Create the following label and content provider for your JFace viewers.

			
package de.vogella.dnd.jface.viewers;

import java.util.List;

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

import de.vogella.dnd.jface.model.Todo;

public class TableContentProvider implements IStructuredContentProvider {

	@Override
	public Object[] getElements(Object inputElement) {
		List<Todo> list = (List<Todo>) inputElement;
		return list.toArray();
	}

	@Override
	public void dispose() {
		
	}

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

}

		

			
package de.vogella.dnd.jface.viewers;

import java.util.List;

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

public class TreeContentProvider implements ITreeContentProvider {

	@Override
	public Object[] getChildren(Object parentElement) {
		return null;
	}

	@Override
	public Object getParent(Object element) {
		return null;
	}

	@Override
	public boolean hasChildren(Object element) {
		return false;
	}

	@Override
	public Object[] getElements(Object inputElement) {
		List<String> list = (List<String>) inputElement;
		return list.toArray();
	}

	@Override
	public void dispose() {
		
	}

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

}

		

			
package de.vogella.dnd.jface.viewers;

import org.eclipse.jface.viewers.BaseLabelProvider;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.swt.graphics.Image;

import de.vogella.dnd.jface.model.Todo;

public class TableLabelProvider extends BaseLabelProvider implements
		ITableLabelProvider {

	@Override
	public Image getColumnImage(Object element, int columnIndex) {
		return null;
	}

	@Override
	public String getColumnText(Object element, int columnIndex) {
		Todo todo = (Todo) element;
		switch (columnIndex) {
		case 0:
			return todo.getShortDescription();
		case 1:
			return todo.getLongDescription();
		}
		return "Not supported";
	}

}

		

			
package de.vogella.dnd.jface.viewers;

import org.eclipse.jface.viewers.LabelProvider;


public class TreeLabelProvider extends LabelProvider {
	@Override
	public String getText(Object element) {
		String s = (String) element; 
		return s;
	}

}