JAVA - Validation in JTable

Question

I am trying to validate a cell in the JTable as soon as the data is entered. I want to make sure that say the correct code is entered in the code column. Could anyone let me know how to do this please?

Thanks

Answer 1

Add a TableModelListener to the TableModel backing the JTable.

Basically:

myJTable.getModel().addTableModelListener(
  new TableModelListener()
  {
    public void tableChanged(TableModelEvent e)
    {
       //Validate
    }
  }

Alternatively, you could mess around with the cell editor. Look into JTable.setCellEditor and TableCellEditor.

Which would be spiritually equivalent to:

class MyCellEditor extends DefaultTableCellEditor
{
   ...
   public boolean stopEditing()
   {
     return isValid();
   }
}

Note that if you intend to give any visual cues back to the user, things get really hairy with custom TableCellEditors. Just a warning.

Answer 2

You should implement a TableCellEditor and perform your validation within the stopCellEditing() method. If validation fails this method should return false. From the Javadoc:

"Tells the editor to stop editing and accept any partially edited value as the value of the editor. The editor returns false if editing was not stopped; this is useful for editors that validate and can not accept invalid entries."

Take a look at the GenericEditor class defined within JTable for an example of this.

One other thing worth looking at: You could always construct a DefaultCellEditor with a JFormattedTextField as a parameter and add an InputVerifier to the text field to prevent entry of invalid data from being committed.