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Populate combobox of table cell with different value based on selection of table row in java

I want to populate the combo box with the value from database based on the selection of table row, it works, but only when I select the different cell of the row then select required combo box cell. But if I select the combobox cell of another row, it shows previous items, and after selecting one of them, if I again click on the combobox it will populate with fresh values. I want the fresh values be populated when I click on row or even combo box cell. Please help.
The code is given below:-
String columnName[] = { "Date","Voucher ID","Voucher No","Amount","VOUCHER_NARRATION","Exp. Head" };
String dataValues[][] = {};
voucherTable=new JTable(dataValues,columnName);
voucherTable.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
ListSelectionModel list=voucherTable.getSelectionModel();
voucherTable.setSelectionModel(list);
list.addListSelectionListener(new ListSelectionListener(){
public void valueChanged(ListSelectionEvent lt) {
try {
voucherid=voucherTable.getValueAt(voucherTable.getSelectedRow(),1).toString();
System.out.println(voucherid);
comboBox.removeAllItems();
TableColumn road=voucherTable.getColumnModel().getColumn(5);
voucherTable.getColumnModel().getColumn(5).setCellEditor(new DefaultCellEditor(new VoucherUpdate().getExpHead(voucherid)));
} catch(Exception h) {
System.err.println(h);
return;
}
}
});
public JComboBox getExpHead(String vid) {
String voucherId=vid;
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection conn=DriverManager.getConnection("jdbc:odbc:SARALIFMS","SARALIFMS","O391120SUMAN");
Statement st=conn.createStatement();
ResultSet rs=st.executeQuery("SELECT E.EXP_ID,EXP_HEAD FROM TD_VOUCHER_SUMAN D, MM_PRIA_EXPENDITURE E"
+" WHERE VOUCHER_ID='"+voucherId+"' AND D.ACCOUNT_CODE=E.ACCOUNT_CODE");
while(rs.next()) {
String expHead=rs.getString("EXP_HEAD");
comboBox.addItem(expHead);
}
conn.close();
} catch(Exception e) {
System.out.println(e);
}
return comboBox;
}

it works, but only when I select the different cell of the row then select required combo box cell
When you click on a cell using a combo box as an editor, the editor is invoked BEFORE the selected row has been updated. So this is a timing issue.
One solution is to override the getCellEditor(...) method of the JTable to load the data when the editor is actually invoked. At this point in time the selected row will be updated and you can get the data for the appropriate row.
This approach is demonstrated in this question: https://stackoverflow.com/a/4211552/131872
Note you may want to consider caching the data so you don't do an SQL access every time you edit the cell.

Detecting Cell Click On A Table Row That Is Already Selected

I have a JFrame application that contains a JTabel. The underlying table model is my own class that I made that extends AbstractTableModel. The data in the first column is of type boolean and so I want it to show the value in the form of a checkbox. To do this, I added the following code in my table model getColumnClass method:
#Override
public Class<?> getColumnClass(int columnIndex) {
if (columnIndex == 0) {
return Boolean.class;
} else if (columnIndex == 1) {
....
....
}
This works fine and my table cell looks like the following which is what I want:
The behavior I now want is that when the user clicks on a cell in column 0 of any row I want to toggle the value of On Sale.
My main class listens to selections in the table by implementing ListSelectionListener and overriding the valueChanged method. Inside the valueChanged method I can check the selected column by calling table.getSelectedColumn and checking to see if it's 0 then getting the object at the selected row and toggling the boolean on sale value.
The problem I am running into is that if a particular row is already selected and the user clicks the cell in column 0 for the selected row the valueChanged method is never called and so therefore I never toggle the value.
My quesion is, how do I detect a cell selection/click on a row that is already selected? Should I use a mouse selection listener then determine the cell that was clicked using the location data from the mouse click event?
Thank you.

Have you tried listening to table change instead ? You would need to implement TableModelListener and to have this :
public void tableChanged(TableModelEvent e) {
int row = e.getFirstRow();
int column = e.getColumn();
TableModel model = (TableModel)e.getSource();
String columnName = model.getColumnName(column);
Object data = model.getValueAt(row, column);
...// Do something with the data...
}

GWT DataGrid row selection

I have a GWT DataGrid with a multi-selection model and check-boxes to show selection/select/deselect rows. That's all well and good.
But, I also want to have a second, independent selection model. If a user double-clicks on a row, I want to handle that event, and for the event handler to know which row was double-clicked. The double-clicking should not affect the check-box selection.
I tried this:
final SelectionModel<MyRecord> selectionModel = new MultiSelectionModel...
//Yes I need a MultiSelectionModel
dataGrid.addDomHandler(new DoubleClickHandler() {
public void onDoubleClick(DoubleClickEvent event) {
selectionModel.get??? //no suitable getter for double-clicked
}
}, DoubleClickEvent.getType());
But ran into a dead-end when I found now way to get the double-clicked row in the event handler. One way would be to register both a Multi- and Single- selection model, but doubt DataGrid will support that.
Neither can I work out how to get the clicked row from the DoubleClickEvent object.
I have implemented a button cell with a FieldUpdater. This works, but it's not ideal.
Any suggestions?

If I understand correctly you want to get the index of the row.
You could do it like this: (this way you'll get the "Real" index)
AbstractSelectionModel<T> selectionModel = (AbstractSelectionModel<T>)dataGrid.getSelectionModel();
ArrayList<Integer> intList = new ArrayList<Integer>();
List<Row> list = (List<Row>)_dataProvider.getList();
int i = 0;
for(Row row : list)
{
if( selectionModel.isSelected(row) )
intList.add(i);
i++;
}
UPDATE:
To get only the current row you could do that:
datagrid.getKeyboardSelectedRow()

I'm 3 years too late to the party, but I think the more correct solution would be:
dataGrid.addCellPreviewHandler(new CellPreviewEvent.Handler<YOUR_MODEL_TYPE>() {
#Override
public void onCellPreview(final CellPreviewEvent<YOUR_MODEL_TYPE> event) {
if (BrowserEvents.DBLCLICK.equalsIgnoreCase(event.getNativeEvent().getType())) {
int row = event.getIndex();
doStuff(row); // do whatever you need the row index for
}
}
});

What is the best way to listen for changes in JTable cell values and update database accordingly?

I'm building and app with multiple JTables and I need to detect when cell value change occurs so I can update it in the database. I tried TableModelListener and overriding tableChanged, but it fires only when I click away (click on another row) after I have edited a cell.
Any other way to do this?

You can implement the CellEditorListener interface, as shown in this example. Note that JTable itself is a CellEditorListener.
It may also be convenient to terminate the edit when focus is lost, as shown here:
table.putClientProperty("terminateEditOnFocusLost", true);
More Swing client properties may be found here.

I'm agreeing with #mKorbel - unless all your input is checkboxes and dropdowns, you're going to want to wait until the cell editing is stopped (you don't want to commit to the database every time a letter is typed in a textbox).
If the problem is that it's not committing after focus has gone to another component, add a FocusListener that stops editing the table when focus is lost on the table:
Example:
final JTable table = new JTable();
table.addFocusListener(new FocusAdapter() {
#Override
public void focusLost(FocusEvent e) {
TableCellEditor tce = table.getCellEditor();
if(tce != null)
tce.stopCellEditing();
}
});

I use the enter key so everytime a user hit enter the cell will update.
DefaultTableModel dtm = new DefaultTableModel(data, columnNames);
JTable table = new JTable(dtm);
table.addKeyListener(new KeyAdapter() {
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_ENTER) {
int row = table.getSelectedRow();
int column = table.getSelectedColumn();
// resul is the new value to insert in the DB
String resul = table.getValueAt(row, column).toString();
// id is the primary key of my DB
String id = table.getValueAt(row, 0).toString();
// update is my method to update. Update needs the id for
// the where clausule. resul is the value that will receive
// the cell and you need column to tell what to update.
update(id, resul, column);
}
}
});

This is also handy if you want to stop the editing on an event handler from selection change or save button.
if (table.isEditing())
table.getCellEditor().stopCellEditing();

Get TableCell content for SQL query

I'm writing an SQL CRUD application and stuck on the delete button problem. I have a table with 4 columns and a delete button in the fifth. To make an SQL query I need to get info from these 4 columns. I can get a row number and a column name, how to get cell content on row/column intersection?

Assuming the fifth column has a custom cell factory that puts the delete button in its custom TableCell, this delete button can own an action like:
btnDelete.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
param.getTableView().getSelectionModel().select(getIndex());
Person item = personTable.getSelectionModel().getSelectedItem();
if (item != null) {
// Logic of deleting current record here
System.out.println(item.getName());
}
}
});
The full sscce, Putting button into the table column more elegantly.