Develop Reference

Receiving incorrect values from a JTable

I am trying to retrieve and use values from a JTable after a row has been selected using this code:
#Override
public void valueChanged(ListSelectionEvent e){
TableModel tableModel = this.mainFrame.getViewersTableModel();
this.mainFrame.setViewerButtonsEnabled(
!((Boolean)(tableModel.getValueAt(e.getLastIndex(), 1)))
);
}
In my scenario, the table has one row with a value of true, and another of false.
The very strange thing is that the first time I select a row, the value given is correct, whether it be the row holding true, or the one with false, but any subsequent selections result in getting true, no matter which row I pick.

Well, I fixed it.
Instead of getting the required boolean in my event handler class, I just made a method in the mainFrame class that retrieves the boolean from the table. The issue is now resolved.
Thank you to all who helped.

Java - Updating JTable with fireTableDataChanged();

I have a JTable in my program. I want to update it after clicking JButton.
I wrote this:
DefaultTableModel myTable = new DefaultTableModel(celDatas,celNames);
JTable source = new JTable(myTable){public boolean isCellEditable(int rowIndex, int colIndex) {
return false;}};
JScrollPane pane = new JScrollPane(source);
(...)
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
query = "Select sal FROM EMP";
myTable =(DefaultTableModel)source.getModel();
myTable.fireTableDataChanged();
}
The problem is that id doesn't update my data on JTable.
How to resolve this problem?
EDIT:
JTable is displayed in my guy through JScrollPane.
I make now this:
source = new JTable(myTable){public boolean isCellEditable(int rowIndex, int colIndex) {return false;}};
pane = new JScrollPane(source);
I made also a new void, where is getting datas from database + there I define myTable:
void queryConnection() {
(...)
myTable = new DefaultTableModel(celDatas,celNames);
}
I added a JButton, which update my JTable (when we change the query.
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
query = "Select sal FROM EMP";
queryConnection();
}
}
================================================================================
public class Application2 implements Runnable {
private JTable source;
private JScrollPane pane;
private DefaultTableModel myTable;
private JPanel panel;
private String[][] celDatas = null;
private String[] celNames = null;
public void run() {
(...)
start.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e)
{
if(...) {
query = "Select sal FROM EMP";
queryConnection();
}
}
if(query == null) {
query = "Select * from EMP";
queryConnection();
}
source = new JTable(myTable){public boolean isCellEditable(int rowIndex, int colIndex) {return false;}};
pane = new JScrollPane(source);
pane.setSize(f.getSize().width-60,300);
pane.setLocation(30,20);
panel.add(pane);
f.add(panel);
f.pack();
}
void queryConnection() {
//here is connection and downloading datas
myTable = new DefaultTableModel(celDatas,celNames);
}
I hope that it is right now more convenient? ;)

You don't need to call any fireXXX() methods if you're creating a new TableModel, but rather you mainly need to call these if you're writing your TableModel based on AbstractTableModel (you're not).
Your problem lies elsewhere I think. You seem to be creating a new JTable and adding it to a new JScrollPane. Are you adding these components to your GUI (you don't show)? If so, is the container that you're adding to able to accept new components smoothly? Do you revalidate and repaint the container? Is your newly created JTable being displayed in the GUI?
Or, is there a JTable already displayed in your GUI? If so, perhaps all you want to do is set its model rather create a new JTable. I favor this solution as the easiest.
Edit 1
I would do something like so:
Access Database in a background thread and get information from it.
Create a new DefaultTableModel object filling it with data extracted from the database.
I would not create a new JTable if one already exists. Instead I'd simply call setTableModel(...) on the currently displayed JTable and pass in my newly created DefaultTableModel object.
Then I'd sit back and enjoy the big bucks and other fruits of my success.
Edit 2
Ganjira, for us to be able to best help you, we need to understand the problem better, which is why I've requested either full clarification of your problem or an sscce, of which I've seen neither. My problems with understanding your issues include:
Again, do you have a JTable already displayed in your GUI, and now you're trying to change the data that is displayed in the JTable based on data extracted from a database?
If so, why not simply change the model of the existing JTable rather than create a whole new JTable?
If you don't already have a JTable in the application and now you want to display one, you state that your data is not being displayed but don't show code to help us understand why.
If you can answer the first two questions, we may not need an sscce, but if not, please understand that your current post is no where close to being an sscce, in that we cannot run it, we cannot compile it, it doesn't reproduce your problem for us,... I have to wonder if you've even read the link yet as it explains why all of these conditions are important (that and brevity so as not to drown us in a large amount of unrelated code).
No, it is not required that you post an SSCCE, but if we can't help you based on the text in your question and your code snippets, it does offer a better chance of allowing us to understand the problem and find a solution for you.
Edit 3
You state:
JTable's been already in GUI, because it shows the 'beginning of the program'. After clicking JButton I want to change values in JTable. It doesn't change the model of the existing JTable - it doesn't change nothing.
And this confuses me as the best solution is one I've been suggesting all along -- Don't make a new JTable, but instead create a new DefaultTableModel and change the model for the existing JTable. You've yet to mention why you're not trying this, or if you have tried it, how it's not working for you.

set focus for all fields

I noticed I can use getName() as part of the trick.
What is java.awt.Component.getName() and setName() used for?
But I don't really have a clue where to start. What type of listener should I use (assuming the textfield / or box is currently blinking / selected)
This is my previous question, and thank you for the help guys.
How do I use requestFocus in a Java JFrame GUI?
I realize that for each component (Textfield) that I am creating, I have to insert a statement like requestFocus (or using transferFocus).
Is it possible to apply this policy to all the fields???
I have several textfields and ComboBox. The problem I hit is that I don't want to write methods for every single field / box.
For example, I write a method like this
private JTextField getFirstNameEntry() {
.... do something
}
because my instructor writes his program like this
private JPanel getJContentPane() {
jContentPane = new JPanel();
jContentPane.setLayout(new java.awt.FlowLayout(FlowLayout.LEADING));
jContentPane.add(makeLabel(" First Name *", 100, 20));
jContentPane.add(getFirstNameEntry(), null);
jContentPane.add(makeLabel(" Middle Initial", 100, 20));
jContentPane.add(getMiddleInitialEntry(), null);
// etc
return jContentPane;
However, to save redundancy (that was my motive at first), say I have a box, I can simply add the following code inside the method above: getJContentPane()
titleBox = new JComboBox(new String[]{"Mr.","Mrs.","Ms.","Dr.","Prof.","Rev."});
jContentPane.add(titleBox);
But doing this, I still need to create a method to do addItemListener
private void setComboBoxFocus() {
titleBox.addItemListener(
new ItemListener(){
public void itemStateChanged(ItemEvent e){
if(e.getStateChange() == ItemEvent.SELECTED)
{
String titleSelected = titleBox.getSelectedItem().toString();
System.out.println(titleSelected);
titleBox.transferFocus();
}
}
});
}
However, this doesn't really save redundancy at all. If I have more than one ComboBox to be added, I would have to write another similar method. In fact, even in the case with one ComboBox (titleBox), I would still end up with writing a method for titleBox.
So my question is: is there a way to write a general method that can call focus to all (maybe one for ComboBox type)?
Thank you and sorry for the long post.

Why not take a JComboBox argument to your setComboBoxFocus() method, which allows you to set that listener to any JComboBox you may have? Like so:
private void setComboBoxFocus(JComboBox box) {
box.addItemListener(
new ItemListener(){
public void itemStateChanged(ItemEvent e){
if(e.getStateChange() == ItemEvent.SELECTED)
{
String titleSelected = box.getSelectedItem().toString();
System.out.println(titleSelected);
box.transferFocus();
}
}
});
}

JLists with a set of objects

i am making a twitter client (desktop application) in Java, i am using twitter4j API also. i have managed to do the search for tweets and i get back results and i show them in a Jlist.
what i want is that i want to show tweets nicely in the list, not only as a text .. show the image of the user, the tweet, tweeted by ... etc all this information .. in addition attach additional data like star rating .. how can i add that to a JList ? can the Jlist hold different objects .. Jpanels for example ..

Instead I suggest you put a set of JPanels inside a JScrollPane.

A JList's renderer must be a JComponent, so you can use any Swing object, including JPanels.
You can also use HTML in a JLabel if it is easier to do so than using a JPanel.
To use a custom renderer, you do something like this..
myList.setCellRenderer(new CustomRenderer());
and then create a renderer like this
public class CustomRenderer extends DefaultListCellRenderer {
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean hasFocus) {
JPanel panel = new JPanel();
// set up the panel for your exact display requirements.
return(panel);
}
}

Suggest using a JTable, which has several columns, instead of a JList.
Also suggest using GlazedLists, which makes it really easy to display lists with fields in a JTable, so that they update automatically when the underlying list changes.
Here's an example of some code I wrote recently which displays something similar:
private void bindEmailTargetTable(NotificationModel newModel) {
JTable table = getUI(UIKey.EMAIL_TARGET_TABLE);
EventList<EmailTarget> displayList = newModel.getEmailTargets();
TableFormat<EmailTarget> tf = new TableFormat<EmailTarget>()
{
#Override public int getColumnCount() {
return 4;
}
private final String[] columns = { "address", "description", "msg left", "msg limit" };
#Override public String getColumnName(int col) {
return this.columns[col];
}
#Override public Object getColumnValue(EmailTarget item, int col) {
switch (col)
{
case 0:
return item.getAddress();
case 1:
return item.getDescription();
case 2:
return item.getRemainingMessages();
case 3:
return item.getMessageLimit();
default:
return "";
}
}
};
EventTableModel<EmailTarget> etm = new EventTableModel<EmailTarget>(displayList, tf);
table.setModel(etm);
}
That's 33 lines of code to take a JTable and make it automatically update itself to display 4 fields of each EmailTarget in an EventList<EmailTarget>.
For non-text field contents, you just need a custom TableCellRenderer.

AS Jason suggested its better to go for jtable instead of JLIst. In fact you can use any free Java based table classes that have extended functionality over JTables. JIDE is one such library but its commercial. you can search and find a lot..

CheckboxCellEditor shows text and not a check box

I'm using the following
org.eclipse.jface.viewers.CheckboxCellEditor.CheckboxCellEditor(Composite parent)
I'm creating a table viewer with cellEditors and doing the following
CellEditor[] editors = new CellEditor[columnNames.length];
editors[7] = new CheckboxCellEditor(table);
I have a CellModifier that has the following
public Object getValue(Object element, String property) {
Object result = null;
...
result = Boolean.valueOf(task.isDfRequested());
return result;
}
public void modify(Object element, String property, Object value) {
item.isSelected(((Boolean)value).booleanValue());
}
Finally I have a LabelProvider that has the following
public String getColumnText(Object element, int columnIndex) {
String result = "";
try {
result = Boolean.toString(item.isSelected());
} catch (Exception ex) { }
break;
However, in my UI instead of having a check box I have the word true or false && clicking it results in switching state to false or true. Any ideas on why I don't have a checkbox??

I've searched in the source code of CheckboxCellEditor class and in the constructor the control associated to the CellEditor is created in the createControl(Composite parent) method. This method is abstract in CellEditor class and it's implemented like this in CheckboxCellEditor:
protected Control createControl(Composite parent) {
return null;
}
So a control is not created, that's why you don't see the checkbox. In the documentation of the Class you can read:
Note that this implementation simply
fakes it and does does not create any
new controls. The mere activation of
this editor means that the value of
the check box is being toggled by the
end users; the listener method
applyEditorValue is immediately called
to signal the change.
I solved this using a ComboBoxCellEditor with yes and no items.
Regards.

Well, I have no idea how SWT works or what component you are even talking about.
But I do know that when using Swing you can have custom editors for a column in a JTable. If you don't tell the table the class of data for the column then the toString() method of the data is invoked. But if you tell the table that Boolean data is displayed in the column then the table will use the check box editor.
Sounds like a similiar symptom, but I don't know your particular solution.

What I've decided to do is to just implement a dirty hack others have been using.
Create two images of check boxes, one checked the other not checked. Switch the state between the two based on the boolean.
It's not perfect, but for now it gets the job done