Adding a remove button to a column in a table

Question

Is it possible to add a Remove button to a cell in a table?

I have a table with 5 columns, I would like to add a 6th column. I want the 6th column to have

Answer 1

In addition to the answer from @sambi.reddy there is a comment that says - "make sure you dispose these buttons when viewer input changes". This is what I had to do to get that part working.

The framework I used had an implementation of IStructuredContentProvider, so in the overridden inputChanged(...), i had to put in the following code:-

@Override
public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {

    // This will dispose of all the control button that were created previously
    if (((TableViewer)viewer).getTable() != null && ((TableViewer)viewer).getTable().getChildren() != null) {
        for (Control item : ((TableViewer)viewer).getTable().getChildren()) {
            // at this point there are no other controls embedded in the viewer, however different instances may require more checking of the controls here.
            if ((item != null) && (!item.isDisposed())) {  
                item.dispose();
            }
        }
    }
}

This works fine, except if you have a refresh table (ie. viewer.setInput(List)) call as the result of you button action. When I added this the following line sometimes returned buttons that still existed, but were being disposed:

if(buttons.containsKey(cell.getElement()))

So I needed to update this line to be:

if (buttons.containsKey(cell.getElement()) && !buttons.get(cell.getElement()).isDisposed())

Which resulted in any disposing buttons being recreated, if they were still required.

Answer 2

Below code should work for you

TableItem item = (TableItem) item;
Button button = new Button(table,swt.none);
button.setText("Remove");
control.setBackground(item.getBackground());
TableEditor editor = new TableEditor(table);
editor.grabHorizontal  = true;
editor.grabVertical = true;
editor.setEditor(button , item, columnIndex);
editor.layout();

Answer 3

One important thing to the chosen answer is that you should not create an instance of TableEditor on every update method call it will slow down the performance or even make the application unresposnive.

@Override
        public void update(ViewerCell cell) {

            TableItem item = (TableItem) cell.getItem();
            Button button;
            if(buttons.containsKey(cell.getElement()))
            {
                button = buttons.get(cell.getElement());
            }
            else
            {
                button = new Button((Composite) cell.getViewerRow().getControl(),SWT.NONE);
                button.setText("Remove");
                buttons.put(cell.getElement(), button);
                TableEditor editor = new TableEditor(item.getParent());
                editor.grabHorizontal  = true;
                editor.grabVertical = true;
                editor.setEditor(button , item, cell.getColumnIndex());
                editor.layout();
            }
        }

Answer 4

Here is sample working version.

public class TableEditorTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Display display = new Display();
        Shell shell = new Shell(display);

        shell.setLayout(new FillLayout());


        TableViewer viewer = new TableViewer(shell);
        viewer.getTable().setHeaderVisible(true);
        viewer.getTable().setLinesVisible(true);
        viewer.setContentProvider(new ArrayContentProvider());

        TableColumn column = new TableColumn(viewer.getTable(), SWT.NONE);
        column.setText("First Name");
        column.setWidth(100);
        TableViewerColumn firstNameCol = new TableViewerColumn(viewer, column);
        firstNameCol.setLabelProvider(new ColumnLabelProvider(){

            @Override
            public String getText(Object element) {
                Person p = (Person)element;

                return p.getFirstName();
            }

        });

        column = new TableColumn(viewer.getTable(), SWT.NONE);
        column.setText("Last Name");
        column.setWidth(100);
        TableViewerColumn lastNameCol = new TableViewerColumn(viewer, column);
        lastNameCol.setLabelProvider(new ColumnLabelProvider(){

            @Override
            public String getText(Object element) {
                Person p = (Person)element;

                return p.getLastName();
            }

        });




        column = new TableColumn(viewer.getTable(), SWT.NONE);
        column.setText("Actions");
        column.setWidth(100);
        TableViewerColumn actionsNameCol = new TableViewerColumn(viewer, column);
        actionsNameCol.setLabelProvider(new ColumnLabelProvider(){
            //make sure you dispose these buttons when viewer input changes
            Map<Object, Button> buttons = new HashMap<Object, Button>();


            @Override
            public void update(ViewerCell cell) {

                TableItem item = (TableItem) cell.getItem();
                Button button;
                if(buttons.containsKey(cell.getElement()))
                {
                    button = buttons.get(cell.getElement());
                }
                else
                {
                     button = new Button((Composite) cell.getViewerRow().getControl(),SWT.NONE);
                    button.setText("Remove");
                    buttons.put(cell.getElement(), button);
                }
                TableEditor editor = new TableEditor(item.getParent());
                editor.grabHorizontal  = true;
                editor.grabVertical = true;
                editor.setEditor(button , item, cell.getColumnIndex());
                editor.layout();
            }

        });



        Person p1 = new Person();
        p1.setFirstName("George");
        p1.setLastName("Burne");

        Person p2 = new Person();
        p2.setFirstName("Adam");
        p2.setLastName("Silva");

        Person p3 = new Person();
        p3.setFirstName("Nathan");
        p3.setLastName("Cowl");

        List<Person> persons = new ArrayList<Person>();
        persons.add(p1);
        persons.add(p2);
        persons.add(p3);

        viewer.setInput(persons);

        shell.open();
        while(!shell.isDisposed())
        {

            if(!display.readAndDispatch())
            {
                display.sleep();
            }
        }

        display.dispose();

    }


    private static class Person
    {

        String firstName;
        String lastName;

        Person()
        {

        }

        public String getFirstName() {
            return firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }

    }


}