How can I lookup a Java enum from its String value

Question

I would like to lookup an enum from its string value  or possibly any other value   I ve tried the following code but it doesn t allow static in initialisers  Is there a simple way   public enum Verbosity        BRIEF  NORMAL  FULL       private static Map lt String  Verbosity gt  stringMap   new HashMap lt String  Verbosity gt          private Verbosity             stringMap put this toString    this              public static Verbosity getVerbosity String key            return stringMap get key

User · Answer

You can use the Enum  valueOf   function as suggested by Gareth Davis  amp  Brad Mace above  but make sure you handle the IllegalArgumentException that would be thrown if the string used is not present in the enum

User · Answer

Perhaps  take a look at this  Its working for me   The purpose of this is to lookup  RED  with   red color   Declaring a static map and loading the enums into it only once would bring some performance benefits if the enums are many    public class Mapper    public enum Maps        COLOR RED   red color    RED         private final String code      private final String description      private static Map lt String  String gt  mMap       private Maps String code  String description            this code   code          this description   description             public String getCode             return name               public String getDescription             return description             public String getName             return name               public static String getColorName String uri            if  mMap    null                initializeMapping                      if  mMap containsKey uri                 return mMap get uri                     return null             private static void initializeMapping             mMap   new HashMap lt String  String gt             for  Maps s   Maps values                  mMap put s code  s description                         Please put in your opinons

User · Answer

since java 8 you can initialize the map in a single line and without static block  private static Map lt String  Verbosity gt  stringMap   Arrays stream values                      collect Collectors toMap Enum  toString  Function identity

User · Answer

Use the valueOf method which is automatically created for each Enum   Verbosity valueOf  BRIEF      Verbosity BRIEF   For arbitrary values start with   public static Verbosity findByAbbr String abbr       for Verbosity v   values             if  v abbr   equals abbr                return v                      return null      Only move on later to Map implementation if your profiler tells you to   I know it s iterating over all the values  but with only 3 enum values it s hardly worth any other effort  in fact unless you have a lot of values I wouldn t bother with a Map it ll be fast enough

User · Answer

Lyle s answer is rather dangerous and I have seen it not work particularly if you make the enum a static inner class  Instead I have used something like this which will load the BootstrapSingleton maps before the enums    Edit this should not be a problem any more with modern JVMs  JVM 1 6 or greater  but I do think there are still issues with JRebel but I haven t had a chance to retest it   Load me first      public final class BootstrapSingleton               Reverse-lookup map for getting a day from an abbreviation         public static final Map lt String  Day gt  lookup   new HashMap lt String  Day gt            Now load it in the enum constructor      public enum Day            MONDAY  M    TUESDAY  T    WEDNESDAY  W            THURSDAY  R    FRIDAY  F    SATURDAY  Sa    SUNDAY  Su               private final String abbreviation           private Day String abbreviation                this abbreviation   abbreviation              BootstrapSingleton lookup put abbreviation  this                      public String getAbbreviation                 return abbreviation                     public static Day get String abbreviation                return lookup get abbreviation                     If you have an inner enum you can just define the Map above the enum definition and that  in theory  should get loaded before

User · Answer

You re close  For arbitrary values  try something like the following   public enum Day         MONDAY  M    TUESDAY  T    WEDNESDAY  W        THURSDAY  R    FRIDAY  F    SATURDAY  Sa    SUNDAY  Su           private final String abbreviation          Reverse-lookup map for getting a day from an abbreviation     private static final Map lt String  Day gt  lookup   new HashMap lt String  Day gt          static           for  Day d   Day values                  lookup put d getAbbreviation    d                        private Day String abbreviation            this abbreviation   abbreviation             public String getAbbreviation             return abbreviation             public static Day get String abbreviation            return lookup get abbreviation

User · Answer

In case it helps others  the option I prefer  which is not listed here  uses Guava s Maps functionality   public enum Vebosity       BRIEF  BRIEF        NORMAL  NORMAL        FULL  FULL         private String value      private Verbosity final String value            this value   value             public String getValue             return this value             private static ImmutableMap lt String  Verbosity gt  reverseLookup                Maps uniqueIndex Arrays asList Verbosity values     Verbosity  getValue        public static Verbosity fromString final String id            return reverseLookup getOrDefault id  NORMAL             With the default you can use null  you can throw IllegalArgumentException or your fromString could return an Optional  whatever behavior you prefer

User · Answer

And you can t use valueOf     Edit  Btw  there is nothing stopping you from using static     in an enum

User · Answer

public enum EnumRole    ROLE ANONYMOUS USER ROLE   anonymous user role    ROLE INTERNAL   internal role     private String roleName   public String getRoleName         return roleName     EnumRole String roleName        this roleName   roleName     public static final EnumRole getByValue String value       return Arrays stream EnumRole values    filter enumRole - gt  enumRole roleName equals value   findFirst   orElse ROLE ANONYMOUS USER ROLE      public static void main String   args        System out println getByValue  internal role   roleName

User · Answer

with Java 8 you can achieve with this way   public static Verbosity findByAbbr final String abbr       return Arrays stream values    filter value - gt  value abbr   equals abbr   findFirst   orElse null

User · Answer

You can define your Enum as following code     public enum Verbosity       BRIEF  NORMAL  FULL  ACTION NOT VALID     private int value      public int getValue             return this value            public static final Verbosity getVerbosityByValue int value            for Verbosity verbosity   Verbosity values                   if verbosity getValue      value              return verbosity                return ACTION NOT VALID            Override    public String toString              return   Integer this getValue    toString              See following link for more clarification

User · Answer

If you want a default value and don t want to build lookup maps  you can create a static method to handle that  This example also handles lookups where the expected name would start with a number       public static final Verbosity lookup String name            return lookup name  null              public static final Verbosity lookup String name  Verbosity dflt            if  StringUtils isBlank name                 return dflt                    if  name matches     d                    name       name                    try               return Verbosity valueOf name             catch  IllegalArgumentException e                return dflt                    If you need it on a secondary value  you would just build the lookup map first like in some of the other answers

[java] How can I lookup a Java enum from its String value?

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