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 */
017 package org.apache.commons.lang3;
018
019 import java.util.ArrayList;
020 import java.util.Arrays;
021 import java.util.LinkedHashMap;
022 import java.util.List;
023 import java.util.Map;
024
025 /**
026 * <p>Utility library to provide helper methods for Java enums.</p>
027 *
028 * <p>#ThreadSafe#</p>
029 *
030 * @since 3.0
031 * @version $Id: EnumUtils.java 1088899 2011-04-05 05:31:27Z bayard $
032 */
033 public class EnumUtils {
034
035 /**
036 * This constructor is public to permit tools that require a JavaBean
037 * instance to operate.
038 */
039 public EnumUtils() {
040 }
041
042 /**
043 * <p>Gets the {@code Map} of enums by name.</p>
044 *
045 * <p>This method is useful when you need a map of enums by name.</p>
046 *
047 * @param <E> the type of the enumeration
048 * @param enumClass the class of the enum to query, not null
049 * @return the modifiable map of enum names to enums, never null
050 */
051 public static <E extends Enum<E>> Map<String, E> getEnumMap(Class<E> enumClass) {
052 Map<String, E> map = new LinkedHashMap<String, E>();
053 for (E e: enumClass.getEnumConstants()) {
054 map.put(e.name(), e);
055 }
056 return map;
057 }
058
059 /**
060 * <p>Gets the {@code List} of enums.</p>
061 *
062 * <p>This method is useful when you need a list of enums rather than an array.</p>
063 *
064 * @param <E> the type of the enumeration
065 * @param enumClass the class of the enum to query, not null
066 * @return the modifiable list of enums, never null
067 */
068 public static <E extends Enum<E>> List<E> getEnumList(Class<E> enumClass) {
069 return new ArrayList<E>(Arrays.asList(enumClass.getEnumConstants()));
070 }
071
072 /**
073 * <p>Checks if the specified name is a valid enum for the class.</p>
074 *
075 * <p>This method differs from {@link Enum#valueOf} in that checks if the name is
076 * a valid enum without needing to catch the exception.</p>
077 *
078 * @param <E> the type of the enumeration
079 * @param enumClass the class of the enum to query, not null
080 * @param enumName the enum name, null returns false
081 * @return true if the enum name is valid, otherwise false
082 */
083 public static <E extends Enum<E>> boolean isValidEnum(Class<E> enumClass, String enumName) {
084 if (enumName == null) {
085 return false;
086 }
087 try {
088 Enum.valueOf(enumClass, enumName);
089 return true;
090 } catch (IllegalArgumentException ex) {
091 return false;
092 }
093 }
094
095 /**
096 * <p>Gets the enum for the class, returning {@code null} if not found.</p>
097 *
098 * <p>This method differs from {@link Enum#valueOf} in that it does not throw an exception
099 * for an invalid enum name.</p>
100 *
101 * @param <E> the type of the enumeration
102 * @param enumClass the class of the enum to query, not null
103 * @param enumName the enum name, null returns null
104 * @return the enum, null if not found
105 */
106 public static <E extends Enum<E>> E getEnum(Class<E> enumClass, String enumName) {
107 if (enumName == null) {
108 return null;
109 }
110 try {
111 return Enum.valueOf(enumClass, enumName);
112 } catch (IllegalArgumentException ex) {
113 return null;
114 }
115 }
116
117 }