JPanel won't display when I set a spring layout

Question

I have a JFrame with 3 JPanel containers, one on top, the other on the left side and the last one is on the center taking up the rest of the frame. The problem is when I try to set a SpringLayout for the side panel, it won't display on the panel. The frame has the default border layout.

public final class board extends JFrame {

    public final JPanel top = new JPanel();
    public final JPanel side = new JPanel();
    public final JPanel center = new JPanel();

    public board(){

        initComponents();
        initWindow();

    }

    public void initComponents(){

        Font font = new Font("HelvLight", Font.PLAIN, 20);
        Font fontT = new Font("Century Gothic", Font.BOLD, 30);
        SpringLayout layoutT = new SpringLayout(); 
        JSeparator sep = new JSeparator();
        JLabel title = new JLabel("TITLE");
        JLabel calendar = new JLabel("Calendar");
        JButton settings = new JButton("C"); //Add Icon

        title.setFont(fontT);
        calendar.setFont(font);
        title.setForeground(Color.WHITE);
        calendar.setForeground(Color.WHITE);
        sep.setBackground(Color.white);
        sep.setForeground(Color.white);

        //layoutT.putConstraint(SpringLayout.WEST, calendar, 50, SpringLayout.EAST, center);

        top.setLayout(new BorderLayout());
        top.add(settings, BorderLayout.EAST);

        top.add(title, BorderLayout.CENTER); // Not centered
        top.setBackground(Color.decode("#4C004C"));

        center.setBackground(Color.green);

        side.setBackground(Color.decode("#0f001e"));
        side.setLayout(layoutT);
        side.add(calendar, SpringLayout.SOUTH);
        side.add(sep);
    }

    public void initWindow() {
        Toolkit tk = Toolkit.getDefaultToolkit();

        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize((int)  tk.getScreenSize().getWidth() ,
                (int)  tk.getScreenSize().getHeight()
              );
        //setResizable(false);

        add(top, BorderLayout.NORTH);
        add(side, BorderLayout.WEST);
        add(center, BorderLayout.CENTER);

        pack();
        setVisible(true);
    }
}

That's the way it should work for me, but it doesn't.

Answer 1

The problem is when I try to set a SpringLayout for the side panel, it won't display on the panel.

SpringLayout is a complicated layout manager.

    side.setLayout(layoutT);
    side.add(calendar, SpringLayout.SOUTH);

You are not using it correctly.

Read the section from the Swing tutorial on How to Use SpringLayout for working examples.

However, based on the code provided you can probably use one of the other standard layout managers. Maybe a BoxLayout would be easier.