get enum name from enum value

Question

I ve read a lot about how obtain the corresponding name of an enum from its value using java  but no example seems to work for me  What is wrong     public class Extensions         public enum RelationActiveEnum               Invited 0           Active 1           Suspended 2            private final int value           private RelationActiveEnum final int value                this value   value                       and in another class I use           int dbValue   supp ACTIVE          Extensions RelationActiveEnum enumValue dbValue           String stringName   enumValue toString      Visible            OR         int dbValuee   supp ACTIVE          String stringValue   Enum GetName typeof RelationActiveEnum   dbValue     I should work  right  but it doesn t     it tells me that dbValue cannote be cast to RelationActiveEnum

User · Answer

What you can do is  RelationActiveEnum ae   Enum valueOf RelationActiveEnum class                                       RelationActiveEnum ACTIVE name      or  RelationActiveEnum ae   RelationActiveEnum valueOf                                       RelationActiveEnum ACTIVE name      or     not recommended as the ordinal might not match the value RelationActiveEnum ae   RelationActiveEnum values                                         RelationActiveEnum ACTIVE value     By if you want to lookup by a field of an enum you need to construct a collection such as a List  an array or a Map   public enum RelationActiveEnum       Invited 0       Active 1       Suspended 2        private final int code       private RelationActiveEnum final int code            this code   code             private static final Map lt Integer  RelationActiveEnum gt  BY CODE MAP   new LinkedHashMap lt  gt         static           for  RelationActiveEnum rae   RelationActiveEnum values                  BY CODE MAP put rae code  rae                        public static RelationActiveEnum forCode int code            return BY CODE MAP get code             allows you to write  String name   RelationActiveEnum forCode RelationActiveEnum ACTIVE code  name

User · Answer

You could create a lookup method  Not the most efficient  depending on the enum s size  but it works    public static String getNameByCode int code     for RelationActiveEnum e   RelationActiveEnum values         if code    e value  return e name          return null      And call it like this   RelationActiveEnum getNameByCode 3

User · Answer

In my case value was not an integer but a String  getNameByCode method can be added to the enum to get name of a String value-  enum CODE       SUCCESS  SCS    DELETE  DEL         private String status                   return the status             public String getStatus             return status                         param status                   the status to set             public void setStatus String status            this status   status             private CODE String status            this status   status             public static String getNameByCode String code            for  int i   0  i  lt  CODE values   length  i                  if  code equals CODE values   i  status                   return CODE values   i  name                      return null

User · Answer

If you want something more efficient in runtime condition  you can have a map that contains every possible choice of the enum by their value  But it ll be juste slower at initialisation of the JVM    import java util HashMap  import java util Map          Example of enum with a getter that need a value in parameter  and that return the Choice Instance     of the enum which has the same value     The value of each choice can be random      public enum MyEnum           a random choice        Choice1 4           a nother one        Choice2 2           another one again        Choice3 9           a map that contains every choices of the enum ordered by their value         private static final Map lt Integer  MyEnum gt  MY MAP   new HashMap lt Integer  MyEnum gt         static              populating the map         for  MyEnum myEnum   values                  MY MAP put myEnum getValue    myEnum                           the value of the choice        private int value                  constructor         param value the value             private MyEnum int value            this value   value                        getter of the value         return int             public int getValue             return value                        Return one of the choice of the enum by its value         May return null if there is no choice for this value          param value value         return MyEnum             public static MyEnum getByValue int value            return MY MAP get value                           inheritDoc          see java lang Enum toString               public String toString             return name           value                        Exemple of how to use this class          param args args             public static void main String   args            MyEnum enum1   MyEnum Choice1          System out println  enum1   gt     String valueOf enum1            MyEnum enum2GotByValue   MyEnum getByValue enum1 getValue             System out println  enum2GotByValue   gt     String valueOf enum2GotByValue            MyEnum enum3Unknown   MyEnum getByValue 4           System out println  enum3Unknown   gt     String valueOf enum3Unknown

User · Answer

Say we have   public enum MyEnum     Test1  Test2  Test3     To get the name of a enum variable use name     MyEnum e   MyEnum Test1  String name   e name       Returns  Test1    To get the enum from a  string  name  use valueOf     String name    Test1   MyEnum e   Enum valueOf MyEnum class  name     If you require integer values to match enum fields  extend the enum class   public enum MyEnum     Test1 1   Test2 2   Test3 3      public final int value     MyEnum final int value         this value   value          Now you can use   MyEnum e   MyEnum Test1  int value   e value       1   And lookup the enum using the integer value   MyEnum getValue int value      for MyEnum e  MyEunm values          if e value    value          return e              return null    not found

User · Answer

This is my take on it   public enum LoginState        LOGGED IN 1   LOGGED OUT 0   IN TRANSACTION -1        private int code       LoginState int code            this code   code             public int getCode             return code             public static LoginState getLoginStateFromCode int code           for LoginState e   LoginState values                 if code    e code  return e                    return LoginState LOGGED OUT    or null            And I have used it with System Preferences in Android like so   LoginState getLoginState int i        return LoginState getLoginStateFromCode                  prefs   getInt SPK IS LOGIN  LoginState LOGGED OUT getCode                      public static void setLoginState LoginState newLoginState        editor   putInt SPK IS LOGIN  newLoginState getCode         editor   commit        where pref and editor are SharedPreferences and a SharedPreferences Editor

User · Answer

Since your  value  also happens to match with ordinals you could just do   public enum RelationActiveEnum       Invited      Active      Suspended       private final int value       private RelationActiveEnum             this value   ordinal              And getting a enum from the value   int value   1  RelationActiveEnum enumInstance   RelationActiveEnum values   value     I guess an static method would be a good place to put this   public enum RelationActiveEnum        public static RelationActiveEnum fromValue int value                throws IllegalArgumentException            try                 return RelationActiveEnum values   value             catch ArrayIndexOutOfBoundsException e                  throw new IllegalArgumentException  Unknown enum value     value                            Obviously this all falls apart if your  value  isn t the same value as the enum ordinal

[java] get enum name from enum value

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