Problem of custom table model

Question

Hi,
i m leaning JTable recently, following is an experimental code which i wrote, it has a custom table model and custom tablecellrenderer, the custom tablecellrender determine the column of # of Years greater or equal than 5 should display color green, less than 5 should display color red, it works well, however, the custom table model should be smart enough to know that the # of Years column contains numbers (which should generally be right aligned and have a particular format), it also should know that the Vegetarian column contains boolean values, which can be represented by check boxes, but it didn't, i don't know why, i have implement a getColumnClass method,
but it seems not work, have i make any mistakes? Any idea? Thanks
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableColumn;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.UIManager;
import java.awt.Color;
import java.util.Vector;
public class CellRenderTestVector extends JFrame {
     protected JTable table;
     protected int width = 100;
     protected MyCustomTableModel model;
     public CellRenderTestVector() {
          JPanel pan0 = new JPanel(new BorderLayout());
          Container contentPane = getContentPane();
          pan0.setPreferredSize(new Dimension(500,200));
          model = new MyCustomTableModel();
          table = new JTable();
          table.setAutoCreateColumnsFromModel(false);
          table.setModel(model);
          table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
                        TableColumn column = null;
          for (int i = 0; i < model.getColumnCount(); i++) {
               DefaultTableCellRenderer renderer = new
                 ColoredTableCellRenderer();
               column = new TableColumn(i,
                          width, renderer, null);
                          table.addColumn(column);
          TableColumn t_column = table.getColumnModel().getColumn(2);
          System.out.println(table.getColumnModel());
          JScrollPane scrollPane = new JScrollPane(table);
          pan0.add(scrollPane, BorderLayout.CENTER);
          contentPane.add(pan0);
            public class ColoredTableCellRenderer extends DefaultTableCellRenderer {
          public void setValue(Object value) {
               Color  m_color;
               Color GREEN = new Color(0, 128, 0);
               Color RED = Color.red;
               if (value instanceof Integer) {
                    Integer m_data = (Integer)value;
                    m_color = m_data.intValue() >= 5 ? GREEN : RED;
                                       setForeground(m_color);
                           setText(m_data.toString());
               else {
                    super.setValue(value);
     public class Columndata {
          protected String m_title;
          public Columndata(String title) {
               m_title = title;
     public class Rowdata {
          protected String fname;
          protected String lname;
          protected String sport_type;
          protected Integer no_year;
          protected Boolean vegetarian;
          public Rowdata(String fn, String ln,
                    String sp, int ny, boolean vg) {
               fname = fn;
               lname = ln;
               sport_type = sp;
               no_year = new Integer(ny);
               vegetarian = new Boolean(vg);
     public class MyCustomTableModel extends AbstractTableModel {
          protected final Columndata m_column[] =
                    {new Columndata("First Name"),
                     new Columndata("Last Name"),
                     new Columndata("Sport"),
                     new Columndata("# of Years"),
                     new Columndata("Vegetarian")
          protected Vector m_vector;
          public MyCustomTableModel() {
               m_vector = new Vector();
               setDefaultData();
          public void setDefaultData() {
               m_vector.removeAllElements();
               m_vector.addElement(new Rowdata("Mary", "Campione",
                                                       "Snowboarding", 5, false));
               m_vector.addElement(new Rowdata("Alison", "Huml",
                                                       "Rowing",3,true));
               m_vector.addElement(new Rowdata("Kathy", "Walrath",
                                                       "Knitting",2, false));
               m_vector.addElement(new Rowdata("Sharon", "Zakhour",
                                                       "Speed reading",20,true));
               m_vector.addElement(new Rowdata("Philip", "Milne",
                                                       "Pool",10,false));
          public int getColumnCount() {
               return m_column.length;
          public int getRowCount() {
               return m_vector==null ? 0 : m_vector.size();
          public String getColumnName(int col) {
               return m_column[col].m_title;
          public Object getValueAt(int nRow, int nCol) {
               if (nRow < 0 || nRow>=getRowCount()) return "";
               Rowdata row = (Rowdata)m_vector.elementAt(nRow);
               switch (nCol) {
               case 0: return row.fname;
               case 1: return row.lname;
               case 2: return row.sport_type;
               case 3: return row.no_year;
               case 4: return row.vegetarian;
               return "";
          public Class getColumnClass(int c) {
               return getValueAt(0, c).getClass();
     public static void createAndShowGUI() {
          try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
          } catch (Exception evt) {}
               JFrame f = new CellRenderTestVector();
               f.setTitle("TableTest");
               f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               f.pack();
             f.setVisible(true);
     public static void main(String[] args) {
          javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
}

Answer 1

You need to write your custom TableCellRenderes/Editors for each type. And don't forget to register your custom renderes via myTable.setDefaultRendere().