assertion failed: Unknown column layout data - swt

Question

When I create combo box in particular only one 3rd column using table viewer in Eclipse SWT.
I think I've done everything ok until now, however when I compile the code then i get error:
Code:
public void createPartControl(Composite parent) {
Composite tableComposite = new Composite(parent, SWT.NONE);
tableColumnLayout = new TableColumnLayout();
tableComposite.setLayout(tableColumnLayout);
tableComposite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true,
true));
tableViewer = new TableViewer(tableComposite, SWT.MULTI | SWT.H_SCROLL
| SWT.V_SCROLL);
tableViewer.setContentProvider(ArrayContentProvider.getInstance());
// TODO viewer.setLabelProvider(new ViewLabelProvider());
table = tableViewer.getTable();
// Table table = tableViewer.getTable();
table.setHeaderVisible(true);
table.setLinesVisible(true);
String[] titles = { "Threat Name", "Category Name", "Status",
"Priority", "Description", "Justification" };
int[] bounds = { 100, 100, 100, 100 };
TableViewerColumn col = createTableViewerColumn(titles[2], bounds[2], 2);
col.setLabelProvider(new ColumnLabelProvider() {
#Override
public String getText(Object element) {
Dummy p = (Dummy) element;
return p.getValue();
}
});
col.setEditingSupport(new FirstValueEditingSupport(tableViewer));
}
private SelectionAdapter getSelectionAdapter(final TableColumn column,
final int index) {
SelectionAdapter selectionAdapter = new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent e) {
tableViewer.refresh();
}
};
return selectionAdapter;
}
private static class Dummy {
public String value;
public Dummy(String value) {
this.value = value;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
public static class FirstValueEditingSupport extends EditingSupport {
private final TableViewer viewer;
private final CellEditor editor;
private final String[] possibleValues = { "Mitigated",
"Not Applicable", "Not Started", "Needs Investigation" };
public FirstValueEditingSupport(TableViewer viewer) {
super(viewer);
this.viewer = viewer;
this.editor = new ComboBoxCellEditor(viewer.getTable(),
possibleValues);
}
#Override
protected CellEditor getCellEditor(Object element) {
return editor;
}
#Override
protected boolean canEdit(Object element) {
return true;
}
#Override
protected Object getValue(Object element) {
Dummy dummy = (Dummy) element;
int index = 0;
for (int i = 0; i < possibleValues.length; i++) {
if (Objects.equals(possibleValues[i], dummy.getValue())) {
index = i;
break;
}
}
return index;
}
#Override
protected void setValue(Object element, Object value) {
Dummy dummy = (Dummy) element;
int index = (Integer) value;
dummy.setValue(possibleValues[index]);
viewer.update(element, null);
}
}
private void fillRows(String shortdesc, String categ, String descp) {
System.out.println("fillRows call from above method.");
TableColumn status_Name_Col = tableViewer.getTable().getColumn(2);
System.out.println("**************** status_Name_Col ************ "
+ status_Name_Col);
tableViewer
.addSelectionChangedListener(new ISelectionChangedListener() {
#Override
public void selectionChanged(
SelectionChangedEvent selectionChangedEvent) {
StructuredSelection selection = (StructuredSelection) selectionChangedEvent
.getSelection();
System.out.println(((Dummy) selection.getFirstElement())
.getValue());
}
});
List<Dummy> elements = new ArrayList<>();
for (int i = 0; i < Connection.Number_Of_Connection; i++) {
elements.add(new Dummy("First option"));
}
tableViewer.setInput(elements);
tableColumnLayout.setColumnData(status_Name_Col, new ColumnWeightData(
1, true));
tableViewerColumn.setEditingSupport(new FirstValueEditingSupport(
tableViewer));
}
Questions:
how to display combo box in particular only one column?

Answer 1

You must not do the TableViewer setInput call until you have set up everything on the table. All the content providers, label providers, column layouts, editing support, .... must be set before setInput is called.
You must also call setColumnData for every column you create.