DefaultTableModel Overview

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The

DefaultTableModel
class is a subclass of the
AbstractTableModel
. As the name suggests it is the table model that is used by a JTable when no table model is specifically defined by the programmer. The DefaultTableModel stores the data for the JTable in a
Vector
of
Vectors
.

Although the

Vector
is a legacy Java collection it is still supported and there is no issue with using it unless the additional overhead caused by using a synchronized collection is a problem for your Java application.

The advantage of using the

DefaultTableModel
over a custom
AbstractTableModel
is you don't have to code the methods like add, insert or delete rows and columns. They already exist to change the data held in the
Vector
of
Vectors.
This makes it a quick and easy table model to implement.

Import Statement

import javax.swing.table.DefaultTableModel;

Constructors

The

DefaultTableModel
class has six constructors. Each can be used to populate of the
DefaultTableModel
in different ways.

The first constructor takes no arguments and creates a

DefaultTableModel
which has no data, zero columns and zero rows:
DefaultTableModel defTableModel = DefaultTableModel();

The next constructor can be used to specify the number of rows and columns of a

DefaultTableModel
with no data:
DefaultTableModel defTableModel = DefaultTableModel(10, 10);

There are two constructors that can be used to create a

DefaultTableModel
with column names and a specified number of rows (all containing null values). One uses an ​
Object
array to hold the column names, the other ​a
Vector
:
String[] columnNames = {"Column 1","Column 2","Column 3"};
DefaultTableModel defTableModel = DefaultTableModel(columnNames, 10);

or

DefaultTableModel defTableModel = DefaultTableModel(columnNames, 10);

Finally there are two constructors used to populate the

DefaultTableModel
with row data along with column names. One used
Object
arrays, the other
Vectors
:
Object[][] data = {{1,1,1},{2,2,2},{3,3,3},{4,4,4}};
String[] columnNames = {"Column 1","Column 2","Column 3"};
DefaultTableModel defTableModel = DefaultTableModel(data, columnNames);

or

Vector rowData = new Vector();
rowData.add(1);
Vector> data = new Vector>();
data.add(0, rowData);
Vector columnNames = new Vector();
columnNames.add("Column 1");
DefaultTableModel defTableModel = DefaultTableModel(data, columnNames);

Useful Methods

To add a row to the

DefaultTableModel
use the
addRow
method along with the row data to add:
Object[] newRowData = {5,5,5,5};
defTableModel.addRow(newRowData);

To insert a row use the

insertRow
method, specifying the row index to insert and the row data:
Object[] insertRowData = {2.5,2.5,2.5,2.5};
defTableModel.insertRow(2,insertRowData);

To delete a row use the

removeRow
method, specifying the row index to delete:
defTableModel.removeRow(0);

To get a value in a table cell use the

getValueAt
method. For example, if the data at row 2, column 2 contains an int:
int value = tabModel.getValueAt(2, 2);

To set a value in a table cell

setValueAt
method with the value to set along with the row and column index:
defTableModel.setValueAt(8888, 3, 2);

Usage Tips

If a

JTable
is created using the constructor that is passed a two-dimensional array containing the row data and an array containing the column names:
Object[][] data = {{1,1,1},{2,2,2},{3,3,3},{4,4,4}};
String[] columnNames = {"Column 1","Column 2","Column 3"};
JTable exampleJTable = new JTable(data, columnNames);

then the following cast will not work:

DefaultTableModel dft = (DefaultTableModel)exampleJTable.getModel();

A runtime

ClassCastException
will be thrown because in this instance the
DefaultTableModel
is declared as an anonymous inner class in the
JTable
object and cannot be cast. It can only be cast to the
TableModel
interface. A way around this is to create your own
DefaultTableModel
and set it to be the model of the
JTable
:
JTable exampleJTable = new JTable();
DefaultTableModel defTableModel = new DefaultTableModel(data, columnNames);
exampleJTable.setModel(defTableModel);

Then the

DefaultTableModel
defTableModel
can be used to manipulate the data in the
JTable
.

To see the

DefaultTableModel
in action have a look at the DefaultTableModel Example Program.