Editing cell restrictions of a column in a JTable / TableModel

I am looking to modify the way cell input is handled in my JTable. Currently I am using a DefaultTableModel as seen below.

 DefaultTableModel model = new DefaultTableModel() {

                @Override
                public boolean isCellEditable(int row, int col) {
                    return col == 1 || col == 2 || col == 6;
                }

                @Override
                public Class getColumnClass(int col) {
                    if (col == 6) {
                        return Integer.class;
                    } else {
                        return String.class;
                    }
                }

            };

With this code column 6 forces the user to input an Integer. I would like to take this further by not allowing the number to be outside of a range (e.g. 1-100) and also for the field to never be empty (The column will have data in it prior to user interaction). I have read the docummentation but cannot seem to find anything that manages the behaviour of column types. Thanks!

You would need to create a custom editor.

The following example demonstrates and editor that forces the data to be 5 characters:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;
public class TableFiveCharacterEditor extends DefaultCellEditor
{
private long lastTime = System.currentTimeMillis();
public TableFiveCharacterEditor()
{
super( new JTextField() );
}
public boolean stopCellEditing()
{
JTable table = (JTable)getComponent().getParent();
try
{
String editingValue = (String)getCellEditorValue();
if(editingValue.length() != 5)
{
JTextField textField = (JTextField)getComponent();
textField.setBorder(new LineBorder(Color.red));
textField.selectAll();
textField.requestFocusInWindow();
JOptionPane.showMessageDialog(
table,
"Please enter string with 5 letters.",
"Alert!",JOptionPane.ERROR_MESSAGE);
return false;
}
}
catch(ClassCastException exception)
{
return false;
}
return super.stopCellEditing();
}
public Component getTableCellEditorComponent(
JTable table, Object value, boolean isSelected, int row, int column)
{
Component c = super.getTableCellEditorComponent(
table, value, isSelected, row, column);
((JComponent)c).setBorder(new LineBorder(Color.black));
return c;
}
private static void createAndShowUI()
{
JTable table = new JTable(5, 5);
table.setPreferredScrollableViewportSize(table.getPreferredSize());
JScrollPane scrollPane = new JScrollPane(table);
//  Use a custom editor
TableCellEditor fce = new TableFiveCharacterEditor();
table.setDefaultEditor(Object.class, fce);
JFrame frame = new JFrame("Table Five Character Editor");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( scrollPane );
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}

You would need to modify the editor to make sure:

1. the data is an Integer by using the Integer.parseInt(...) method
2. that the Integer value is in your desired range

Edit:

> how can I apply this to influence one column rather than the entire table.

You can add the editor to the TableColumn:

table.getColumnModel().getColumn(...).setCellEditor(...);

Overriding the behaviour of the DefaultCellEditor achieves the desired outcome.

            DefaultCellEditor editor = new DefaultCellEditor(new JTextField()) {
@Override
public boolean stopCellEditing() {
JTable table = (JTable) getComponent().getParent();
try {
String value = (String) getCellEditorValue();
if (Integer.parseInt(value) < 1) {
JTextField textField = (JTextField) getComponent();
textField.setBorder(new LineBorder(Color.red));
textField.selectAll();
textField.requestFocusInWindow();
return false;
}
} catch (NumberFormatException ex) {
return false;
}
return super.stopCellEditing();
}
};

Then added to the desired column of the table.

table.getColumnModel().getColumn(6).setCellEditor(editor);

Edit: The behaviour inside the if statement will not occur if a NumberFormatException is thrown, you may want to put the same lines of code within the catch.