What is the proper relationship, in code, between a table model and the actual database queries?
Inside the addRow() method in the table model, should I place a further call to my database class, which in turn inserts the row into the database? I've illustrated this in the below code snippets.
public class MainPanel extends JPanel
{
...
public MainPanel()
{
personTableModel = new PersonTableModel();
personTable = new JTable(personTableModel);
...
insertButton = new JButton("Insert");
insertButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
String name = nameTextBox.getText();
String address = addressTextBox.getText();
Object[] row = { name, address };
personTableModel.addRow(row); // <--- Add row to model
}
});
}
}
public class PersonTableModel extends AbstractTableModel
{
private List<Object[]> data;
private List<String> columnNames;
PersonDB personDB = new PersonDB();
...
public void addRow(Object[] row)
{
// insert row into 'data'
personDB.addPerson(row); // <---- Call the personDB database class
}
...
}
public class PersonDB
{
public PersonDB()
{
// establish database connection
}
public addPerson(Object[] row)
{
// code that creates a SQL statement based on row data
// and inserts new row into database.
}
...
}
Whether or not you should directly make an insert call depends on some aspects:
Than of course it may be a good idea to directly insert the data into the backing Database.
You should however watch out, that there are two variants of
addRow
and two variants ofinsertRow
.DefaultTableModel
directs calls internally throughinsertRow(int, Vector)
, which would probably be the only function to overwrite, if you want to immediately persist data.If you like the proposed idea of DTOs the examples below may help you.
The Idea is to represent "Entities" or table rows as classes in Java. A DTO is the simplest representation and normally only contains fields with respective getter and setter.
Entities can generically be persisted and loaded through ORM libraries like EclipseLink or Hibernate. Additionally for this table-application the use of DTOs provide a way of storing data not shown to the user in a clean and typed way.
DTO:
DTO based TableModel:
Example-"Application":