public void resort() {
    viewer.setComparator(null);
    viewer.setComparator(this);
}

    viewer.setComparator(this);

public final static String SORTER_PROPERTY = "sorterProperty";

tableViewer.setComparator(new ViewerSorter() {
    @Override
    public int compare(Viewer viewer, Object e1, Object e2) {
        [...]
    }
    
    @Override
    public boolean isSorterProperty(Object element, String property) {
        return SORTER_PROPERTY.equals(property);
    }
});

// Update a specific element and trigger re-sorting.
tableViewer.update(element, new String[] { SORTER_PROPERTY });

// Same thing but without re-sorting.
tableViewer.update(element, null);