Name: boT120536 Date: 01/04/2001


java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)


I have a program that switches JTable TableModels on the fly. My JTable also
uses a default cell renderer, which adjusts the sizes of the rows of the
JTable.

If I start with a table model with 2 rows, then switch to one with more than 2,
I still only see 2 in the table. I will never see more than 2, no matter how
many additional ones may be in my table model.

This is because the JTable's private value, rowModel (which holds row sizes),
does not get reset when you do a setModel. It keeps the row sizes in an array,
which doesn't grow when the table model changes....

The following code illustrates this. Compile and run it, you will see table
labeled "two-row table" with 2 rows. Click the "Switch" button below. The
label switches to "three-row table", but there are still only 2 rows. If you
do not set the custom renderer, or if you do not adjust the row heights in the
renderer, the switch button functions as expected. But the renderer is useless
if it cannot adjust the heights of the rows!!

import javax.swing.table.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Hashtable;


public class test extends JFrame {

   DefaultTableModel tm2;
   DefaultTableModel tm3;
   JTable table;

   public test() {

      table = new JTable();

      String[] tm2head = {"2-row header"};
      String[] tm3head = {"3-row header"};
      String[][] tm2body = {{"first row"},{"second row"}};
      String[][] tm3body = {{"first row"},{"second row"},{"third row"}};

      tm2 = new DefaultTableModel(tm2body,tm2head);
      tm3 = new DefaultTableModel(tm3body,tm3head);

      table.setModel(tm2);

      // Commenting out the below line makes this program work!!
      table.setDefaultRenderer(Object.class,new TextCellRenderer(table));

      JButton button = new JButton("switch");
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            if (table.getModel()==tm2)
               table.setModel(tm3);
            else
               table.setModel(tm2);
         }
      });

      JScrollPane sp = new JScrollPane(table);

      getContentPane().add(sp,BorderLayout.CENTER);
      getContentPane().add(button,BorderLayout.SOUTH);
      pack();
      setVisible(true);

   }



   public static void main(String[] args) {
      new test();
   }



       private class TextCellRenderer extends JTextArea implements
TableCellRenderer {

         private Hashtable rowHeights = new Hashtable();
         private Color selBackground;
         private Color selForeground;
         private Color background;
         private Color foreground;

         public TextCellRenderer(JTable table) {
           setEditable(false);
           setLineWrap(true);
           setWrapStyleWord(true);
           selBackground = table.getSelectionBackground();
           selForeground = table.getSelectionForeground();
           background = table.getBackground();
           foreground = table.getForeground();
         }

         public Component getTableCellRendererComponent(JTable table,
                                                      Object value,
                                                      boolean isSelected,
                                                      boolean hasFocus,
                                                      int row,
                                                      int column) {

           if (isSelected) {
             setBackground(selBackground);
             setForeground(selForeground);
           }
           else {
             setBackground(background);
             setForeground(foreground);
           }

           if (value instanceof String) {
             setText((String)value);
             // set the table's row height, if necessary
             Integer oldHeight = (Integer)rowHeights.get(new Integer(row));
             Integer newHeight = new Integer(getPreferredSize().height);
             if (oldHeight==null || !oldHeight.equals(newHeight)) {
               rowHeights.put(new Integer(row),newHeight);

               // Commenting out the below line makes this program work!!
               table.setRowHeight(row,newHeight.intValue());
             }
           }
           else
             setText("");
           return this;
         }
       }
}
(Review ID: 109943)
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