JTable, verifying data before changing cell value

Question

I am trying to trap erroneous dataentry into a JTable. I have some fields which are populated by objects which are a subclass of Number. My original though was to trap the data entry at the setValueAt method and verify it there; however, if I enter alpha characters into the cell, it never gets to setValueAt. Any ideas?

Answer 1

The easy fix was to short circuit getColumnClass to return the class of string. The constructor doesn't bomb and I can trap it at the setValueAt() method in my table model.
This is a database application which displays information from a three table join. I have written methods to set all of the master values to the editted values.
Basic idea is to create Hashmaps keyed off of the unique keys for each row of each master table. A vector is placed in a hashmap for each unique key. Each row with that key is then placed in the vector. If a cell from a master is updated, it is easy to grab the key, then grab the vector of all of the rows with that key in it, and update all of the associated rows.
Not sure if anyone else will find it useful, but here it is.
package com.cessna.ewt.bay;
import com.cessna.ewt.util.WeightNumber;
import com.cessna.ewt.util.WeightEmployee;
import java.awt.Toolkit ;
import java.util.Vector;
import javax.swing.JLabel ;
import javax.swing.table.AbstractTableModel;
import javax.swing.JOptionPane;
import java.awt.Color;
import java.util.HashMap;
* Table Model for the Bay application
public class BayTableModel extends AbstractTableModel{
public BayTableModel(WeightEmployee nUser) {
this(); user = nUser;
public BayTableModel()
{    super();
changed = false;
data = new Vector();
for (int iloop = 0; iloop < 20; iloop++) {
     data.add(new BayRecord());     }
public BayTableModel(Vector nData) {
super();
changed = false;
data = nData;
public int getColumnCount() {    
return BayRecord.VISABLE_COLUMN_COUNT ;
public int getRowCount() {    
return data.size();
public int getPreferredColumnWidth(int col) {
return COLUMN_WIDTH[col];
public Object getValueAt(int row, int col) {
BayRecord dataRecord = (BayRecord) data.get(row);
return dataRecord.get(col);
}public String getColumnName(int column) {
return BayRecord.COLUMN_NAMES[column];
public Class getColumnClass(int c) {
if(c == BayRecord.FS) {
System.out.println("DEBUG: GET COLUMN CLASS FOR FS");
return BayRecord.getColumnClass(c);
public boolean isCellEditable(int row, int col) {
if (user != null) {
if (user.canApprove()) {
//System.out.println(user + " can approve.");
return true;
//System.out.println(user + " can not approve.");
return false;
public Color getNonEditableBackground(int col) {
return Color.lightGray;
public Color getEditableBackground(int col) {
return Color.white;
public void setUser(WeightEmployee nUser) {
user = nUser;
public void setValueAt(Object aValue, int row, int column) {
System.out.println("into setValueAt");
BayApplet applet = BayApplet.bayApplet;
BayRecord dataRecord = (BayRecord) data.get(row);
String oldValue = dataRecord.get(column).toString();
String newValue = aValue.toString();
//Don't do anything if it hasn't changed     
if ( newValue.compareTo(oldValue) == 0 ) return;
// Do data validation here
switch ( column) {
case (BayRecord.BAY ):
case (BayRecord.BAY_DESCRIPTION ) :
     //update for the entire bay
     updateTable(column,dataRecord.get(BayRecord.EWTBMX_ID).toString(),newValue);
     dataRecord.setBayChanged(true);
     break;
case (BayRecord.SUBBAY_DESCRIPTION ) :
//update for all records associated with this subbay
          dataRecord.setSubBayChanged(true);
     updateTable(column,dataRecord.get(BayRecord.EWTSB_ID).toString(),newValue);
     break;
case (BayRecord.FS ) :
case (BayRecord.BL ) :
case (BayRecord.WL ) :
System.out.println("new value = " + newValue);
try {
Float.parseFloat(aValue.toString());
catch (Exception e) {
          JOptionPane.showMessageDialog(applet
     , e
, "BayTableModel.setValueAt(...) Format Error"
, JOptionPane.ERROR_MESSAGE) ;
return; // input value cannot convert to number
WeightNumber tempNumber =new WeightNumber(newValue,WeightNumber.CG_FORMAT );
dataRecord.set(column,tempNumber);
dataRecord.setBayPointChanged(true);
break;
default: if ( newValue.compareTo(oldValue) != 0 ) {
dataRecord.set(column,aValue);
applet.setModified(true);
* Updates all of the bay discriptions for table
public void updateTable (int column, String key ,String newValue ){
HashMap tempMap;
switch(column) {
case BayRecord.BAY :
case BayRecord.BAY_DESCRIPTION :
     tempMap = bayMap;
     break;
case BayRecord.SUBBAY_DESCRIPTION :
     tempMap = subBayMap;
     break;
default: return; }
// Does the master relationship exist?     
if (! tempMap.containsKey(key)){
     return;
if ( tempMap.get(key) == null) return;
// get the vector that is associated with this key
// associated with key
Vector tempVector = (Vector)tempMap.get(key);
for (int iloop = 0;iloop < tempVector.size();iloop++) {
     BayRecord tempRecord = (BayRecord) tempVector.get(iloop);
     tempRecord.set(column,newValue);
* Returns the alignment of the specified <I>col</I> in the table.
public int getAlignment(int col){
return (COLUMN_ALIGNMENT[col]) ;
public boolean isChanged () {
return changed;
public void setChanged (boolean nChanged) {
changed = nChanged;
public void updateData(Vector nData){
data.removeAllElements();
bayMap = new HashMap();
subBayMap = new HashMap();
WeightNumber ewtbmxID ;
WeightNumber ewtsbID ;
for (int iloop = 0; iloop < nData.size(); iloop++){
BayRecord tempRecord = (BayRecord)nData.get(iloop);
data.add(tempRecord);
addToMaps(tempRecord);;
* Places record hashmaps for easy access
private void addToMaps(BayRecord nRecord) {
// has ewtbmx_id been set?
if (nRecord.get(BayRecord.EWTBMX_ID) == null){
     return;
// is there a bayMap?
if (bayMap == null) {
     bayMap = new HashMap(); }
WeightNumber ewtbmxID = (WeightNumber) nRecord.get(BayRecord.EWTBMX_ID);
Vector bayVector;
//Does the vector for this key exist?
if (bayMap.containsKey(ewtbmxID.toString() )) {
bayVector = (Vector) bayMap.get(ewtbmxID.toString());
else {
     bayVector = new Vector();
bayMap.put(ewtbmxID.toString(),bayVector );
bayVector.add(nRecord );
if (nRecord.get(BayRecord.EWTSB_ID) == null) return;
// is there a subBayMap?
if (subBayMap == null) {
     subBayMap = new HashMap(); }
WeightNumber ewtsbID = (WeightNumber) nRecord.get(BayRecord.EWTSB_ID);
Vector subBayVector;
if (subBayMap.containsKey(ewtsbID.toString() )) {
subBayVector = (Vector) subBayMap.get(ewtsbID.toString());
else {
subBayVector = new Vector();
subBayMap.put(ewtsbID.toString(),subBayVector );
subBayVector.add(nRecord );
* Array of column widths for all displayed columns in the JTable.
public static final int COLUMN_WIDTH[] = {30,200,200,40,40,40};
* Array of column alignments for all displayed columns in the JTable.
private static final int COLUMN_ALIGNMENT[] = {    JLabel.LEFT, JLabel.LEFT, JLabel.LEFT    ,  JLabel.RIGHT, JLabel.RIGHT, JLabel.RIGHT} ;
private Vector data;
private WeightEmployee user;
//This map will contain references to
//Rows in the JTable associated with unique bays
//If someone changes a bay on one line, it will change it
//for all lines associated with that bay.
private HashMap bayMap;
private boolean changed;
//This map will contain references to
//Rows in the JTable associated with unique subbays
//If someone changes a subbay on one line, it will change it
//for all lines associated with that bay.
private HashMap subBayMap;
public static final String SOURCE = "$Source: /apps/csna/javaSource/com/cessna/ewt/weight/RCS/WeightTableModel.java,v $";
public static final String REV = "$Revision: 1.1 $";}