how to list an items to a JTable

Question

I am trying to create a checkout simulation for my coursework. So every time I search for an item I can retrieve it from the database and display it on the JTable. However, once I add an item to the list and try to add another item the old item get replaced by the new item.

I am trying to list all the item in the JTable, this is my code:

DBConnection db = new  DBConnection();
    try {

        ResultSet rs =  DBConnection.stmt.executeQuery("SELECT ID, MESSAGE FROM STOCK WHERE ID = '"+ id + "'"); 

        jTable1.setModel(DbUtils.resultSetToTableModel(rs));




    }
    catch (Exception e){
        System.out.println(e);

    }`

Answer 1

The main problem is DbUtils.resultSetToTableModel(rs), which is creating a brand new TableModel, filled with the contents of the ResultSet, this, when applied to the JTable is replacing the view with the contents of the TableModel.

In order to be able to update the table, you need to update the existing TableModel...

There are a few ways this might be achieved, by the simplest might be to use a DefaultTableModel...

Start by creating a class instance field of a DefaultTableModel...

public class ... {
    //...
    private DefaultTableModel stockTableModel;
    //...

Then, when you want to load the stock items, you will need to initialise the model, if it's not already initialised, and then add the new results to it...

DBConnection db = new DBConnection();
try (ResultSet rs = DBConnection.stmt.executeQuery("SELECT ID, MESSAGE FROM STOCK WHERE ID = '" + id + "'")) {

    if (stockTableModel == null) {
        stockTableModel = new DefaultTableModel();
        for (int col = 0; col < metaData.getColumnCount(); col++) {
            stockTableModel.addColumn(metaData.getColumnName(col + 1));
        }
        jTable.setModel(model);
    }

    while (rs.next()) {
        Vector rowData = new Vector(metaData.getColumnCount());
        for (int col = 0; col < metaData.getColumnCount(); col++) {
            rowData.add(rs.getObject(col + 1));
        }
        stockTableModel.addRow(rowData);
    }

} catch (SQLException exp) {
    exp.printStackTrace();
}

Take a look at How to Use Tables and JDBC Database Access for more details

Answer 2

You can create a custom data model that allows you to insert new rows to table.

lets say that you have class, that can hold your query result fields.

public class Item implements Comparable<Item> {

    private Long id;
    private String message;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String value) {
        this.message= value;
    }

    @Override
    public int compareTo(Item o) {
        return id.compareTo(o.id);
    }

}

and it needs to go to table, which has been defined somewhere like:

JTable table =new JTable();

this is a data model to your table

public class Model extends AbstractTableModel {

    private List<Item> items;

    public Model() {
        items = new ArrayList<>();
    }

    @Override
    public int getRowCount() {
        return items.size();
    }

    @Override
    public int getColumnCount() {
        return 3;
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        if (rowIndex > items.size() - 1 || rowIndex < 0) {
            return "";
        }
        final Item get = items.get(rowIndex);
        switch (columnIndex) {
            case 0:
                return get.getId();
            case 1:
                return get.getMessage();
        }
        return "";
    }

    @Override
    public String getColumnName(int column) {
        switch (column) {
            case 0:
                return "id";
            case 1:
                return "message";
        }
        return "";
    }

    public void addItem(Item i) {
        items.add(i);
        fireTableDataChanged();
    }

    public void addItem(ResultSet rs) {
        try {
            Item item = new Item();
            item.setId(rs.getLong("ID"));
            item.setMessage(rs.getString("MESSAGE"));
            items.add(item);
            fireTableDataChanged();
        } catch (SQLException ex) {
            Logger.getLogger(Model.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

now create field

Model myModel=new Model();

and set it as a table model

table.setModel(myModel);

now every time you need to add something to table, just use our table model (i created two methods to insert data public void addItem(Item i) and public void addItem(ResultSet rs).

this should work. If you need to clear table sometimes, just add pubic method public void clear() to your model, in which you will clear items list and call fireTableDataChanged();. It is necessary, otherwise GUI will not refresh.

EDIT

Your code should be like

    DBConnection db = new DBConnection();
    try {

        ResultSet rs = DBConnection.stmt.executeQuery("SELECT ID, MESSAGE FROM STOCK WHERE ID = '" + id + "'");

        myModel.add(rs);

    } catch (Exception e) {
        System.out.println(e);

    }

Answer 3

Just add a row to your JTable Model every time you have your result...

refer to this SO question

 DefaultTableModel model = (DefaultTableModel) jTable1.getModel();
        model.addRow(new Object[]{"Column 1", "Column 2", "Column 3"});

or in your case

DefaultTableModel model = (DefaultTableModel) jTable1.getModel();
            model.addRow(new Object[]{searchResultData});