How to get all enum values in Java?

Question

I came across this problem that I without knowing the actual enum type I need to iterate its possible values.

if (value instanceof Enum){
   Enum enumValue = (Enum)value;
}

Any ideas how to extract from enumValue its possible values ?

Solution 1

Call Class#getEnumConstants to get the enum’s elements (or get null if not an enum class).

Object[] possibleValues = enumValue.getDeclaringClass().getEnumConstants();

Solution 2

YourEnumClass[] yourEnums = YourEnumClass.class.getEnumConstants();

Or

YourEnumClass[] yourEnums = YourEnumClass.values();

Solution 3

Enums are just like Classes in that they are typed. Your current code just checks if it is an Enum without specifying what type of Enum it is a part of.

Because you haven't specified the type of the enum, you will have to use reflection to find out what the list of enum values is.

You can do it like so:

enumValue.getDeclaringClass().getEnumConstants() 

This will return an array of Enum objects, with each being one of the available options.

Solution 4

values method of enum

enum.values() method which returns all enum instances.

  public class EnumTest {
        private enum Currency {
        PENNY("1 rs"), NICKLE("5 rs"), DIME("10 rs"), QUARTER("25 rs");
        private String value;
        private Currency(String brand) {
              this.value = brand;
        }
        @Override
        public String toString() {
              return value;
        }
  }
  public static void main(String args[]) {
        Currency[] currencies = Currency.values();
        // enum name using name method
        // enum to String using toString() method
        for (Currency currency : currencies) {
              System.out.printf("[ Currency : %s,
                         Value : %s ]%n",currency.name(),currency);
        }
  }
}

http://javaexplorer03.blogspot.in/2015/10/name-and-values-method-of-enum.html

Solution 5

... or MyEnum.values() ? Or am I missing something?

View more solutions

Comments

[ColinD]

Yes, the actual class of the enum is not available here to make a static method call on, just an instance of some subtype of Enum.

[Peter Kriens]

Why do you use the getDeclaringClass()?

[ColinD]

@PeterKriens: Because getClass() on an enum object may return a subtype of the enum type itself (if, say, the enum constant overrides a method from the enum type). getDeclaringClass() returns the enum type that declared that constant, which is what you want here.

[Peter Kriens]

Thanks! I had not realised that case but you are right, the constant can be of an anonymous inner class.

[zeratul021]

However, this is not generic. Question is about the case when only have the Enum object. So you need to either go via declaring class or better, via EnumSet.