// ListApplet.java

import  java.applet.*;
import  java.awt.*;
import  java.util.*;

public
    class       ListApplet
    extends     Applet
    implements  Observer
    {
    static final String oStringChangedName = "changedName".intern();

    private ObjectApplet    oObjectApplet;
    private List            oList;
    private Vector          oVector;

//  CONSTRUCTORS

    public
        ListApplet
        (
        ObjectApplet    poObjectApplet
        )
        {
        init(poObjectApplet);
        }

//  PUBLIC METHODS

    public
        Vector      getVector
        (
        )
        {
        return oVector;
        }

    public
        boolean     handleEvent
        (
        Event       poEvent
        )
        {
        int i;
        if (poEvent.target == oList)
            {
            if (Event.LIST_SELECT == poEvent.id)
                {
                i = ((Integer)poEvent.arg).intValue();
                setObject(getVector().elementAt(i));
                }
            else if (Event.LIST_DESELECT == poEvent.id)
                oObjectApplet.setObject(null);
            }
        return super.handleEvent(poEvent);
        }

    public
        void        init
        (
        ObjectApplet    poObjectApplet
        )
        {
        super.init();
        setLayout(new GridLayout(1,2,5,5));
        oList           = new List();
        oObjectApplet   = poObjectApplet;
        add(oList);
        add(oObjectApplet);
        setObject(null);
        }

    public
        void        setVector
        (
        Vector      poVector
        )
        throws NoSuchElementException
        {
        oObjectApplet.clear();
        oList.clear();
        oVector = poVector;
        for (Enumeration e = poVector.elements(); e.hasMoreElements(); )
            oList.addItem(e.nextElement().toString());
        }

    public
        void        update
        (
        Observable  poObservable,
        Object      poObject
        )
        {
        String      oString;
        if (oStringChangedName == poObject)
            {
            int i = getVector().indexOf(poObservable);
            oString = ((NamedObject)poObservable).getName().toString();
            oList.replaceItem(oString,i);
            oList.select(i);
            }
        }

//  PROTECTED METHODS

    protected
        void    addElement
        (
        Object  poObject
        )
        {
        int     i;

        getVector().addElement(poObject);
        i = oList.getItemCount();
        oList.addItem(poObject.toString());
        oList.makeVisible(i);
        oList.select(i);
        setObject(poObject);
        }

    protected
        void    removeElementAt
        (
        int     pi
        )
        {
        getVector().removeElementAt(pi);
        oList.delItem(pi);
        setObject(null);
        }
 
    protected
        void    setObject
        (
        Object  poObject
        )
        {
        Observable oObjectNew = (Observable)poObject;
        Observable oObjectOld = (Observable) oObjectApplet.getObject();
        if (null != oObjectOld) oObjectOld.deleteObserver   (this);
        if (null != oObjectNew) oObjectNew.addObserver      (this);
        oObjectApplet.setObject(oObjectNew);
        }
    }