multimap.java

基于Java的软件信息系统－项目管理

package db;

import java.util.*;
import java.util.Map;
import java.util.Collection;
import java.util.Set;

public class MultiMap implements Map
{
    private Map m_map;

    public MultiMap ()
    {
	m_map = new HashMap();
    }

    public Object put (Object key, Object val)
    {
	if (!m_map.containsKey(key))
	    {
		m_map.put (key, new TreeSet());
	    }
	Set attList = getValues(key);
        attList.add (val);
	return attList;
    }

    public void putAll (Map t)
    {
	Set keys = t.keySet ();
	for (Iterator keyIter = keys.iterator ();
	     keyIter.hasNext(); )
	    {
		Object key = keyIter.next();
		Object value = t.get (key);
		// copying a multi map
		if (value instanceof Set)
		    {
			m_map.put (key, value);
		    } else
			// copying an ordinary map
			{
			    put (key, value);
			}
	    }
    }

    public Object get (Object key)
    {
	if (m_map.containsKey(key))
	    return m_map.get(key);
	else
	    return Collections.EMPTY_SET;
    }

    public Set getValues (Object key)
    {
	return (Set)get(key);
    }

    public void clear ()
    {   m_map.clear (); }
    public Set keySet ()
    {   return m_map.keySet(); }
    public Collection values ()
    {   return m_map.values (); }
    public int size() {
	return m_map.size();
    }
    public Object remove(Object object) {
	return m_map.remove(object);
    }
    public Object removeItem (Object object)
    {
	for (Iterator iter = m_map.values().iterator();
	     iter.hasNext(); )
        {
	    Set valSet = (Set) iter.next();
	    if (valSet.contains(object))
		valSet.remove(object);
	}
	return object;
    }

    public Set entrySet() {
	return m_map.entrySet();
    }

    public boolean isEmpty() {
	return m_map.isEmpty();
    }

    public boolean containsValue(Object object) {
	// must iterate through each list
	for (Iterator attIter = m_map.values().iterator();
	     attIter.hasNext(); )
        {
	    Set valSet = (Set) attIter.next();
	    for (Iterator valIter = valSet.iterator();
		 valIter.hasNext(); )
	    {
		if (object.equals (valIter.next()))
		    return true;
	    }
	}
	return false;
    }
    public boolean setContainsValue (Object key, Object object)
    {
	Set vals = getValues (key);
	return vals.contains(object);
    }

    public boolean containsKey(Object object) {
	return m_map.containsKey(object);
    }
}