JButton Appears on One Computer, But Not Others (BorderLayout)

Question

I am new to Swing. I am building a JFrame with a JScrollPane inside it using Eclipse IDE. Inside of the JScrollPane is a JPanel in Border Layout. I tried to add a JButton (called "submitAnswers") to the JFrame using the code below, but for some reason the button only appears at the end of the frame on my computer, but not on other computers (my friend tried it on his Mac and I tried it on a separate Windows OS like mine). Some proposed solutions that I have tried and from other sites that have not worked include:

• Use the pack() method. Reason: since the preferred size of the JPanel is much longer in height than the JFrame (hence I employed a JScrollPane), packing the JFrame only causes the text to be not visible on the desktop.
• Place button on content JPanel. Reason: I don't know. It just wouldn't appear on another desktop computer or my friend's mac computer.
• Use BorderLayout.SOUTH instead of BorderLayout.PAGE_END. Reason: There was absolutely no change. The button would still be visible on my computer, but invisible on others.
• Place button directly on JFrame. Reason: I don't know.

In addition, my JFrame is nested within a static method; hence, I've only included the relevant code for the specific method I'm having issues with.

Has anyone had this issue before? I would really appreciate your insight.

Code:

    public static void createTestPage() {

    JFrame testFrame = new JFrame("testing...1,2,3");

    //Customizes icon to replace java icon
    try {
        testFrame.setIconImage(ImageIO.read(new File("src/icon.png")));
    } catch (IOException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

    //Centers location of introFrame to center of desktop
    Dimension screenDimensions = Toolkit.getDefaultToolkit().getScreenSize();
    testFrame.setLocation(screenDimensions.width / 16,screenDimensions.height / 14);

    //Size and display the introFrame.
    Insets insets = testFrame.getInsets();

    //Format size of screen itself
    testFrame.setSize(1200 + insets.left + insets.right,
                  400 + insets.top + 250 + insets.bottom);

    //Temporarily set screen so that it cannot be resized
    testFrame.setResizable(false);

    //Set background color of testFrame
    testFrame.getContentPane().setBackground(new Color(75, 0, 130));

    testFrame.setLayout(new BorderLayout());

    //Set layout of testFrame
    testFrame.setLayout(new BorderLayout(10, 1));

    //Test content
    JPanel testContentPanel = new JPanel();
    testContentPanel.setBackground(new Color(75, 0, 130));
    testContentPanel.setSize(new Dimension(900,2060));
    testContentPanel.setPreferredSize(new Dimension(900, 2060));

    //Test content pane layout
    testContentPanel.setLayout(new BoxLayout(testContentPanel, BoxLayout.PAGE_AXIS));

    //Create panel to hold instructions text
    JPanel instructionsPanel = new JPanel();
    instructionsPanel.setBackground(new Color(75, 0, 130));
    instructionsPanel.setLayout(new BorderLayout(10,1));

    //Create JPanel for submit answers button
    JPanel submitAnswersPanel = new JPanel(new BorderLayout());
    submitAnswersPanel.setBackground(new Color(75, 0, 130));
    submitAnswersPanel.setVisible(true);

    //Create button to submit personality test answers
    JButton submitAnswers = new JButton("Submit Answers");
    submitAnswers.setVisible(true);
    submitAnswers.setBorder(new EmptyBorder(10, 400, 10, 400));

    //Add submitAnswers button to panel
    submitAnswersPanel.add(submitAnswers);

    //Add submitAnswersPanel to test content panel
    testContentPanel.add(submitAnswersPanel);


        //Create scroll pane to allow for scrollable test (contents cannot fit one page)
    JScrollPane testScrollPane = new JScrollPane();
    testScrollPane.setViewportView(testContentPanel);

    //Get rid of horizontal scroll bar and add vertical scrollbar
    testScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    testScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);

    //Speed up scrolling
    testScrollPane.getVerticalScrollBar().setUnitIncrement(16);

    testFrame.add(testScrollPane);

    //Experiment to show button
    testFrame.setVisible(true);
    }

Answer 1

I've refactored your code a little to use method to create the individual components of the GUI. You can find the full code at this ideone link

What I saw when I first copied your code to my machine was that the only thing visible was the button. So I create all the components in their own methods and then added them to the frame and panels using the Border Layout. This then enabled me to put the instructions in the NORTH sections, the button in the SOUTH section and then the main bits would go in the CENTER section.

One thing to note about the sections: (From the documentation)

The components are laid out according to their preferred sizes and the constraints of the container's size. The NORTH and SOUTH components may be stretched horizontally; the EAST and WEST components may be stretched vertically; the CENTER component may stretch both horizontally and vertically to fill any space left over.

So you should add the component you want to scale in size to the CENTER section.

My main method now looks like this:

public static void main(final String[] args) {
    final JButton submitAnswers = createSubmitAnswersButton();
    final JPanel instructionsPanel = createInstructionsPanel();

    final JPanel testContentPanel = createContentPanel();
    testContentPanel.add(instructionsPanel, BorderLayout.NORTH);
    testContentPanel.add(submitAnswers, BorderLayout.SOUTH);

    final JScrollPane scrollingContentPane = createScrollPaneFor(testContentPanel);

    final JFrame testFrame = createJFrame();
    testFrame.add(scrollingContentPane, BorderLayout.CENTER);

    testFrame.setVisible(true);
}