Dynamic rows for dynamic data

Question

Hi,
Can i have a JTable in which i create number of rows depending on the data i retreive frm the database, and also increase the number of rows on some kind of event.
For example:
I have to enter into a JTable names of students who are being admitted to a school, i have a specific format in the UI with fields(columns) like Name, Age, Sex. I give them a 5 rows as default. As the user comes to the 5th and 5th cell, tht is last cell of the table, as soon as the user presses Enter key another row/s should appear. And also if i am retreiving frm the database, depending on a query like give me names of students who are all females, then i dont know the number of rows required, therefore deciding dynamically or on-the-fly the number of rows required.
Please if you can help me, tht will be great.
Thank You.
Ehsaan
p.s-If u need more information pls do write.

Answer 1

Here's an example of a model you may want to use. It allows you to add or subtract rows, as needed. It starts with 0 rows - in this case.
You need to define another class TableRecord, which basically is contains the data to insert into a row.
Hope this helps.
public class FileModel extends AbstractTableModel
public boolean isEditable = false;
protected static int NUM_COLUMNS = 3;
// initialize number of rows to start out with ...
protected static int START_NUM_ROWS = 0;
protected int nextEmptyRow = 0;
protected int numRows = 0;
static final public String first= "First";
static final public String second= "Second";
static final public String third= "Third";
static final public String columnNames[] = {"FIrst", "Second", "Third"};
// List of data
protected Vector data = null;
public FileModel()
data = new Vector();
public boolean isCellEditable(int rowIndex, int columnIndex)
// The 3rd column or Value field is editable
if(isEditable)
if(columnIndex > 1)
return true;
return false;
public Class getColumnClass(int c)
return getValueAt(0, c).getClass();
* Retrieves number of columns
public synchronized int getColumnCount()
return NUM_COLUMNS;
* Get a column name
public String getColumnName(int col)
return columnNames[col];
* Retrieves number of records
public synchronized int getRowCount()
if (numRows < START_NUM_ROWS)
return START_NUM_ROWS;
else
return numRows;
* Returns cell information of a record at location row,column
public synchronized Object getValueAt(int row, int column)
try
FileRecord p = (FileRecord)data.elementAt(row);
switch (column)
case 0:
return (String)p.first;
case 1:
return (String)p.second;
case 2:
return (String)p.third;
catch (Exception e)
return "";
public void setValueAt(Object aValue, int row, int column)
FileRecord arow = (FileRecord)data.elementAt(row);
arow.setElementAt((String)aValue, column);
fireTableCellUpdated(row, column);
* Returns information of an entire record at location row
public synchronized FileRecord getRecordAt(int row) throws Exception
try
return (FileRecord)data.elementAt(row);
catch (Exception e)
throw new Exception("Record not found");
* Used to add or update a record
* @param tableRecord
public synchronized void updateRecord(FileRecord tableRecord)
String file = tableRecord.file;
FileRecord p = null;
int index = -1;
boolean found = false;
boolean addedRow = false;
int i = 0;
while (!found && (i < nextEmptyRow))
p = (FileRecord)data.elementAt(i);
if (p.file.equals(file))
found = true;
index = i;
} else
i++;
if (found)
{ //update
data.setElementAt(tableRecord, index);
else
if (numRows <= nextEmptyRow)
//add a row
numRows++;
addedRow = true;
index = nextEmptyRow;
data.addElement(tableRecord);
//Notify listeners that the data changed.
if (addedRow)
nextEmptyRow++;
fireTableRowsInserted(index, index);
else
fireTableRowsUpdated(index, index);
* Used to delete a record
public synchronized void deleteRecord(String file)
FileRecord5 p = null;
int index = -1;
boolean found = false;
int i = 0;
while (!found && (i < nextEmptyRow))
p = (FileRecord5)data.elementAt(i);
if (p.file.equals(file))
found = true;
index = i;
} else
i++;
if (found)
data.removeElementAt(i);
nextEmptyRow--;
numRows--;
fireTableRowsDeleted(START_NUM_ROWS, numRows);
}