Card Layout show

Hi,
I am trying to implement the show method, of cardlayout. However i cannot get it to work.

Code:

---

public class Main {

                JFrame guiFrame;
                CardLayout cards;
                JPanel cardPanel;
public static void main(String[] args) {

                        // Use the event dispatch thread for Swing components
                        EventQueue.invokeLater(new Runnable() {

                                @Override
                                public void run() {

                                        try {
                                                new Main();
                                        } catch (IOException e) {
                                                // TODO Auto-generated catch block
                                                e.printStackTrace();
                                        }
                                }
                        });

                }
public Main() throws IOException {
                        guiFrame = new JFrame();

          guiFrame.setSize(800, 600);
                cards = new CardLayout();
                cardPanel = new JPanel();
                cardPanel.setLayout(cards);
             
                final JPanel[][] JP = new JPanel[27][2];
                      for (int i = 0; i < JP.length; i++) {
                       
                        JP[i][1] = new JPanel();


                        JP[i][1].setBackground(Color.white);
                        cardPanel.add(JP[i][1]);

                }

        JButton [][] Category = new JButton[5][2];
                for (int i = 0; i < Category.length; i++) {
                        JButton bRec = new JButton();
                        Category[i][1] = bRec;
                        JP[1][1].add(bRec);
                        bRec.setFont(FirstFont);
                        bRec.setBorder(BorderFactory.createLineBorder(Color.black));
                        bRec.setBackground(BackGround);
                        bRec.setForeground(Color.white);

                    ButQuestions500[0][1].addActionListener(new ActionListener() {
                        @Override
                        public void actionPerformed(ActionEvent event) {
                                cards.show(cardPanel, "JP5");
                               
                        }
                });
                guiFrame.add(cardPanel, BorderLayout.CENTER);// add to frame in center
                guiFrame.add(backTab, BorderLayout.SOUTH);
                guiFrame.setVisible(true);
                    }// Showing only problematic area

---

Whether i use JP[5][1].getName()
or the current method it will not flip to that card.

Thanks

I think you are trying to use (call) the show() method of CardLayout, rather than implement it.

Note, from its API docs, that it wants as argumets both the container with the layout, and the name of the thing to show.

Code:

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cards.show(cardPanel, "JP5");

---

As far as I can tell you just made up the name "JP5": it isn't the actual name of any of the panels. So nothing will happen.

Quote:

---

Whether i use JP[5][1].getName()
or the current method...

---

I guess you mean you tried

Code:

---

cards.show(cardPanel, JP[5][1].getName());

---

but, again, you never gave JP[5][1] a name, so it doesn't have one to return with getName().

Try giving the panel a name. Do this at the time you add the panel to the container. There's an example of this on the How to Use CardLayout page of Oracle's Tutorial.

... and I meant to add: follow standard Java coding conventions and begin variables with a lowercase letter. Eg category. And make the variables descriptive of what they are.

I tried setting the name of a Panel and then retrieving it, but still nothing.

Code:

---

JP[5][1].setName("Hello");
...
cards.show(cardPanel, "Hello");

---

or

Code:

---

JP[5][1].setName("Hello");
...
cards.show(cardPanel, JP[5][1].getName());

---

I understand now, when adding to the cardPanel i have to add a name
cardPanel.add (JP[i][1],"JP"+i)

Setting the name as part of adding the panel to the container, then showing the panel using the same name (as illustrated on that tutorial page) works for me. But that involved changing your code somewhat as ButQuestions500 is not declared anywhere.

Fwiw, I added the button listener to bRec. Also I put some text into each of the bRec buttons, and added some content to each of the panels added to the JP array so I could see what gui changes were taking place. But none of that is of much use to you: better, I think if you post compilable, runnable code. You can remove the stuff that has no bearing on the problem (fonts, backgrounds etc), but the resulting code should be runnable if others are to see the problem.

Given what you tried: did you read the tutorial example? and see how the components were added to the container? Eg the String BUTTONPANEL was used both for adding and showing. (For showing the string was obtained via the combobox.) You don't have to use static final strings, but you should use strings that the container (and its layout manager) know about in order to successfully switch to a given panel by name.

---

It is worth changing the variable names for legibility. It becomes a habit after a while and, hence, effortless.

Quote:

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Originally Posted by dd2308

I understand now, when adding to the cardPanel i have to add a name
cardPanel.add (JP[i][1],"JP"+i)

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Yes, exactly! Well done.

Post back if that change isn't enough.