Demonstrate a Map Implemented with ArrayLists

package com.bruceeckel;
 
//: c11:SlowMap.java
//A Map implemented with ArrayLists.
//From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
//www.BruceEckel.com. See copyright notice in CopyRight.txt.
 
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
 
public class SlowMap extends AbstractMap {
 
    private List keys = new ArrayList(), values = new ArrayList();
 
    public Object put(Object key, Object value) {
	Object result = get(key);
	if (!keys.contains(key)) {
	    keys.add(key);
	    values.add(value);
	} else
	    values.set(keys.indexOf(key), value);
	return result;
    }
 
    public Object get(Object key) {
	if (!keys.contains(key))
	    return null;
	return values.get(keys.indexOf(key));
    }
 
    public Set entrySet() {
	Set entries = new HashSet();
	Iterator ki = keys.iterator(), vi = values.iterator();
	while (ki.hasNext())
	    entries.add(new MPair(ki.next(), vi.next()));
	return entries;
    }
 
    public String toString() {
	StringBuffer s = new StringBuffer("{");
	Iterator ki = keys.iterator(), vi = values.iterator();
	while (ki.hasNext()) {
	    s.append(ki.next() + "=" + vi.next());
	    if (ki.hasNext())
		s.append(", ");
	}
	s.append("}");
	return s.toString();
    }
 
    public static void main(String[] args) {
	SlowMap m = new SlowMap();
	m.put("Adobe", "Mountain View, CA");
	m.put("IBM", "White Plains, NY");
	m.put("Learning Tree", "Los Angeles, CA");
	m.put("Microsoft", "Redmond, WA");
	m.put("Netscape", "Mountain View, CA");
	m.put("O'Reilly", "Sebastopol, CA");
	m.put("Sun", "Mountain View, CA");
	System.out.println(m);
 
    }
} // /:~
 
class MPair implements Entry, Comparable {
    Object key, value;
 
    MPair(Object k, Object v) {
	key = k;
	value = v;
    }
 
    public Object getKey() {
	return key;
    }
 
    public Object getValue() {
	return value;
    }
 
    public Object setValue(Object v) {
	Object result = value;
	value = v;
	return result;
    }
 
    public boolean equals(Object o) {
	return key.equals(((MPair) o).key);
    }
 
    public int compareTo(Object rv) {
	return ((Comparable) key).compareTo(((MPair) rv).key);
    }
}