将一个JPanel更改为另一个JPanel不会重新绘制更改

Question

I have a main JPanel target in MainFraim and another currentView JPanel, which is added to the target panel. target panel contains buttons with listeners. These listeners are then supposed the change the content of the curretView panel, as demonstrated below:

private JPanel currentPanel;

public void setView(String type) {

    if (type.equals("overall")) {
        this.currentPanel = getOverallView();
        frame.setTitle("BookingCalendar - Overall View");
        frame.validate();
    } else if (type.equals("guest")) {
        this.currentPanel = getGuestView();
        frame.setTitle("BookingCalendar - Room View");
        frame.validate();
    } else if (type.equals("room")) {
        currentPanel.removeAll();
        this.currentPanel = getRoomView();
        frame.setTitle("BookingCalendar - Guest View");
        frame.validate();
    }
}

Every method I call returns new JPanel each time it is called:

JPanel currentPanel = new JPanel(new MigLayout("","20 [grow, fill] 10 [grow, fill] 20", "20 [] 10 [] 20"))

The problem is, whenever I call these methods, the panel won't change. It always stays the same (by default: getOverallView() )

I've tried with invalidate, validate, repaint on both frame, as well as the panel, but no changes occur. Could someone please elaborate more as to what I need to do in order to completely change the content of the panel currentView

Answer 1

You shouldn't be creating a new JPanel() every time. Instead create one for each type of view, and use a CardLayout to switch between them. CardLayout lets you have JPanels that get switched out like cards.

Answer 2

It looks like you're just trying to move pointers around, to make the currentView point to a different panel. What you actually need to do is remove the currentView from the target and then add the new panel.

If this is your 2 panels...

JPanel target = new JPanel();
JPanel currentView = new JPanel();

and you add the currentView to the target like so...

target.add(currentView);

Then to change your panel, you need to remove the existing panel from the target , and add the new one...

target.remove(currentPanel);
currentPanel = new JPanel();
target.add(currentPanel);

Answer 3

另外，如果您不想使用CardLayout，则可以像执行操作一样使JPanel成为新的JPanel，只需调用revalidate（）。