ArrayMap

package example.array;
 
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
 
public class ArrayMap extends AbstractMap implements Cloneable, Serializable {
 
    static class Entry implements Map.Entry {
	protected Object key, value;
 
	public Entry(Object key, Object value) {
	    this.key = key;
	    this.value = value;
	}
 
	public Object getKey() {
	    return key;
	}
 
	public Object getValue() {
	    return value;
	}
 
	public Object setValue(Object newValue) {
	    Object oldValue = value;
	    value = newValue;
	    return oldValue;
	}
 
	public boolean equals(Object o) {
	    if (!(o instanceof Map.Entry)) {
		return false;
	    }
	    Map.Entry e = (Map.Entry) o;
	    return (key == null ? e.getKey() == null : key.equals(e.getKey()))
		    && (value == null ? e.getValue() == null : value.equals(e.getValue()));
	}
 
	public int hashCode() {
	    int keyHash = (key == null ? 0 : key.hashCode());
	    int valueHash = (value == null ? 0 : value.hashCode());
	    return keyHash ^ valueHash;
	}
 
	public String toString() {
	    return key + "=" + value;
	}
    }
 
    private Set entries = null;
 
    private ArrayList list;
 
    public ArrayMap() {
	list = new ArrayList();
    }
 
    public ArrayMap(Map map) {
	list = new ArrayList();
	putAll(map);
    }
 
    public ArrayMap(int initialCapacity) {
	list = new ArrayList(initialCapacity);
    }
 
    public Set entrySet() {
	if (entries == null) {
	    entries = new AbstractSet() {
		public void clear() {
		    list.clear();
		}
 
		public Iterator iterator() {
		    return list.iterator();
		}
 
		public int size() {
		    return list.size();
		}
	    };
	}
	return entries;
    }
 
    public Object put(Object key, Object value) {
	int size = list.size();
	Entry entry = null;
	int i;
	if (key == null) {
	    for (i = 0; i < size; i++) {
		entry = (Entry) (list.get(i));
		if (entry.getKey() == null) {
		    break;
		}
	    }
	} else {
	    for (i = 0; i < size; i++) {
		entry = (Entry) (list.get(i));
		if (key.equals(entry.getKey())) {
		    break;
		}
	    }
	}
	Object oldValue = null;
	if (i < size) {
	    oldValue = entry.getValue();
	    entry.setValue(value);
	} else {
	    list.add(new Entry(key, value));
	}
	return oldValue;
    }
 
    public Object clone() {
	return new ArrayMap(this);
    }
 
    public static void main(String args[]) {
	Map map = new ArrayMap(13);
	map.put("1", "One");
	map.put("2", "Two");
	map.put("3", "Three");
	map.put("4", "Four");
	map.put("5", "Five");
	map.put("6", "Six");
	map.put("7", "Seven");
	map.put("8", "Eight");
	map.put("9", "Nine");
	map.put("10", "Ten");
	map.put("11", "Eleven");
	map.put("12", "Twelve");
	map.put("13", "Thirteen");
	System.out.println(map);
	System.out.println(map.keySet());
	System.out.println(map.values());
    }
}