Java Check if enum contains a given string

Question

Here s my problem - I m looking for  if it even exists  the enum equivalent of ArrayList contains      Here s a sample of my code problem   enum choices  a1  a2  b1  b2    if choices     a1      do this      Now  I realize that an ArrayList of Strings would be the better route here but I have to run my enum contents through a switch case elsewhere  Hence my problem   Assuming something like this doesn t exist  how could I go about doing it

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I would just write   Arrays stream Choice values    map Enum  name  collect Collectors toList    contains  a1      Enum equals only works with object compare

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enum are pretty powerful in Java  You could easily add a contains method to your enum  as you would add a method to a class    enum choices     a1  a2  b1  b2     public boolean contains String s            if  s equals  a1      s equals  a2      s equals  b1      s equals  b2              return true        return false

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com google common collect Sets newHashSet MyEnum values    contains  myValue

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you can also use   com google common base Enums  Enums getIfPresent varEnum class  varToLookFor  returns an Optional  Enums getIfPresent fooEnum class  myVariable  isPresent     Enums getIfPresent fooEnum class  myVariable  get   fooEnum OTHERS

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This should do it   public static boolean contains String test         for  Choice c   Choice values              if  c name   equals test                 return true                       return false      This way means you do not have to worry about adding additional enum values later  they are all checked   Edit  If the enum is very large you could stick the values in a HashSet   public static HashSet lt String gt  getEnums        HashSet lt String gt  values   new HashSet lt String gt        for  Choice c   Choice values            values add c name            return values      Then you can just do  values contains  your string   which returns true or false

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You can first convert the enum to List and then use list contains method  enum Choices A1  A2  B1  B2    List choices   Arrays asList Choices values        compare with enum value  if choices contains Choices A1         do something      compare with String value if choices contains Choices valueOf  A1           do something

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Java Streams provides elegant way to do that  Stream of MyEnum values    anyMatch v - gt  v name   equals strValue     Returns  true if any elements of the stream match the provided value  otherwise false

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This combines all of the approaches from previous methods and should have equivalent performance   It can be used for any enum  inlines the  Edit  solution from  Richard H  and uses Exceptions for invalid values like  bestsss   The only tradeoff is that the class needs to be specified  but that turns this into a two-liner   import java util EnumSet   public class HelloWorld    static enum Choices  a1  a2  b1  b2   public static  lt E extends Enum lt E gt  gt  boolean contains Class lt E gt   enumClass  String value        try           return EnumSet allOf  enumClass  contains Enum valueOf  enumClass  value              catch  Exception e            return false            public static void main String   args        for  String value   new String     a1    a3   null             System out println contains Choices class  value

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solution to check whether value is present as well get enum value in return    protected TradeType getEnumType String tradeType        if  tradeType    null            if  EnumUtils isValidEnum TradeType class  tradeType                 return TradeType valueOf tradeType                       return null

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Set of CustomType values          contains customTypevalue

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A couple libraries have been mentioned here  but I miss the one that I was actually looking for  Spring   There is the ObjectUtils containsConstant which is case insensitive by default  but can be strict if you want  It is used like this   if ObjectUtils containsConstant Choices values     SOME CHOISE   true       do stuff     Note  I used the overloaded method here to demonstrate how to use case sensitive check  You can omit the boolean to have case insensitive behaviour   Be careful with large enums though  as they don t use the Map implementation as some do     As a bonus  it also provides a case insensitive variant of the valueOf  ObjectUtils caseInsensitiveValueOf

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You can use valueOf  a1   if you want to look up by String

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I don t think there is  but you can do something like this   enum choices  a1  a2  b1  b2    public static boolean exists choices choice       for choice aChoice   choices values            if aChoice    choice             return true                  return false      Edit   Please see Richard s version of this as it is more appropriate as this won t work unless you convert it to use Strings  which Richards does

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Few assumptions  1  No try catch  as it is exceptional flow control 2   contains  method has to be quick  as it usually runs several times  3  Space is not limited  common for ordinary solutions     import java util HashSet  import java util Set   enum Choices       a1  a2  b1  b2       private static Set lt String gt   values   new HashSet lt  gt             O n  - runs once     static          for  Choices choice   Choices values                   values add choice name                             O 1  - runs several times     public static boolean contains String value           return  values contains value

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I created the next class for this validation  public class EnumUtils        public static boolean isPresent Enum enumArray    String name            for  Enum element  enumArray                 if element toString   equals name                   return true                    return false             example of usage    public ArrivalEnum findArrivalEnum String name         if   EnumUtils isPresent ArrivalEnum values    name           throw new EnumConstantNotPresentException ArrivalEnum class  Arrival value must be  FROM AIRPORT  or  TO AIRPORT           return ArrivalEnum valueOf name

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This approach can be used to check any Enum  you can add it to an Utils class   public static  lt T extends Enum lt T gt  gt  boolean enumContains Class lt T gt  enumerator  String value        for  T c   enumerator getEnumConstants              if  c name   equals value                 return true                      return false      Use it this way   boolean isContained   Utils enumContains choices class   value

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Even better   enum choices      a1  a2  b1  b2     public static boolean contains String s            for choices choice values               if  choice name   equals s                  return true        return false

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EnumUtils isValidEnum might be the best option if you like to import Apache commons lang3  if not following is a generic function I would use as an alternative  private  lt T extends Enum lt T gt  gt  boolean enumValueExists Class lt T gt  enumType  String value        boolean result      try           Enum valueOf enumType  value           result   true        catch  IllegalArgumentException e            result   false            return result      And use it as following if  enumValueExists MyEnum class  configValue            happy code   else          angry code

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It is an enum  those are constant values so if its in a switch statement its just doing something like this   case  val1 case  val2   Also why would you need to know what is declared as a constant

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If you are Using Java 8 or above  you can do this     boolean isPresent String testString         return Stream of Choices values    map Enum  name  collect Collectors toSet    contains testString

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This one works for me   Arrays asList YourEnum values    toString   contains  valueToCheck

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Use the Apache commons lang3 lib instead   EnumUtils isValidEnum MyEnum class  myValue

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If you are using Java 1 8  you can choose Stream   Lambda to implement this   public enum Period       DAILY  WEEKLY       This is recommended Arrays stream Period values    anyMatch  t  - gt  t name   equals  DAILY1       May throw java lang IllegalArgumentException Arrays stream Period values    anyMatch Period valueOf  DAILY    equals

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public boolean contains Choices value       return EnumSet allOf Choices class  contains value

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Guavas Enums could be your friend  Like e g  this   enum MyData       ONE      TWO     Test public void test          if   Enums getIfPresent MyData class   THREE   isPresent              System out println  THREE is not here

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You can use this  YourEnum  A1  A2  B1  B2   boolean contains String str        return Sets newHashSet YourEnum values    contains str                                         Update suggested by  wightwulf1944 is incorporated to make the solution more efficient

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With guava it s even simpler   boolean isPartOfMyEnum String myString    return Lists newArrayList MyEnum values   toString    contains myString

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You can use Enum valueOf    enum Choices A1  A2  B1  B2    public class MainClass     public static void main String args          Choices day       try          day   Choices valueOf  A1             yes       catch  IllegalArgumentException ex                nope         If you expect the check to fail often  you might be better off using a simple loop as other have shown - if your enums contain many values  perhaps builda  HashSet or similar of your enum values converted to a string and query that HashSet instead

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Why not combine Pablo s reply with a valueOf     public enum Choices       a1  a2  b1  b2       public static boolean contains String s            try               Choices valueOf s               return true            catch  Exception e                return false

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You can make it as a contains method   enum choices  a1  a2  b1  b2   public boolean contains String value       try          EnumSet allOf choices class  contains Enum valueOf choices class  value            return true       catch  Exception e            return false             or you can just use it with your code block   try      EnumSet allOf choices class  contains Enum valueOf choices class   a1           do something  catch  Exception e          do something else

[java] Java: Check if enum contains a given string?

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