001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.util.lang;
018
019import java.util.ArrayList;
020import java.util.List;
021import java.util.Map;
022
023import org.apache.wicket.util.string.StringValue;
024
025
026/**
027 * A base class for defining enumerated types. Since this class extends StringValue, every
028 * enumerated type subclass is a StringValue that can be manipulated, converted and displayed in
029 * useful ways. In addition to constructing a type with the given name, lists are kept of all
030 * enumeration values by subclass. The list of available values in the enumeration represented by a
031 * given subclass can be retrieved by calling getValues(Class).
032 * 
033 * @author Jonathan Locke
034 */
035public abstract class EnumeratedType extends StringValue
036{
037        /**
038         * 
039         */
040        private static final long serialVersionUID = 1L;
041        /** Map of type values by class */
042        private static final Map<String, List<EnumeratedType>> valueListByClass = Generics.newConcurrentHashMap();
043
044        /**
045         * Constructor.
046         * 
047         * @param name
048         *            Name of this enumerated type value
049         */
050        public EnumeratedType(final String name)
051        {
052                super(name);
053
054                // Add this object to the list of values for our subclass
055                getValues(getClass()).add(this);
056        }
057
058        /**
059         * Gets the enumerated type values for a given subclass of EnumeratedType.
060         * 
061         * @param c
062         *            The enumerated type subclass to get values for
063         * @return List of all values of the given subclass
064         */
065        public static List<EnumeratedType> getValues(final Class<? extends EnumeratedType> c)
066        {
067                // Get values for class
068                List<EnumeratedType> valueList = valueListByClass.get(c.getName());
069
070                // If no list exists
071                if (valueList == null)
072                {
073                        // create lazily
074                        valueList = new ArrayList<>();
075                        valueListByClass.put(c.getName(), valueList);
076                }
077
078                return valueList;
079        }
080
081        /**
082         * Method to ensure that == works after deserialization
083         * 
084         * @return object instance
085         * @throws java.io.ObjectStreamException
086         */
087        public Object readResolve() throws java.io.ObjectStreamException
088        {
089                EnumeratedType result = this;
090                List<EnumeratedType> values = getValues(getClass());
091                for (EnumeratedType value : values)
092                {
093                        if ((value.toString() != null) && value.toString().equals(this.toString()))
094                        {
095                                result = value;
096                                break;
097                        }
098                }
099                return result;
100        }
101}