Eclipse JFace/SWT ViewerFilter select never gets called - eclipse

Question

I'm trying to build a simple dialog with a TableViewer in it, along with a checkbox which would filter the data. However the table is empty and the filtering never gets done. Whats wrong with this code?
public class AsTestDialog extends TitleAreaDialog {
private Table table;
private AsTestFilter filter;
private TableViewer tableViewer;
public AsTestDialog(Shell parentShell) {
super(parentShell);
}
#Override
public void create() {
super.create();
setTitle("Table Test");
}
#Override
protected Control createDialogArea(Composite parent) {
Composite area = (Composite) super.createDialogArea(parent);
area.setLayout(new GridLayout(1, false));
tableViewer = new TableViewer(area, SWT.BORDER | SWT.FULL_SELECTION);
table = tableViewer.getTable();
table.setHeaderVisible(true);
table.setLinesVisible(true);
table.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true, 1, 1));
TableViewerColumn tableViewerColumn = new TableViewerColumn(tableViewer, SWT.NONE);
TableColumn tblclmnNewColumn = tableViewerColumn.getColumn();
tblclmnNewColumn.setWidth(130);
tblclmnNewColumn.setText("Column1");
TableViewerColumn tableViewerColumn_2 = new TableViewerColumn(tableViewer, SWT.NONE);
TableColumn tblclmnId = tableViewerColumn_2.getColumn();
tblclmnId.setWidth(150);
tblclmnId.setText("Column2");
Composite composite = new Composite(area, SWT.NONE);
composite.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, false, false, 1, 1));
Button btnFilter = new Button(composite, SWT.CHECK);
btnFilter.setBounds(10, 10, 111, 20);
btnFilter.setText("Filter");
btnFilter.addSelectionListener(new SelectionListener() {
#Override
public void widgetSelected(SelectionEvent e) {
System.out.println("CHECKBOX SELECTED");
filter.setFilterType("foobar");
tableViewer.refresh();
}
#Override
public void widgetDefaultSelected(SelectionEvent e) {}
});
addTestData(table);
//Filter
filter = new AsTestFilter();
tableViewer.addFilter(filter);
tableViewer.getTable().pack();
tableViewer.refresh();
return area;
}
private void addTestData(Table table) {
TableItem item1 = new TableItem(table, SWT.NONE);
item1.setText(new String[] {"1","2"});
item1.setData("1");
TableItem item2 = new TableItem(table, SWT.NONE);
item2.setText(new String[] {"3","4"});
item2.setData("3");
}
}
The filter class:
public class AsTestFilter extends ViewerFilter {
private String filterType = "all";
public void setFilterType(String tp) {
this.filterType = tp;
}
#Override
public boolean select(Viewer viewer, Object parentElement, Object element) {
System.out.println("SELECT CALLED: "+filterType);
return true;
}
}

Answer 1

If you are using the JFace TableViewer you must use a 'content provider' set with
tableViewer.setContentProvider(provider);
and then call
tableViewer.setInput(input data);
creating TableItem objects directly will not work properly as TableViewer expects to create these objects itself.
If you have a simple array or List of objects the content provider can simply be:
tableViewer.setContentProvider(ArrayContentProvider.getInstance());
and the set input:
tableViewer.setInput(array or list);
Your filter is not called because you have not called setInput, the table viewer does nothing until this is called.

Answer 2

The ViewerFilter operates on the TableViewer's input, which will be null in your case as you aren't using tableViewer.setInput(model). Instead you are creating TableItems directly.
You will need to set up a content provider, label provider, and define a model which you can pass to .setInput for the table viewer, and remove the function which directly creates the TableItems.
Once you do this, the ViewerFilter should work.
There are plenty of tutorials around which describe this, including https://eclipse.org/articles/Article-Table-viewer/table_viewer.html and http://wiki.eclipse.org/index.php/JFaceSnippets