How to get all enum values in Java?

I came acr开发者_如何学Pythonoss 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 ?

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

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

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

Or

YourEnumClass[] yourEnums = YourEnumClass.values();

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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

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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.

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

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Here, Role is an enum which contains the following values [ADMIN, USER, OTHER].

List<Role> roleList = Arrays.asList(Role.values());
roleList.forEach(role -> {
    System.out.println(role);
    });

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One can also use the java.util.EnumSet like this

@Test
void test(){
    Enum aEnum =DayOfWeek.MONDAY;
    printAll(aEnum);
}

void printAll(Enum value){
    Set allValues = EnumSet.allOf(value.getClass());
    System.out.println(allValues);
}

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Any one who is trying to fetch all the values as list can simply do this.

Arrays.asList(YouEnumClass.values())