java unchecked or unsafe operations error

I am getting the following error

Note: C:\Documents and Settings\Eugene\Desktop\client\LocalBoard.java
uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

for the code bellow:

Toobar.java
----------------

import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.awt.*;
import java.util.Vector;
import java.util.Iterator;

public class Toolbar extends JPanel implements ChangeListener{
    private WhiteboardState whiteboardState;
    private Vector toolButtons;
    public Toolbar(WhiteboardState w, LayoutManager l){
    super(l);
    whiteboardState = w;
    toolButtons = new Vector();
    }

    public Component add(Component c){
    if (c instanceof ToolButton){
        toolButtons.add(c);
    }
    return super.add(c);
    }

    public void stateChanged(ChangeEvent e){
    ToolButton changed = (ToolButton)e.getSource();
    if (changed.isSelected()){
        whiteboardState.currentTool = changed.tool;
        changed.setSelected(true);
    } else {
        whiteboardState.currentTool = null;
    }
    Iterator i = toolButtons.iterator();
    ToolButton t;
    while(i.hasNext()){
        t = (ToolButton) i.next();
        if (t != changed){
        t.setSelected(false);
        }
    }
    repaint();
    }
}

LocalBoard.java
----------------------

import java.util.*;
import java.rmi.*;

public class LocalBoard implements ShapeBuffer {

    protected Hashtable shapes; // our list of shapes
    protected int minZ = Integer.MAX_VALUE;
    protected int maxZ = Integer.MIN_VALUE;

    public LocalBoard() {
        shapes = new Hashtable();
    }

    public Updater trylock(Shape s) {
    // Unimplemented in LocalBoard
    // (don't modify this class; just write RemoteBoard)
    return null;
    }

    /** Returns read-only list of content in the canvas */
    public Collection getAllShapes() throws RemoteException {
        Enumeration e;
        Integer crKey;
        List v = new ArrayList();
        Shape shp;

        for(e = shapes.keys();e.hasMoreElements();) {
            crKey = (Integer)e.nextElement();
            shp = (Shape)shapes.get(crKey);
            v.add(shp);
        }

        // sorting by ID
        Collections.sort(v,new Comparator(){

                public int compare(Object arg0, Object arg1) {
                    Shape s1, s2;

                    s1 = (Shape)arg0;
                    s2 = (Shape)arg1;

                    return s1.getID() - s2.getID();
                }
            });

        return v;
    }

    /** Add a subscriber */
    public void attach(Subscriber o) {
    // Unimplemented in LocalBoard
    // (don't modify this class; just write RemoteBoard)
    }

    /** Remove a subscriber */
    public void detach(Subscriber o) {
    // Unimplemented in LocalBoard
    // (don't modify this class; just write RemoteBoard)
    }

    public int addShape(Shape newShape) throws InvalidShapeException,
OverflowException, RemoteException {
        int ID;
        int zIndex = newShape.getZIndex();

        if(newShape == null) throw new InvalidShapeException("Null
shape data in addShape!");
        if(getShapeCount() >= MAX_CAPACITY) throw new
OverflowException("Shape buffer overflow!");

        ID = newShape.getID();
        shapes.put(new Integer(ID),newShape);

        if(minZ > zIndex) minZ = zIndex;
        if(maxZ < zIndex) maxZ = zIndex;

        return ID;
    }

    public boolean containsShape(int ID) throws RemoteException {
        return shapes.containsKey(new Integer(ID));
    }

    public boolean isEmpty() throws RemoteException {
        return (shapes.size() == 0);
    }

    public int getShapeCount() throws RemoteException {
        return shapes.size();
    }

    public Shape getShape(int ID) throws NoSuchShapeException,
RemoteException {
        if(containsShape(ID)) return (Shape)shapes.get(new
Integer(ID));
        else throw new NoSuchShapeException("No shape with ID " + ID);
    }

    public void bringToFront(int ID) throws NoSuchShapeException,
RemoteException {
    }

    public void sendToBack(int ID) throws NoSuchShapeException,
RemoteException {
    }

    public Collection getByZIndex(int z) throws RemoteException {
        return null;
    }

    public int getMinZIndex() throws RemoteException {
        return 0;
    }

    public int getMaxZIndex() throws RemoteException {
        return 0;
    }

}

How do I solve the problem?

Your help is kindly appreciated.