JFace also supports sorting the data in its viewers. You can use the method setComparator() on the viewer object. This method expects an object of type "ViewerComparator". "ViewerComparator" can be extended, per default it will sort based on the toString() method of the object in the viewer.

In our example we will allow to sort based on different columns, therefore our ViewerComparator will have the option to set the sort column.

Create a new Class "de.vogella.jface.tableviewer.sorter.MyViewerComparator.java"

			
package de.vogella.jface.tableviewer.sorter;

import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerComparator;

import de.vogella.jface.tableviewer.model.Person;

public class MyViewerComparator extends ViewerComparator {
	private int propertyIndex;
	private static final int DESCENDING = 1;
	private int direction = DESCENDING;

	public MyViewerComparator() {
		this.propertyIndex = 0;
		direction = DESCENDING;
	}

	public void setColumn(int column) {
		if (column == this.propertyIndex) {
			// Same column as last sort; toggle the direction
			direction = 1 - direction;
		} else {
			// New column; do an ascending sort
			this.propertyIndex = column;
			direction = DESCENDING;
		}
	}

	@Override
	public int compare(Viewer viewer, Object e1, Object e2) {
		Person p1 = (Person) e1;
		Person p2 = (Person) e2;
		int rc = 0;
		switch (propertyIndex) {
		case 0:
			rc = p1.getFirstName().compareTo(p2.getFirstName());
			break;
		case 1:
			rc = p1.getLastName().compareTo(p2.getLastName());
			break;
		case 2:
			rc = p1.getGender().compareTo(p2.getGender());
			break;
		case 3:
			if (p1.isMarried() == p2.isMarried()) {
				rc = 0;
			} else
				rc = (p1.isMarried() ? 1 : -1);
			break;
		default:
			rc = 0;
		}
		// If descending order, flip the direction
		if (direction == DESCENDING) {
			rc = -rc;
		}
		return rc;
	}

}

		

In "View" change the method "createTableViewerColumn" and create a new method "getSelectionAdapter()". This method will add a listener to the columns. If one of the columns is selected the sorting column in ViewerComparator will be set.

				private MyViewerComparator comparator;

	public void createPartControl(Composite parent) {
		GridLayout layout = new GridLayout(2, false);
		parent.setLayout(layout);
		Label searchLabel = new Label(parent, SWT.NONE);
		searchLabel.setText("Search: ");
		searchText = new Text(parent, SWT.BORDER | SWT.SEARCH);
		searchText.setLayoutData(new GridData(GridData.GRAB_HORIZONTAL
				| GridData.HORIZONTAL_ALIGN_FILL));
		searchText.addKeyListener(new KeyAdapter() {
			public void keyReleased(KeyEvent ke) {
				filter.setSearchText(searchText.getText());
				viewer.refresh();
			}

		});

		createViewer(parent);
		comparator = new MyViewerComparator();
		viewer.setComparator(comparator);

	}



private TableViewerColumn createTableViewerColumn(String title, int bound,
			final int colNumber) {
		final TableViewerColumn viewerColumn = new TableViewerColumn(viewer,
				SWT.NONE);
		final TableColumn column = viewerColumn.getColumn();
		column.setText(title);
		column.setWidth(bound);
		column.setResizable(true);
		column.setMoveable(true);
		column.addSelectionListener(getSelectionAdapter(column, colNumber));
		return viewerColumn;

	}

	private SelectionAdapter getSelectionAdapter(final TableColumn column,
			final int index) {
		SelectionAdapter selectionAdapter = new SelectionAdapter() {
			@Override
			public void widgetSelected(SelectionEvent e) {
				comparator.setColumn(index);
				int dir = viewer.getTable().getSortDirection();
				if (viewer.getTable().getSortColumn() == column) {
					dir = dir == SWT.UP ? SWT.DOWN : SWT.UP;
				} else {

					dir = SWT.DOWN;
				}
				viewer.getTable().setSortDirection(dir);
				viewer.getTable().setSortColumn(column);
				viewer.refresh();
			}
		};
		return selectionAdapter;
	}

		

If you run the example and click on a column header, the table should be sorted according to the content of this column. There will also appear a sort-direction in the top of the column.