de.decoit.simu.cbor.xml.dictionary.DictionaryProvider.java Source code

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Here is the source code for de.decoit.simu.cbor.xml.dictionary.DictionaryProvider.java

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/* 
 * Copyright 2015 DECOIT GmbH
 *
 * 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 de.decoit.simu.cbor.xml.dictionary;

import java.util.HashMap;
import java.util.Map;
import org.apache.commons.lang3.StringUtils;

/**
 * This utility class provides a singleton instance of {@link Dictionary}.
 *
 * @author Thomas Rix (rix@decoit.de)
 */
public abstract class DictionaryProvider {
    private static Dictionary instance = null;
    private static final Map<String, Dictionary> namedInstances = new HashMap<>();

    /**
     * Retrieve the singleton Dictionary instance.
     *
     * @return Dictionary instance
     */
    public static Dictionary getInstance() {
        if (instance == null) {
            instance = new Dictionary();
        }

        return instance;
    }

    /**
     * Retrieve a Dictionary instance that may be referenced by its name.
     * If no instance is registered under this name, a new one is created.
     *
     * @param name Reference name for the requested instance
     * @return The Dictionary instance referenced by the provided name
     */
    public static Dictionary getNamedInstance(String name) {
        if (StringUtils.isBlank(name)) {
            throw new IllegalArgumentException("Instance name must not be blank");
        }

        if (namedInstances.get(name) == null) {
            namedInstances.put(name, new Dictionary());
        }

        return namedInstances.get(name);
    }

    /**
     * Remove the Dictionary instance referenced by the specified name.
     * The instance will be removed from the storage of named instances and its clear() method is called to clear any content
     * inside the Dictionary.
     *
     * @param name Reference name of the instance to be removed
     */
    public static void removeNamedInstance(String name) {
        Dictionary rem = namedInstances.remove(name);

        if (rem != null) {
            rem.clear();
        }
    }

    static boolean hasNamedInstance(String name) {
        return namedInstances.containsKey(name);
    }
}