List of enum values in java

Question

Is it possible to create ArrayList of enum values  and manipulate it   For example   enum MyEnum      ONE  TWO    MyEnum my   MyEnum ONE  List  lt   gt  al   new ArrayList  lt   gt     al add my   al remove al size  -1

User · Answer

This is a more generic solution  that can be use for any Enum object  so be free of used   static public List lt Object gt  constFromEnumToList Class enumType        List lt Object gt  nueva   new ArrayList lt Object gt         if  enumType isEnum              try               Class lt   gt  cls   Class forName enumType getCanonicalName                 Object   consts   cls getEnumConstants                nueva addAll Arrays asList consts              catch  ClassNotFoundException e                System out println  No se localizo la clase                        return nueva      Now you must call this way    constFromEnumToList MiEnum class

User · Answer

It is possible but you should use EnumSet instead  enum MyEnum       ONE  TWO      public static final EnumSet lt MyEnum gt  all   EnumSet of ONE  TWO

User · Answer

An enum is just another class in Java  it should be possible   More accurately  an enum is an instance of Object  http   docs oracle com javase 6 docs api java lang Enum html  So yes  it should work

User · Answer

tl dr  Can you make and edit a collection of objects from an enum  Yes    If you do not care about the order  use EnumSet  an implementation of Set    enum Animal  DOG   CAT   BIRD   BAT      Set lt Animal gt  flyingAnimals   EnumSet of  BIRD   BAT     Set lt Animal gt  featheredFlyingAnimals   flyingAnimals clone   remove  BAT       If you care about order  use a List implementation such as ArrayList  For example  we can create a list of a person   s preference in choosing a pet  in the order of their most preferred   List lt  Animal  gt  favoritePets   new ArrayList lt  gt      favoritePets add  CAT         This person prefers cats over dogs    favoritePets add  DOG            but would accept either                                This person would not accept a bird nor a bat    For a non-modifiable ordered list  use List of    List lt  Animal  gt  favoritePets   List of  CAT   DOG         This person prefers cats over dogs  but would accept either  This person would not accept a bird nor a bat     Details  The Answer  EnumSet  by Amit Deshpande and the Answer   values  by Marko Topolnik are both correct  Here is a bit more info   Enum values  The  values   method is an implicitly declared method on Enum  added by the compiler  It produces a crude array rather than a Collection  Certainly usable    Special note about documentation  Being unusual as an implicitly declared method  the  values   method is not listed among the methods on the Enum class  The method is defined in the Java Language Specification  and is mentioned in the doc for Enum valueOf   EnumSet     Fast  amp  Small  The upsides to EnumSet include    Extreme speed  Compact use of memory     To quote the class doc      Enum sets are represented internally as bit vectors  This representation is extremely compact and efficient  The space and time performance of this class should be good enough to allow its use as a high-quality  typesafe alternative to traditional int-based  bit flags   Even bulk operations  such as containsAll and retainAll  should run very quickly if their argument is also an enum set    Given this enum   enum Animal       DOG   CAT   BIRD   BAT       Make an EnumSet in one line   Set lt Animal gt  allAnimals   EnumSet allOf  Animal class      Dump to console   System out println   allAnimals       allAnimals         allAnimals    DOG  CAT  BIRD  BAT    Make a set from a subset of the enum objects   Set lt Animal gt  flyingAnimals   EnumSet of  BIRD   BAT      Look at the class doc to see many ways to manipulate the collection including adding or removing elements   Set lt Animal gt  featheredFlyingAnimals        EnumSet copyOf  flyingAnimals   remove  BAT      Natural Order  The doc promises the Iterator for EnumSet is in natural order  the order in which the values of the enum were originally declared    To quote the class doc      The iterator returned by the iterator method traverses the elements in their natural order  the order in which the enum constants are declared     Frankly  given this promise  I m confused why this is not a SortedSet  But  oh well  good enough  We can create a List from the Set if desired  Pass any Collection to constructor of ArrayList and that collection   s Iterator is automatically called on your behalf   List lt Animal gt  list   new ArrayList lt  gt   allAnimals      Dump to console   System out println  list       list      When run   list    DOG  CAT  BIRD  BAT    In Java 10 and later  you can conveniently create a non-modifiable List by passing the EnumSet  The order of the new list will be in the iterator order of the EnumSet  The iterator order of an EnumSet is the order in which the element objects of the enum were defined on that enum   List lt  Animal  gt  nonModList   List copyOf  allAnimals         Or pass Animals values

User · Answer

You can simply write  new ArrayList lt MyEnum gt  Arrays asList MyEnum values

User · Answer

Yes it is definitely possible  but you will have to do  List lt MyEnum gt  al   new ArrayList lt MyEnum gt       You can then add elements to al  al add ONE  or al add TWO

[java] List of enum values in java

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