multimap.java.svn-base

来自「cqME :java framework for TCK test.」· SVN-BASE 代码 · 共 185 行

/*
 * $Id$
 *
 * Copyright 1996-2007 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 only, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License version 2 for more details (a copy is
 * included at /legal/license.txt).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this work; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.com if you need additional
 * information or have any questions.
 *
 */

package com.sun.tck.j2me.utils;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;

/**
 * This class represents data structure for one to many relations.
 * It stores list of the elements for each key. The map is HashMap for
 * quick access.
 */
public class MultiMap<Key, Value> {
    private boolean isCopy;
    private boolean isSynchronized;
    private boolean isSyncOptimized;
    private HashMap<Key, List<Value>> map = new HashMap<Key, List<Value>>();
    private boolean isUniq;

    /**
     * Creates the instance with the given properties.
     * @param isCopy if this parameter is true, then the copy of the
     * List always returned, otherwise the internal list is returned
     * and modification of the returned list cause modification of the MultiMap.
     * Note that isSynchronized and isSyncOptimized are ignored if this
     * parameter is true.
     * @param isSyncOptimized if this parameter is true, than adding and
     * removing of the values will cause creation of the new List. It allows do
     * not synchronize returned list.
     * Note that  isSynchronized parameter is ignored of this parameter is true.
     * @param isSynchronized If the value is true, then the synchronized is
     * returned.
     * @param isUniq If the parameter is true, then the List will contain only
     * unique values.
     */
    public MultiMap(boolean isCopy, boolean isSyncOptimized, boolean isSynchronized, boolean isUniq) {
        this.isCopy = isCopy;
        // there are no needs in the the creation of the synchronized list
        // if it is cloned during update.
        this.isSynchronized = isSynchronized && (!isSyncOptimized);
        // there are no needs in the creation of the copy during map update
        // if clone is returned by get operations
        this.isSyncOptimized = isSyncOptimized && (!isCopy);
        this.isUniq = isUniq;
    }

    /**
     * creates the default MultiMap, where all properties are false.
     *
     */
    public MultiMap() {
        this(false, false, false, false);
    }

    /**
     * Returns values mapped with the given key as Iterator.
     * Note that this method never returns null.
     */
    public Iterator<Value> iterator(Key key) {
        return getList(key).iterator();
    }

    /**
     * Returns values mapped with the given key as List.
     * Note that this method never returns null.
     */
    public List<Value> getList(Key key) {
        List<Value> retVal;
        synchronized (map) {
           retVal = map.get(key);
           if ((retVal == null) && (!isCopy)) {
               retVal = new ArrayList<Value>();
               map.put(key, retVal);
           }
        }
        if (retVal == null) {
            return new ArrayList<Value>();
        } else if (isCopy) {
            ArrayList<Value> copy = new ArrayList<Value>();
            copy.addAll(retVal);
            return copy;
        } else {
            return retVal;
        }
    }

    /**
     * Adds value to the list associated with the given key.
     */
    public void addValue(Key key, Value value) {
        List<Value> list;
        synchronized (map) {
            List<Value> old = map.get(key);
            if (isSyncOptimized || (old == null)) {
                list = new ArrayList<Value>();
                if (isSynchronized) {
                    list = Collections.synchronizedList(list);
                }
                map.put(key, list);
                if (old != null) {
                    list.addAll(old);
                }
            } else {
                list = old;
            }
        }
        synchronized (list) {
            if (!list.contains(value) || this.isUniq) {
                list.add(value);
            }
        }
    }

    /**
     * Removes the value from the list associated with the given key.
     * @param key given key
     * @param value value to be removed.
     * @return true if the list contained this element.
     */
    public boolean removeValue(Key key, Value value) {
        List<Value> list;
        synchronized (map) {
            List<Value> old = map.get(key);
            if (old == null) {
                return false;
            }
            if (isSyncOptimized) {
                list = new ArrayList<Value>();
                map.put(key, list);
                list.addAll(old);
            } else {
                list = old;
            }
        }
        return list.remove(value);
    }

    /**
     * Removes all values associated with the given key.
     */
    public List<Value> clearValues(Object key) {
        synchronized (map) {
            List<Value> retVal = map.remove(key);
            return (retVal == null) ? new ArrayList<Value>() : retVal;
        }
    }

    /**
     * removes all elements.
     */
    public void clear() {
        synchronized (map) {
            map.clear();
        }
    }
}