Java JFrame method pack()

I have a frame with 4 JPanels and 1 JScrollPane, the 4 panels are in border layout north, east, south, west and the scrollpane in the center.

I have been 开发者_JAVA技巧trying to get the pack method for a frame functioning but when run you just get the title bar of the window.

Any Ideas?

    JFrame conFrame;
    JPanel panel1;
    JPanel panel2;
    JPanel panel3;
    JPanel panel4;
    JScrollPane listPane;
    JList list;
    Object namesAr[];
    ...
    ...
    ...
    namesAr= namesA.toArray();
    list = new JList(namesAr); 
    list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
    list.setVisibleRowCount(-3);
    list.addListSelectionListener(this);

    listPane = new JScrollPane(list);

    panel1 = new JPanel();
    panel2 = new JPanel();
    panel3 = new JPanel();
    panel4 = new JPanel();

    conFrame.setLayout(new BorderLayout());

    panel1.setPreferredSize(new Dimension(100, 100));
    panel2.setPreferredSize(new Dimension(100, 100));
    panel3.setPreferredSize(new Dimension(100, 100));
    panel4.setPreferredSize(new Dimension(100, 100));

    panel1.setBackground(Color.red);
    panel2.setBackground(Color.red);
    panel3.setBackground(Color.red);
    panel4.setBackground(Color.red);

    conFrame.pack();

    conFrame.add(panel1, BorderLayout.NORTH);
    conFrame.add(panel2, BorderLayout.EAST);
    conFrame.add(panel3, BorderLayout.SOUTH);
    conFrame.add(panel4, BorderLayout.WEST);
    conFrame.add(listPane, BorderLayout.CENTER);
    conFrame.setVisible(true);

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You need to add the panels to the frame "before" you do the pack() otherwise there is nothing to pack.

Also, the default layout for a frame is the BorderLayout.