JPanel as TreeCellRenderer not shown

Question

Hello all,
I'm experiencing a rather strange problem using a custom JPanel as a TreeCellRenderer for a JTree. Basically I needed to show a JLabel and an JTextArea inside a JScrollPane for each Node in my JTree. So I created a subclass of JPanel, implementing the TreeCellRenderer interface and registered it on the tree. The problem I experience is, that nothing is shown in my tree. Instead of the JPanel and its components I see a white space exactly the size of the JPanel, but no components in it. When I try to add my custom JPanel to a regular other panel, it shows up perfectly. My source code for the renderer looks like this (the text is statically provided at the moment, so each node should display the same amount of information):
public class XMLTreeCellRenderer extends JPanel implements TreeCellRenderer
    private javax.swing.JLabel jLabel1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private void initComponents()
        jPanel1 = new javax.swing.JPanel();
        jLabel1 = new javax.swing.JLabel();
        jPanel2 = new javax.swing.JPanel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jLabel1.setOpaque(true);
        jLabel1.setHorizontalAlignment(SwingConstants.LEFT);
        jLabel1.setVerticalAlignment(SwingConstants.CENTER);
        setLayout(new java.awt.BorderLayout(10, 10));
        setOpaque(true);
        setBackground(new java.awt.Color(255, 255, 255));
        setMinimumSize(new java.awt.Dimension(140, 100));
        jPanel1.setLayout(new java.awt.BorderLayout(10, 10));
        jPanel1.setBackground(new java.awt.Color(255, 255, 255));
        jPanel1.setPreferredSize(new java.awt.Dimension(140, 20));
        jLabel1.setBackground(new java.awt.Color(255, 255, 255));
        jLabel1.setText("Testvalue");
        jPanel1.add(jLabel1, java.awt.BorderLayout.CENTER);
        add(jPanel1, java.awt.BorderLayout.NORTH);
        jPanel2.setLayout(new java.awt.BorderLayout(10, 10));
        jPanel2.setPreferredSize(new java.awt.Dimension(140, 80));
        jScrollPane1.setBorder(new javax.swing.border.EtchedBorder());
        jTextArea1.setEditable(false);
        jTextArea1.setToolTipText("Current Value");
        jScrollPane1.setViewportView(jTextArea1);
        jPanel2.add(jScrollPane1, java.awt.BorderLayout.CENTER);
        add(jPanel2, java.awt.BorderLayout.CENTER);
        validate();
        repaint();
    public XMLTreeCellRenderer()
        super();
        initComponents();
     * Returns the component that contains a rendered version of this node
     * @see javax.swing.tree.TreeCellRenderer#getTreeCellRendererComponent(javax.swing.JTree, java.lang.Object, boolean, boolean, boolean, int, boolean)
    public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus)
        LineBorder m_border;
        m_border = new LineBorder(Color.RED, 1, true);
        if (selected)
            setBorder(m_border);
        else
            setBorder(null);
        return this;
}This is really driving me crazy. If I'm trying to return a simple JLabel, everything works ok, but whenever I want to show the JPanel, nothing happens.
Thanks in advance for any suggestions,
Sven

Answer 1

Hello,
no, I did not set a preferred size for the border; I did as shown in the code:
        m_border = new LineBorder(Color.RED, 1, true);
        if (selected)
            setBorder(m_border);
        else
            setBorder(null);
        }The only thing that I do is setting a minimum size.
Sven