How to make first row of JList unselectable like JTable

[Shaan Shar]

Hi I am using a JList to show a number of data in tabular format. I can't use JTable(that's my first constraint).

Here is the code I have used. Everything is working fine except the first row is selectable yet. Can anyone share an idea how to make first row un-selectable(e.g. like a header in JTable).

public class DisplayJList{

  public void addElements() {
    // first number is number of rows, second is number of columns
    columnData = new String[4][3];
    // static setting of String[][]
    columnData[0][0] = "Name";
    columnData[0][1] = "Age";
    columnData[0][2] = "Time";
    // dynamic setting of String[][]
    for (int i = 1; i < 4; i++) {
      columnData[i][0] = "Testing";
      columnData[i][1] = String.valueOf(i * 13);
      Calendar c = new GregorianCalendar();
      columnData[i][2] = ((Date) c.getTime()).toString();
    }
  }

  static class MyCellRenderer extends JPanel implements ListCellRenderer {
    private static final long serialVersionUID = 1L;
    private final JLabel labels[];

    private int coloumnCount;
    MyCellRenderer(int coloumnCount) {
      super();
      this.coloumnCount = coloumnCount;
      setLayout(new GridLayout(1, coloumnCount));
      labels =new JLabel[coloumnCount];
      for(int i=0;i<coloumnCount;i++){
        labels[i] = new JLabel();
        labels[i].setOpaque(true);
        add(labels[i]);
      }
    }

    public Component getListCellRendererComponent(JList list, Object value, int index,
        boolean isSelected, boolean cellHasFocus) {
      for(int i=0;i<coloumnCount;i++){
        final String data = ((String[]) value)[i];
        labels[i].setText(data);
      }
      if (isSelected) {
        for(int i=0;i<coloumnCount;i++){
          labels[i].setBackground(list.getSelectionBackground());
          labels[i].setForeground(list.getSelectionForeground());
        }
      } else {
        for(int i=0;i<coloumnCount;i++){
          labels[i].setBackground(list.getBackground());
          labels[i].setForeground(list.getForeground());
        }
      }
      setEnabled(list.isEnabled());
      setFont(list.getFont());
      return this;
    }
  }
 public static void main(String[] args){
   // Add the code here to display this list
    JList list =  new JList();
    list.setListData(columnData);
    list.setCellRenderer(new MyCellRenderer(3));
    // add this list in any JFrame and display it.
 }
}

Thanks>

[Rob Spoor]

Ankur Sharma wrote:I can't use JTable(that's my first constraint).

Why not?

Can anyone share an idea how to make first row un-selectable(e.g. like a header in JTable).

With JTable, the header is actually a separate component, of type JTableHeader.

If you add your JTable to a simple JPanel, you'll notice that the table header is absent - you have to add it manually. JTable has special support for JScrollPane for adding the header automatically, but JScrollPane is the only one.

[Brian Cole]

Ankur Sharma wrote:Hi I am using a JList to show a number of data in tabular format.

... Can anyone share an idea how to make first row un-selectable(e.g. like a header in JTable).

It seems like a strange thing to want to do, but try this:

    list.setSelectionModel(new DefaultListSelectionModel() {
        public void setSelectionInterval(int i, int j) {
            if (i != 0 || j != 0) {
                if (i == 0) i = 1;
                if (j == 0) j = 1;
                super.setSelectionInterval(i, j);
            }
        }
        public void addSelectionInterval(int i, int j) {
            if (i != 0 || j != 0) {
                if (i == 0) i = 1;
                if (j == 0) j = 1;
                super.addSelectionInterval(i, j);
            }
        }
        public void setLeadSelectionIndex(int i) {
            if (i != 0) super.setLeadSelectionIndex(i);
        }
        public void setAnchorSelectionIndex(int i) {
            if (i != 0) super.setAnchorSelectionIndex(i);
        }
    });

You should probably check the ListSelectionModel API to make sure I haven't missed a method.

The other thing you could do is for the first line of your getListCellRendererComponent() method do if (index == 0) isSelected = false;
That wouldn't change if the top element could be selected or not, but it would be drawn as unselected even when selected, which is almost as good. It's not as clean, but it may suit your needs.

[Darryl Burke]

I would suggest adding a JLabel as the scroll pane's header view component.

import javax.swing.*;
import javax.swing.border.BevelBorder;

public class ListWithHeader {
   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         
         @Override
         public void run() {
            new ListWithHeader().makeUI();
         }
      });
   }

   public void makeUI() {
      Object[] data = new Object[20];
      for (int i = 0; i < data.length; i++) {
         data[i] = "Item " + i;
      }
      JList list = new JList(data);
      JScrollPane scrollPane = new JScrollPane(list);
      JLabel label = new JLabel("Header", JLabel.CENTER);
      label.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
      scrollPane.setColumnHeaderView(label);
      
      JFrame frame = new JFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.add(scrollPane);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }
}