com.vaadin.terminal.KeyMapper Maven / Gradle / Ivy

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Vaadin is a web application framework for Rich Internet Applications (RIA). Vaadin enables easy development and maintenance of fast and secure rich web applications with a stunning look and feel and a wide browser support. It features a server-side architecture with the majority of the logic running on the server. Ajax technology is used at the browser-side to ensure a rich and interactive user experience.

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/* 
 * Copyright 2011 Vaadin Ltd.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.vaadin.terminal;

import java.io.Serializable;
import java.util.Hashtable;

/**
 * KeyMapper is the simple two-way map for generating textual keys
 * for objects and retrieving the objects later with the key.
 * 
 * @author Vaadin Ltd.
 * @version
 * 6.8.8
 * @since 3.0
 */
@SuppressWarnings("serial")
public class KeyMapper implements Serializable {

    private int lastKey = 0;

    private final Hashtable objectKeyMap = new Hashtable();

    private final Hashtable keyObjectMap = new Hashtable();

    /**
     * Gets key for an object.
     * 
     * @param o
     *            the object.
     */
    public String key(Object o) {

        if (o == null) {
            return "null";
        }

        // If the object is already mapped, use existing key
        String key = objectKeyMap.get(o);
        if (key != null) {
            return key;
        }

        // If the object is not yet mapped, map it
        key = String.valueOf(++lastKey);
        objectKeyMap.put(o, key);
        keyObjectMap.put(key, o);

        return key;
    }

    /**
     * Retrieves object with the key.
     * 
     * @param key
     *            the name with the desired value.
     * @return the object with the key.
     */
    public Object get(String key) {

        return keyObjectMap.get(key);
    }

    /**
     * Removes object from the mapper.
     * 
     * @param removeobj
     *            the object to be removed.
     */
    public void remove(Object removeobj) {
        final String key = objectKeyMap.get(removeobj);

        if (key != null) {
            objectKeyMap.remove(removeobj);
            keyObjectMap.remove(key);
        }
    }

    /**
     * Removes all objects from the mapper.
     */
    public void removeAll() {
        objectKeyMap.clear();
        keyObjectMap.clear();
    }
}