Help for adjusting columns of a JTAble in a Table Model

Question

Hello community,
In order to have a good display of by DataBase in a JTable, I've wrote some code to adjust columns in function of datas. Those datas are displayed with a TableModel ( which I've declared in a class JDBCAdapter ).
When I start my application, I call adjustColumns(), and all is great but when I add information to my DB and display it, the columns of my JTable return to default width...
So I want to incorporate my function adjustColumns in my TableModel, and I need help...
     void adjustColumns()
     // Ajuste les colonnes aux donnes pour que tout soit visible
     int nbRow,nbCol;
     nbRow = JTable1.getRowCount();
     nbCol = test.getColumnCount();
     for ( int i = 0; i < nbCol; i++ )
     com.sun.java.swing.table.TableColumn column = null;
     column = JTable1.getColumnModel().getColumn(i);
     int dataLength = 0;
     for ( int j = 0; j< nbRow; j++ )
     FontMetrics fm;
     int dataLengthTmp;
     String valueTable;
     fm = JTable1.getFontMetrics(JTable1.getFont());
     if ( test.getValueAt(j, i) == null )
     System.out.println("Valeur nulle...");
     dataLengthTmp = 0;
     else
     valueTable = test.getValueAt(j, i).toString();
     dataLengthTmp = fm.stringWidth(valueTable);
     System.out.println(valueTable + " = " + dataLengthTmp);
     if ( dataLengthTmp > dataLength )
     dataLength = dataLengthTmp;
     if ( dataLength != 0 )
column.setWidth(dataLength + 5);
else
column.sizeWidthToFit();
JTable1.setModel(test);
JTable1.repaint();
import java.util.Vector;
import java.sql.*;
import com.sun.java.swing.table.AbstractTableModel;
import com.sun.java.swing.event.TableModelEvent;
public class JDBCAdapter extends AbstractTableModel {
Connection connection;
Statement statement;
ResultSet resultSet;
String[] columnNames = {};
Vector rows = new Vector();
ResultSetMetaData metaData;
public JDBCAdapter(String url, String driverName,
String user, String passwd) {
try {
Class.forName(driverName);
System.out.println("Ouverture de la connexion a la base de donnee...");
connection = DriverManager.getConnection(url, user, passwd);
statement = connection.createStatement();
catch (ClassNotFoundException ex) {
System.err.println("Cannot find the database driver classes.");
System.err.println(ex);
catch (SQLException ex) {
System.err.println("Cannot connect to this database.");
System.err.println(ex);
public void executeQuery(String query) {
if (connection == null || statement == null) {
System.err.println("There is no database to execute the query.");
return;
try {
resultSet = statement.executeQuery(query);
metaData = resultSet.getMetaData();
int numberOfColumns = metaData.getColumnCount();
columnNames = new String[numberOfColumns];
// Get the column names and cache them.
// Then we can close the connection.
for(int column = 0; column < numberOfColumns; column++) {
columnNames[column] = metaData.getColumnLabel(column+1);
// Get all rows.
rows = new Vector();
while (resultSet.next()) {
Vector newRow = new Vector();
for (int i = 1; i <= getColumnCount(); i++) {
newRow.addElement(resultSet.getObject(i));
rows.addElement(newRow);
// close(); Need to copy the metaData, bug in jdbc:odbc driver.
fireTableChanged(null); // Tell the listeners a new table has arrived.
catch (SQLException ex) {
System.err.println(ex+" query = "+query);
public void executeUpdate(String query) {
if (connection == null || statement == null) {
System.err.println("There is no database to execute the query.");
return;
try {
statement.executeUpdate(query);
// close(); Need to copy the metaData, bug in jdbc:odbc driver.
fireTableChanged(null); // Tell the listeners a new table has arrived.
catch (SQLException ex) {
System.err.println(ex+" query = "+query);
public void close() throws SQLException {
System.out.println("Fermeture de la connection a la base de donnee... Bye !");
resultSet.close();
statement.close();
connection.close();
protected void finalize() throws Throwable {
close();
super.finalize();
// Implementation of the TableModel Interface
// MetaData
public String getColumnName(int column) {
if (columnNames[column] != null) {
return columnNames[column];
} else {
return "";
public Class getColumnClass(int column) {
int type;
try {
type = metaData.getColumnType(column+1);
catch (SQLException e) {
return super.getColumnClass(column);
switch(type) {
case Types.CHAR:
case Types.VARCHAR:
case Types.LONGVARCHAR:
return String.class;
case Types.BIT:
return Boolean.class;
case Types.TINYINT:
case Types.SMALLINT:
case Types.INTEGER:
return Integer.class;
case Types.BIGINT:
return Long.class;
case Types.FLOAT:
case Types.DOUBLE:
return Double.class;
case Types.DATE:
return java.sql.Date.class;
default:
return Object.class;
public boolean isCellEditable(int row, int column) {
try {
return metaData.isWritable(column+1);
catch (SQLException e) {
return false;
public int getColumnCount() {
return columnNames.length;
// Data methods
public int getRowCount() {
return rows.size();
public Object getValueAt(int aRow, int aColumn) {
Vector row = (Vector)rows.elementAt(aRow);
return row.elementAt(aColumn);
public String dbRepresentation(int column, Object value) {
int type;
if (value == null) {
return "null";
try {
type = metaData.getColumnType(column+1);
catch (SQLException e) {
return value.toString();
switch(type) {
case Types.INTEGER:
case Types.DOUBLE:
case Types.FLOAT:
return value.toString();
case Types.BIT:
return ((Boolean)value).booleanValue() ? "1" : "0";
case Types.DATE:
return value.toString(); // This will need some conversion.
default:
return "\""+value.toString()+"\"";
public void setValueAt(Object value, int row, int column) {
try {
String tableName = metaData.getTableName(column+1);
// Some of the drivers seem buggy, tableName should not be null.
if (tableName == null) {
System.out.println("Table name returned null.");
String columnName = getColumnName(column);
String query =
"update "+tableName+
" set "+columnName+" = "+dbRepresentation(column, value)+
" where ";
// We don't have a model of the schema so we don't know the
// primary keys or which columns to lock on. To demonstrate
// that editing is possible, we'll just lock on everything.
for(int col = 0; col<getColumnCount(); col++) {
String colName = getColumnName(col);
if (colName.equals("")) {
continue;
if (col != 0) {
query = query + " and ";
query = query + colName +" = "+
dbRepresentation(col, getValueAt(row, col));
System.out.println(query);
System.out.println("Not sending update to database");
// statement.executeQuery(query);
catch (SQLException e) {
// e.printStackTrace();
System.err.println("Update failed");
Vector dataRow = (Vector)rows.elementAt(row);
dataRow.setElementAt(value, column);
Thanks to help me.

Answer 1

Hi,
OK. I have read your code sample again. It looks like the JDBCAdapter class is reloading table data in the executeQuery method. Why not call adjustColumns at the end of this method after the new rows and columns are loaded? Perhaps it also should be called at the end of executeUpdate. Have you tried doing that?
I would still set
JTable1.setAutoCreateColumnsFromModel (false); to prevent Java from readjusting the size automatically at some other time.
regards,
Terry