setBackground(colour);

    mouseListenerActive = true;

    if (number_of_labels[index-7] == 2) {
        label.setBackground(Color.RED);
        JLabel last_label = (JLabel) calendar_boxes[index].getComponent(2);
        last_label.setText("     ▼");
        last_label.setForeground(Color.WHITE);
        last_label.setBackground(Color.BLACK);

        mouseListenerActive = false;
        last_label.addMouseListener(new MouseListener() {
            @Override public void mouseExited(MouseEvent e) {}
            @Override public void mouseEntered(MouseEvent e) {}
            @Override public void mouseReleased(MouseEvent e) {}
            @Override public void mousePressed(MouseEvent e) {}

            @Override
            public void mouseClicked(MouseEvent e) {
                //int day = index - (position of last day - number of days in current month)
                int day = index - (Integer.parseInt(monthDataNode.getChildNodes().item(Main.year-1900).getChildNodes().item(Main.month_index-1).getTextContent()) - Constants.month_lengths[Main.month_index-1]);
                calendarList.open(day, Main.month_index-1, Main.year);
            }
        });
    } else if (number_of_labels[index-7] > 2) {
        return;
    }

    if (mouseListenerActive) {
        label.addMouseListener(new MouseListener() {
            @Override public void mouseExited(MouseEvent e) {}
            @Override public void mouseEntered(MouseEvent e) {}
            @Override public void mouseReleased(MouseEvent e) {}
            @Override public void mousePressed(MouseEvent e) {}

            @Override
            public void mouseClicked(MouseEvent e) {
                //int day = index - (position of last day - number of days in current month)
                int day = index - (Integer.parseInt(monthDataNode.getChildNodes().item(Main.year-1900).getChildNodes().item(Main.month_index-1).getTextContent()) - Constants.month_lengths[Main.month_index-1]);
                calendarEdit.open(day, Main.month_index-1, Main.year, label.getText());
            }
        });
    }

    calendar_boxes[index].add(label, new AbsoluteConstraints(19, 6+(15*number_of_labels[index-7]), 40, 12));
    number_of_labels[index-7]++;
}

Answer 1

In your code, before you add the second MouseListener, remove the first. As you are using anonymous classes and don't have a reference to the original MouseListener, use the following:

MouseListener existingListener = last_label.getMouseListeners()[0];
last_label.removeMouseListener(existingListener);