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How to convert Enum Contants into String: Inbuilt methods of Enum in java

 In Java, every enum type inherits several built-in methods from the java.lang.Enum class, which is the base class for all enum types. These built-in methods provide functionality such as getting the name of an enum constant, comparing enum constants, and iterating over all constants.

Here are the inbuilt methods provided by the Enum class:

1. values()

  • Description: This method returns an array of all the constants of the enum type, in the order they were declared.
  • Syntax: public static T[] values()
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day[] days = Day.values();  // Get all enum constants
        
        // Loop through the array and print each day
        for (Day day : days) {
            System.out.println(day);
        }
    }
}
Output:
MONDAY
TUESDAY
WEDNESDAY
THURSDAY
FRIDAY
SATURDAY
SUNDAY

2. valueOf(String name)

  • Description: This method returns the enum constant of the specified name. The name must exactly match the identifier used to declare the enum constant (case-sensitive).
  • Syntax: public static T valueOf(String name)
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.valueOf("MONDAY");  // Get enum constant by name
        System.out.println("Today is: " + today);
    }
}
Output:
Today is: MONDAY

If you provide an invalid name, a IllegalArgumentException will be thrown:

Day invalidDay = Day.valueOf("FUNDAY");  // Throws IllegalArgumentException

3. ordinal()

  • Description: This method returns the ordinal value (position) of the enum constant in its declaration. The first constant has an ordinal of 0, the second has an ordinal of 1, and so on.
  • Syntax: public int ordinal()
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.WEDNESDAY;
        System.out.println("Ordinal of " + today + " is: " + today.ordinal());
    }
}
Output:
Ordinal of WEDNESDAY is: 2

4. name()

  • Description: This method returns the name of the enum constant exactly as declared in the enum type (case-sensitive).
  • Syntax: public String name()
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.MONDAY;
        System.out.println("Name of the day: " + today.name());
    }
}
Output:
Name of the day: MONDAY

5. compareTo(E o)

  • Description: This method compares the ordinal values of two enum constants. It returns a negative integer, zero, or a positive integer depending on whether the calling enum constant's ordinal is less than, equal to, or greater than the ordinal of the specified enum constant.
  • Syntax: public int compareTo(E o)
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.MONDAY;
        Day tomorrow = Day.TUESDAY;

        // Compare the ordinal values
        System.out.println(today.compareTo(tomorrow));  // Output: -1
    }
}
Output:
-1

6. getDeclaringClass()

  • Description: This method returns the Class object that represents the enum type.
  • Syntax: public Class<E> getDeclaringClass()
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.MONDAY;
        System.out.println("Declaring class of the enum constant: " + today.getDeclaringClass());
    }
}
Output:
Declaring class of the enum constant: class Day

7. toString()

  • Description: This method returns the name of the enum constant as a string (same as name()). You can override this method to provide a custom string representation for your enum constants.
  • Syntax: public String toString()
  • Example:
enum Day {
    MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY;
    
    @Override
    public String toString() {
        return "Day: " + name();
    }
}

public class EnumMethodsExample {
    public static void main(String[] args) {
        Day today = Day.MONDAY;
        System.out.println(today.toString());  // Custom toString method
    }
}
Output:
Day: MONDAY

Summary of Inbuilt Methods of Enum Class:

  1. values() – Returns an array of all enum constants.
  2. valueOf(String name) – Returns the enum constant matching the given name.
  3. ordinal() – Returns the ordinal value (position) of the constant.
  4. name() – Returns the name of the enum constant.
  5. compareTo(E o) – Compares ordinal values of two enum constants.
  6. getDeclaringClass() – Returns the Class object for the enum type.
  7. toString() – Returns a string representation of the enum constant.

These methods are available for all enum types and can be used to make your enum-based code more efficient and flexible.

Let me know if you need any more details!










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