Enumerating all controls on JFrame

Question

I am quite new to Java and am trying to set the visible property to false for all JPanels on my JFrame (frame.)

When I execute the following, It returns null to console:

public void mouseClicked(MouseEvent e){
    for (Component c : frame.getComponents()) {
        System.out.println(c.getName());
        if (c instanceof JPanel) { 
            ((JPanel)c).setVisible(false);
        }
    }
    panelDispatch.setVisible(true);
    panelDispatch.requestFocus();
}

What I want it to do is set all the panels visibility to false then set the selected panels visibility to true. 3 JPanels are added to frame.

What am I doing wrong here?

Any help would be greatly appreciated.

Adem: Just null text. I wasn't setting the name field for my panels. — thomas hill, Dec 14 '14 at 22:35

Reimeus · Answer 1 · 2014-12-14T22:18:23.943

3

Components are added to a ContentPane of a JFrame rather than the RootPane. You're seeing null displayed to the console as you probably havent set the name property of the component

for (Component c : getContentPane().getComponents()) {

edited Dec 14 '14 at 22:18

answered Dec 14 '14 at 22:13

Reimeus

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Reimeus: That worked perfectly. Simple replacement. Thank you. – thomas hill Dec 14 '14 at 22:34
So you're advocating that the OP do this over use of a CardLayout? If so, why? – Hovercraft Full Of Eels Dec 14 '14 at 22:34
@HovercraftFullOfEels I don't think that he's suggesting I use this over your suggestion. From what I see he is showing me how to get the name of the components. – thomas hill Dec 14 '14 at 22:36

score 2 · Accepted Answer · edited May 23 '17 at 12:20

I can't tell why you're seeing null, and I'm not sure in what way you're seeing it, a NullPointerException perhaps, but I do know that you appear to be removing the JFrame's contentPane, glassPane and rootPane inadvertently, a dangerous thing to do. Instead just use a CardLayout that should allow you to easily and simply swap your GUI views as this is exactly what CardLayout was built for. Please check out the CardLayout Tutorial for more information.

Edit
For examples of CardLayout-using GUI's, please check out:

This one is unusual in that it uses a CardLayout and has one panel fading into the other panel:

CardLayout showing two panels, flashing.

@Hovercraft Full Of Eels A bit confusing for me but I will start looking into all of this. Thank you for all the info! — thomas hill, Dec 14 '14 at 22:38
@HovercraftFullOfEels I can't thank you enough for the links. TabDemo is EXACTLY how I want my app to look/act. Thanks again! — thomas hill, Dec 14 '14 at 23:16

Enumerating all controls on JFrame

2 Answers2