Develop Reference

SWT - Table Viewer center checkbox

The last column of my Table Viewer contains a check box only. The check box appears in the left side of the cell, and because the column name is pretty long it looks ugly as hell. How can I center the check box in the middle of the cell ? Is it possible without using images ? Here is how I create the column:
// third column - check box. temporary
TableColumn column = new TableColumn(viewer.getTable(), SWT.NONE);
column.setText("PrettyLongColumnName");
column.setWidth(100);
TableViewerColumn checkColumn = new TableViewerColumn(viewer, column);
checkColumn.setLabelProvider(new ColumnLabelProvider() {
// the checkboxes should be disposed and rebuilt when input changes
#Override
public void update(ViewerCell cell) {
MyObject system = (MyObject) cell.getElement();
TableItem item = (TableItem) cell.getItem();
Button button;
if (buttonsMap.containsKey(cell.getElement())) {
button = rightTableButtons.get(cell.getElement());
} else {
button = new Button((Composite) cell.getViewerRow().getControl(), SWT.CHECK);
button.setEnabled(true);
buttonsMap.put(cell.getElement(), button);
TableEditor editor = new TableEditor(item.getParent());
editor.grabHorizontal = true;
editor.grabVertical = true;
editor.setEditor(button, item, cell.getColumnIndex());
editor.layout();
}
}
}
});

TL;DR: Not available nativley, but can be implemented via epic hackery.
Checkboxes are actually an OS feature. As SWT is cross-platform, we rely on it being provided by OS.
AFIK the only thing provided by all OS's (Gtk/Win32/Cocoa) is a single checkbox on the first column.
Other
fancy functionality has to be implemented manually.
One way I've seen people do it is to draw custom icons and then update the icon when you click on it with event listeners.
One example on how to draw icons on the right is in this snippet. You'd have to add click listener to change the icon when clicked into checked/unchecked.
Note, this may cause your application to look inconsistent across platforms and themes (e.g dark theme).
To get around this, we have had some people that actually generate a native checkbox, then programatically take a screen shot, then draw it in the right side of a column. I think this is hackery at it's finest.
Let me know if you have questions.

When combo box is selected then display Combo Box and then when any Item in Combo Box is selected then make JTextField visible

I am having trouble with my code. What i'm trying to do is:
1. Create a Check Box, make it visible
2. When Check Box is selected display Combo Box, which will have few items for example ("1","2")
3. When 1 is selected from Combo Box then make 1 Text Field visible
4. When 2 is selected from Combo Box then make 2 Text Field's visible
What I am able to do is when Check Box is clicked, it displays the Combo Box with the items.
I am not able provide functionality to the items in the Combo Box, such as when Item1 is clicked then make 1 Text Field visible.
Please help needed.
My Code:
public void replacement_used(){
no_of_part_used_label.setVisible(false);
no_part_used_list.setVisible(false);
part_no_one_label.setVisible(false);
part_no_one_field.setVisible(false);
part_no_two_label.setVisible(false);
part_no_two_field.setVisible(false);
part_no_three_label.setVisible(false);
part_no_three_field.setVisible(false);
part_no_four_label.setVisible(false);
part_no_four_field.setVisible(false);
part_no_five_label.setVisible(false);
part_no_five_field.setVisible(false);
HandlerClass handler = new HandlerClass();
replacement_part_check_box.addItemListener(handler);
}
private class HandlerClass implements ItemListener{
public void itemStateChanged(ItemEvent event){
if (replacement_part_check_box.isSelected()){
no_of_part_used_label.setVisible(true);
no_part_used_list.setVisible(true);
}
x();
}
}
public void x(){
System.out.println("Start of x fucntion");
if( no_part_used_list.getSelectedItem().equals("1") ){
System.out.println("It is 1");
part_no_one_label.setVisible(true);
part_no_one_field.setVisible(true);
}
}

Well All you need to do is to add an ActionListener to your ComboBox.
May be first you should go through this link so that you can understand the basics of using combobox in swing http://docs.oracle.com/javase/tutorial/uiswing/components/combobox.html
Also you need to learn coding conventions so that your code could become more readable and understandable.

Remove column from column control popup menu

Is it possible to control whether a column should be available in a column control popup menu? I'm aware of toggling (Disable/enable using CheckBoxList) and gray-out the column. But I do not want column entry in popup menu as The column is must-have column in Jtable. I'm using the JXTable. Anyone that have any hints?

A TableColumnExt has a property hideable which effectly disables the hiding. It is still shown in the popup and you can toggle the checkbox (that's a bug, just filed - the menu item should be disabled ;), but at least the column isn't hidden. To work around the bug, you can implement a custom column control (as Robin correctly suggested) which doesn't add the checkbox, something like:
JXTable table = new JXTable(new AncientSwingTeam());
// here the hideable property is configured manually,
// in production code you'll probably have a custom ColumnFactory
// doing it based on some data state
table.getColumnExt(0).setHideable(false);
ColumnControlButton columnControl = new ColumnControlButton(table) {
#Override
protected ColumnVisibilityAction createColumnVisibilityAction(
TableColumn column) {
if (column instanceof TableColumnExt
&& !((TableColumnExt) column).isHideable())
return null;
return super.createColumnVisibilityAction(column);
}
};
table.setColumnControl(columnControl);
table.setColumnControlVisible(true);
As to not including the menu item: when introducing the hideable property, we decided to go for keeping the item in the list but disable it because users might get confused not seeing all columns in the control. So once the bug will be fixed (just done, committed as of revision #4315), I would recommend to remove the custom column control again. Just my 2 euro-cents, though :-)

ColumnControlButton#createColumnVisibilityAction looks like the method you are looking for. According to the documentation:
Creates and returns a ColumnVisibilityAction for the given TableColumn. The return value might be null, f.i. if the column should not be allowed to be toggled
you can return null for your case.
You should be able to plug this in by using the JXTable#setColumnControl method.

First way:
myTable().getColumnExt(_column_number_).setHideable(false);
This works smooth but has one UI drawback: text in menu is gray and thick is black - bad user experience.
So try to fix it, text will be gray and thick won't be here:
public class MyTable extends JXTable
{
public MyTable(AbstractTableModel model)
{
//first two columns won't be hiddeable
ColumnControlButton controlButton = new ColumnControlButton(this)
{
#Override
protected ColumnControlPopup createColumnControlPopup()
{
return (new NFColumnControlPopup());
}
class NFColumnControlPopup extends DefaultColumnControlPopup
{
#Override
public void addVisibilityActionItems(List<? extends AbstractActionExt> actions)
{
for(int i = 0; i < actions.size(); i++)
{
AbstractActionExt action = actions.get(i);
JCheckBoxMenuItem chk = new JCheckBoxMenuItem(action);
//Disabling unwanted items but they will be still shown for smooth user experience
if(i == 0 || i == 1)
{
chk.setEnabled(false);
chk.setSelected(false);
//chk.setIcon(new ImageIcon(Icons.class.getResource("check.png")));
}
else
{
chk.setSelected(true);
}
chk.addItemListener(action);
super.addItem(chk);
}
}
}
};
this.setColumnControl(controlButton);
}
}
and if you need to hide controls for "show horizontal scrollbar", "pack" and "pack all" add into code:
//remove items for horizontal scrollbar, pack and packall
this.getActionMap().remove("column.horizontalScroll");
this.getActionMap().remove("column.packAll");
this.getActionMap().remove("column.packSelected");
right after calling super(model)

display results from a combo box in swt

I have a combo box with a list of entries and when I choose an entry eg dog I want to display an image of a dog beside the combo box.
Would anybody have any examples of this in swt that I could take a look at?
Ann.

Add a SelectionListener to your combo box.
combo.addSelectionListener( new SelectionAdapter() {
public void widgetSelected( SelectionEvent event ) {
// ...
}
} );
On the widgetSelectedmethod, get the selection index - using combo.getSelectionIndex() -, map it to your image and display it wherever you want (e.g. on a Label: label.setImage(image)).

How to get a handle to all JCheckBox objects in order to loop?

I'm very new to Java and am having some issues looping through JCheckBoxes on a UI. The idea is that I have a bunch of checkboxes (not in a group because more than one can be selected.) When I click a JButton, I want to build a string containing the text from each selected checkbox. The issue I'm having is that our instructor told us that the checkboxes need to be created via a method, which means (see code below) that there isn't a discrete instance name for each checkbox. If there were, I could say something like
if(checkBox1.isSelected()) {
myString.append(checkBox.getText());
}
That would repeat for checkBox2, checkBox3, and so on. But the method provided to us for adding checkboxes to a panel looks like this:
public class CheckBoxPanel extends JPanel {
private static final long serialVersionUID = 1L;
public CheckBoxPanel(String title, String... options) {
setBorder(BorderFactory.createTitledBorder(BorderFactory
.createEtchedBorder(), title));
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
// make one checkbox for each option
for (String option : options) {
JCheckBox b = new JCheckBox(option);
b.setActionCommand(option);
add(b);
}
}
}
This is called like this:
toppingPanel = new CheckBoxPanel("Each Topping $1.50", "Tomato", "Green Pepper",
"Black Olives", "Mushrooms", "Extra Cheese",
"Pepperoni", "Sausage");
So I now have a panel that contains a border with the title "Each Topping $1.50", and 7 visible checkboxes. What I need to do is get a list of all the selected toppings. We are not supposed to use an ActionListener for each checkbox, but rather get the list when a button is clicked. I'm feeling really clueless here, but I just can't figure out how to get the isSelected property of the checkboxes when the individual checkboxes don't have instance names.
Ideally I'd like to somehow add all the checkboxes to an array and loop through the array in the button's action listener to determine which ones are checked, but if I have to check each one individually I will. I just can't figure out how to refer to an individual checkbox when they've been created dynamically.

I'm assuming you're not allowed to alter the CheckBoxPanel code at all. Which seems like a useless exercise, because in the real world, you'd think that if CheckBoxPanel where a class being provided to you (e.g. in a library) it would include a way of getting the selected options. Anyway, due to the limitation, you could do something like this:
for( int i=0; i<checkBoxPanel.getComponentCount(); i++ ) {
JCheckBox checkBox = (JCheckBox)checkBoxPanel.getComponent( i );
if( checkBox.isSelected() ) {
String option = checkBox.getText();
// append text, etc
}
}

I suggest you maintain a list of checkboxes:
List<JCheckBox> checkboxes = new ArrayList<JCheckBox>();
and before add(b) do:
checkboxes.add(b);
You may then iterate through the list of checkboxes in the buttons action-code using a "for-each" loop construct:
for (JCheckBox cb : checkboxes)
if (cb.isSelected())
process(cb.getText()); // or whatever.
Alternatively, if you need to keep track of the specific index:
for (int i = 0; i < checkboxes.size(); i++)
if (checkboxes.get(i).isSelected())
....

I would suggest that you dont put each of the checkboxes in a List when you create them. Instead, in your shared ActionListener, you maintain a Set of all selected checkboxes. Use the getSource method on the ActionEvent to identify which checkbox the user selected and then cast it to a JCheckBox. If isSelected() returns true for the item in question, attempt to add it to your selectedItems Set. If it is not, then attempt to remove it.
You can then just iterate over the subset of all items (only those that are selected) and print them to the console.