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empty TableModel after instantiating

Newbie seeking help please :-)
I am working on a little project to get familiar with Java desktop development and Database connectivity.
Attached code gives me an empty TableModel after instantiating therefore no data displayed in the JFrame.
Test class is instantiated from the menue of the main window with Test.showFrame();.
package ...
import ...
public class Test extends JPanel {
public Test() {
initializePanel();
}
private void initializePanel() {
// Creates an instance of TableModel
CategoryTableModel tableModel = new CategoryTableModel();
System.out.println(tableModel.getRowCount());
// Creates an instance of JTable with a TableModel
// as the constructor parameters.
JTable table = new JTable(tableModel);
table.setFillsViewportHeight(true);
JScrollPane scrollPane = new JScrollPane(table);
this.setPreferredSize(new Dimension(500, 200));
this.setLayout(new BorderLayout());
this.add(scrollPane, BorderLayout.CENTER);
}
public static void showFrame() {
JPanel panel = new Test();
panel.setOpaque(true);
JFrame frame = new JFrame("test");
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setContentPane(panel);
frame.pack();
frame.setVisible(true);
}
class CategoryTableModel extends AbstractTableModel {
private List<Category> all = null;
private Iterator<Category> iterator = null;
private int tableRowCount;
private TableModel tableModel;
public CategoryTableModel(){
Vector tableData = new Vector();
// TableModel's column names
Vector<String> tableHeaders = new Vector<String>();
tableHeaders.add("Category");
// Database call
all = new ReadCategory().allCategories();
// TableModel's data
for(Object o : all) {
Vector<Object> row = new Vector<Object>();
all.forEach((n) -> row.add(new Category().getName()));
tableData.add(row);
System.out.println("row added");
}
tableRowCount = tableData.size();
tableModel = new DefaultTableModel(tableData, tableHeaders);
System.out.println(tableModel.getRowCount());
}
#Override
public int getRowCount() {
return 0;
}
#Override
public int getColumnCount() {
return 0;
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
return null;
}
}
}
Database call is fetching data via Hibernate and stores data in a .
Thanks for help.

In its most basic form a table model for a JTable defines the columns, the mapping of object to column and holds the data for the JTable to call upon. If we take your current table model and cut it down to fit this basic requirement we get the following.
import java.util.ArrayList;
import java.util.List;
import javax.swing.table.AbstractTableModel;
public class CategoryTableModel extends AbstractTableModel {
private final List<Category> tableData = new ArrayList<>();
public void add(Category cat) {
tableData.add(cat);
fireTableDataChanged();
}
#Override
public String getColumnName(int column) {
String result = "";
if (column == 0) {
result = "Category Name";
}
return result;
}
#Override
public int getRowCount() {
return tableData.size();
}
#Override
public int getColumnCount() {
return 1;
}
#Override
public Object getValueAt(int rowIndex, int columnIndex) {
if (columnIndex == 0) {
return tableData.get(rowIndex).getName();
}
return null;
}
}
Notice that we do not define any data in the model itself. All we define is some storage for the data and the column name of the single column that we require.
I have added an add() method that allows you to add data to the model (you may wish to define remove etc. yourself). When you add or remove data from the model you must always let the JTable know that the data has changed by calling fireTableDataChanged() so that the table can redraw itself.
To use this table model you will need to do
CategoryTableModel model = new CategoryTableModel();
model.add(new Category());
JTable table = new JTable(model);
You can replace the model.add() with a loop that iterates over your data and adds it to the model.

How to add a button inside a table cell in java netbeans? (I am using the drag and drop method.)

I am trying to add a button inside a table cell. I am using the drag and drop method of netbeans since I know nothing about coding and will appreciate if you can teach me to code it. Thanks!

If you are using drag&drop in netbean for swing,
I highly advise you to touch the fundamental of swings , get your hands dirty so that you will know what is going on and how does the code work.
let me run through how you can achieve this. it will consist of 3 classes so that you will have a better understanding on what is going on and it practices oop too but of cause you can modify it to your preferred design pattern.
_main.java
public class _main extends JFrame{
private static final long serialVersionUID = 1L;
// Create new JFrame
_main(){
new JFrame("Main");
setLayout(new BorderLayout());
setSize(500,300);
add(new JLabel("Table Example ", SwingUtilities.CENTER) , BorderLayout.PAGE_START);
// ---------------- Call the method you have created in tableView.java ------------
add(new JScrollPane(new tableView(this).sampleTable()), BorderLayout.CENTER);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
public static void main(String[] args){
//Run Program
new _main();
}
}
tableView.java
public class tableView {
JFrame frame = new JFrame();
public tableView(JFrame frame) {
this.frame = frame;
}
//Create columnTitle & Table Model
String[] columnTitle = { "Data 1", "Data 2", "Data 3", "Buttons " };
DefaultTableModel model = new DefaultTableModel(columnTitle, 0);
public JTable sampleTable(){
JTable _dataTable = new JTable(model) {
#Override
public void updateUI() {
super.updateUI();
setRowHeight(34);
setAutoCreateRowSorter(true);
//------------ Placing button at your desired column ------------
TableColumn column;
column = getColumnModel().getColumn(3);
column.setCellRenderer(new tableModel(frame).new viewRenderer());
column.setCellEditor(new tableModel(frame).new ButtonsEditorView(this));
}
};
DefaultTableCellRenderer centerRenderer = new DefaultTableCellRenderer();
centerRenderer.setHorizontalAlignment(JLabel.CENTER);
//-------- Adding data to your table row , use for loop for multiple data ---------
model.addRow(new Object[]{"1","2","3"});
return _dataTable;
}
}
tableModel.java
public class tableModel extends tableView{
public tableModel(JFrame frame) {
super(frame);
}
class viewButton extends JPanel {
public JButton viewbtnp = new JButton("View");
protected viewButton() {
setOpaque(true);
setFocusable(false);
add(viewbtnp);
}
}
class viewRenderer implements TableCellRenderer {
private final viewButton panel = new viewButton() {
#Override
public void updateUI() {
super.updateUI();
setName("Table.cellRenderer");
}
};
#Override
public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus,
int row, int column) {
panel.setBackground(isSelected ? table.getSelectionBackground() : table.getBackground());
return panel;
}
}
class ViewAction extends AbstractAction {
private final JTable table;
protected ViewAction(JTable table) {
super("view");
this.table = table;
}
#Override
public void actionPerformed(ActionEvent e) {
//--------------------------- Create your own function on what you want the button to do when button is clicked -------------
System.out.println("Clicked ");
}
}
class ButtonsEditorView extends AbstractCellEditor implements TableCellEditor {
protected final viewButton panel = new viewButton();
protected final JTable table;
protected ButtonsEditorView(JTable table) {
super();
this.table = table;
panel.viewbtnp.setAction(new ViewAction(table));
}
#Override
public Component getTableCellEditorComponent(JTable tbl, Object value, boolean isSelected, int row,
int column) {
panel.setBackground(tbl.getSelectionBackground());
return panel;
}
#Override
public Object getCellEditorValue() {
return "";
}
}
}
Output
Hope it helps.
Cheers

How to make JTable with JComboBox respond only on double click instead of single click

So this is the first time I tried using CellEditors for my JTable to embed JComboBox and JSpinner. Everything works fine as expected wherein I can see the values in JComboBox model as well as JSpinner's model values.
However, I noticed that it always displays the JComboBox's values as soon as I make a single click on JTable's column that has the JComboBox.
It's not very user friendly because I think the user would prefer to double click on a JTable's column to get the dropdown box values and select values from it instead of a single click.
How can I change the JComboBox's behaviour to only display itself on double click?
I thought I'd apply a MouseListener to the JComboBox but I don't know what to do next.
Here's what I've written so far.
public class ScheduleDayCellEditor extends DefaultCellEditor{
private JComboBox jcmbDays;
private JTable jtblSchedule;
private DefaultComboBoxModel model;
public ScheduleDayCellEditor(){
super(new JComboBox());
model = new DefaultComboBoxModel(new String[]{"Mon","Tue","Wed","Thu","Fri"});
jcmbDays = new JComboBox(model);
jcmbDays.setEditable(false);
jcmbDays.setSelectedIndex(-1);
jcmbDays.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent e) {
if(e.getClickCount() == 2){
//? ? ? ?
}
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
});
}
#Override
public Component getTableCellEditorComponent(JTable table, Object value, boolean isSelected, int row, int column) {
return jcmbDays;
}
#Override
public Object getCellEditorValue() {
return jcmbDays.getSelectedItem(); //To change body of generated methods, choose Tools | Templates.
}
Here's a screenshot for additional description.
I'd appreciate any help.
Thank you.

If you don't need to extend DefaultCellEditor for some other reason, you can simply invoke its setClickCountToStart() method with a count of 2.
DefaultCellEditor editor = new DefaultCellEditor(jcmbDays);
editor.setClickCountToStart(2);
jcmbColumn.setCellEditor(editor);

Simply override isCellEditable by applying further criterion:
#Override
public boolean isCellEditable(EventObject aAnEvent) {
boolean cellEditable = super.isCellEditable(aAnEvent);
if (cellEditable && aAnEvent instanceof MouseEvent) {
cellEditable = ((MouseEvent) aAnEvent).getClickCount() == 2;
}
return cellEditable;
}

Controlled editing of a row selection in JTable

I have a JTable displaying rows from an SQL database. The table is relatively small (only 4 columns and up to 1000 rows).
I would like to give the user the opportunity to edit any cells in the table but want to avoid restricting it so much so that they must use an edit dialog box (this makes for far easier error checking and validation but is less intuitive)
I have tried a few different ways of controlling edit selections using the valueChanged method of my JTable but haven't had much luck.
I would like each row to be edited and written to the database at the conclusion of editing. I would like that once a cell has been clicked to start the editing of that row, no other rows can be selected until the user has finished editing the row (other rows are grayed out). After editing each cell and pressing enter, the edit selection should jump to the next column in the same row.
Can anyone give pointers on how I can achieve this?
// Create table with database data
table = new JTable(new DefaultTableModel(data, columnNames)) {
public Class getColumnClass(int column) {
for (int row = 0; row < getRowCount(); row++) {
Object o = getValueAt(row, column);
if (o != null){
return o.getClass();
}
}
return Object.class;
}
#Override
public boolean isCellEditable(int row, int col){
return true;
}
#Override
public boolean editCellAt(int row, int column) {
boolean ans = super.editCellAt(row, column);
if (ans) {
Component editor = table.getEditorComponent();
editor.requestFocusInWindow();
}
return ans;
}
#Override
public void valueChanged(ListSelectionEvent source) {
super.valueChanged(source);
if (table!=null)
table.changeSelection(getSelectedRow(), getSelectedColumn()+1, false, false);
}
};
Edit - custom cell editor with table pointer seems to be a start
public class ExchangeTableCellEditor extends AbstractCellEditor implements TableCellEditor {
private JTable table;
JComponent component = new JTextField();
public ExchangeTableCellEditor(JTable table) {
this.table = table;
}
public boolean stopCellEditing() {
boolean ans = super.stopCellEditing();
//now we want to increment the cell count
table.editCellAt(table.getSelectedRow(), table.getSelectedColumn()+1);
return ans;
}
#Override
public void cancelCellEditing() {
//do nothing... must accept cell changes
}
#Override
public Object getCellEditorValue() {
return ((JTextField)component).getText();
}
#Override
public Component getTableCellEditorComponent(JTable arg0, Object value,
boolean arg2, int arg3, int arg4) {
((JTextField)component).setText((String)value);
return component;
}
}

The default renderer and editor is typically adequate for most data types, but you can define custom renderers and editors as needed.
Addendum: I'm unfamiliar with the approach shown in your fragment. Instead, register a TableModelListener with your model, as shown below, and update the database with whatever granularity is warranted. See also How to Use Tables: Listening for Data Changes.
Addendum: #kleopatra is correct about your TableCellEditor. One convenient way to notify listeners is to invoke the super implementation, as shown here. Note that the delegate invokes fireEditingStopped().
/** #see https://stackoverflow.com/questions/9155596 */
public class NewJavaGUI extends JPanel {
private final JTable table;
public NewJavaGUI() {
String[] colNames = {"C1", "C2", "C3"};
DefaultTableModel model = new DefaultTableModel(colNames, 0) {
#Override
public boolean isCellEditable(int row, int col) {
// return your actual criteria
return true;
}
#Override
public Class getColumnClass(int col) {
// return your actual type tokens
return getValueAt(0, col).getClass();
}
};
// Add data; note auto-boxing
model.addRow(new Object[]{"A1", "A2", 42});
model.addRow(new Object[]{"B1", "B2", 42d});
model.addTableModelListener(new TableModelListener() {
#Override
public void tableChanged(TableModelEvent e) {
// DML as indicated
}
});
table = new JTable(model);
this.add(table);
}
private void display() {
JFrame f = new JFrame("NewJavaGUI");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new NewJavaGUI().display();
}
});
}
}

The behaviour you mention can be achieved by forcing your table to start editing again.
First make sure you now yourRow and Column and that you add your own tablecelleditor that extands from the AbstractCellEditor
then add this to your stopCellEditing method:
EventQueue.invokeLater(new Runnable()
{
public void run()
{
yourTable.editCellAt( yourRow, yourColumn+1);
}
});

Adding TableModelListener to AbstractTableModel

I've faced an issue in adding TableModelListener to AbstractTableModel. The program stops working and the JFrame doesn't response for any button-clicking or even closing the JFrame.
What I want is to make a JButton enabled iff the number of rows in myTable is equal or more than 2 rows.
Here is my code ...
My custom Table:
public class MyTable extends JPanel
{
public Main main;
public ArrayList<MyData> lstData;
public JTable table;
public MyTableModel model;
// ...
public MyTable(ArrayList<MyData> lstData, Main main)
{
this.lstData = lstData;
this.main = main;
model = new MyTableModel(lstData);
table = new JTable(model);
// ...
}
// ...
public int getTableSize()
{
return model.getRowCount();
}
public TableModel getModel()
{
return model;
}
public class MyTableModel extends AbstractTableModel
{
protected String[] columnNames = new String[ ] {"#","Name", "Phone Number"};
protected ArrayList<MyData> lstData;
protected Class[] types = new Class[]{String.class, String.class, String.class};
public MyTableModel(ArrayList<MyData> lstData)
{ this.lstData = lstData; }
public void SetData(ArrayList<MyData> lstData)
{ this.lstData = lstData; fireTableDataChanged(); }
#Override
public String getColumnName(int columnIndex)
{ return columnNames[columnIndex]; }
#Override
public Class getColumnClass(int columnIndex)
{ return types[columnIndex]; }
public Object getValueAt(int row, int column)
{
if (row < 0 || row > lstData.size()) return null;
MyData obj = lstData.get(row);
switch(column)
{
case 0: return obj.getID();
case 1: return obj.getName();
case 2: return obj.getPhoneNumber();
default: return null;
}
}
public int getRowCount() { return lstData.size(); }
public int getColumnCount() { return columnNames.length; }
}
}
Main class:
public class Main extends JFrame implements TableModelListener
{
public static ArrayList<myData> lstData;
public static MyTable table;
public static JButton myButton;
public Main()
{
// ...
table = new MyTable(lstData, this);
table.getModel().addTableModelListener(this);
myButton = new JButton();
myButton.setEnabled(false);
// ...
}
// ...
public void tableChanged(TableModelEvent e)
{
int firstRow = e.getFirstRow();
int lastRow = e.getLastRow();
int mColIndex = e.getColumn();
switch(e.getType())
{
case TableModelEvent.INSERT:
if(table.getTableSize() >= 2) myButton.setEnabled(true);
else myButton.setEnabled(false);
break;
case TableModelEvent.DELETE:
if(table.getTableSize() >= 2) myButton.setEnabled(true);
else myButton.setEnabled(false);
break;
}
}
}
Could you help me to solve this issue? Thanks in advance.
EDIT:
The GUI stop responding only if I add or delete elements from the table.
EDIT2:
No errors or exceptions are thrown after I add elements to the table, it's just freezing the gui with no response

basic tutorial about TableModelListener here or here or here
best would be camickr Table Cell Listener that implements deepest funcionalities for Listening in the TableCell

In your MyTableModel class, remove the following line:
protected TableModel model = this;
And also remove the following methods:
public void setModel(TableModel model){
this.model = model;
}
public TableModel getModel() {
return model;
}
You are already implementing a custom table model, there is no need to create that self reference inside of it. When your class is getting instantiated the this variable is not fully initialized and I suspect that is what is causing problems for you. But in any case the code is definitely not needed. Also, in your MyTable class I would recommend changing the getModel() function to defer to your wrapped table variable. Like so:
public TableModel getModel() {
return model.getModel();
}

Thank you guys for your help, I solve this issue by modifying the tableChanged method:
public void tableChanged(TableModelEvent e)
{
if(table.getTableSize() >= 2) myButton.setEnabled(true);
else myButton.setEnabled(false);
}