Java program doesn't show swing elements until resized?

Question

Could anyone please explain why this may be happening? Image is here Image I couldn't upload because I'm a new user.

setTitle("jNote");
    pack();
    setVisible(true);
    setLayout(new BorderLayout());
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Image icon = Toolkit.getDefaultToolkit().getImage("jNote.png");
    setIconImage(icon);

Answer 1

Usually GUI size can be suggested by the contents. If called after the components are added, pack() will cause the GUI to be the minimum size it needs to display them.

import java.awt.BorderLayout;
import javax.swing.*;

public class JNote {

    public JComponent getGui(int rows, int cols) {
        JPanel p = new JPanel(new BorderLayout(2,2));

        p.add(new JLabel("1"), BorderLayout.LINE_START);
        JTextArea ta = new JTextArea(rows, cols);
        JScrollPane sp = new JScrollPane(
                ta,
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
                JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        p.add(sp);
        p.add(
            new JLabel("Rows: " + rows + "    " + "Columns: " + cols),
            BorderLayout.PAGE_END);

        return p;
    }

    public static void main(String[] args) {
        Runnable r = new Runnable(){
            public void run() {
                int cols = 20;
                JNote jNote = new JNote();
                for (int rows=6; rows>0; rows-=2) { 
                    JFrame f = new JFrame("jNote " + rows + "x" + cols);
                    f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
                    f.setLocationByPlatform(true);
                    f.add(jNote.getGui(rows, cols));

                    f.pack();
                    f.setVisible(true);
                }
            }
        };
        SwingUtilities.invokeLater(r);
    }
}

Answer 2

When setting dimensions via preferred sizes, you must call pack() in order to apply your preferred sizes. Resizing a frame packs it as well, hence your observations.

// component initializations
yourFrame.pack();