syntax - Is it OK to use == on enums in Java?

Question

Is it OK to use == on enums in Java, or do I need to use .equals()? In my testing, == always works, but I'm not sure if I'm guaranteed of that. In particular, there is no .clone() method on an enum, so I don't know if it is possible to get an enum for which .equals() would return a different value than ==.

For example, is this OK:

public int round(RoundingMode roundingMode) {
  if(roundingMode == RoundingMode.HALF_UP) {
    //do something
  } else if (roundingMode == RoundingMode.HALF_EVEN) {
    //do something
  }
  //etc
}

Or do I need to write it this way:

public int round(RoundingMode roundingMode) {
  if(roundingMode.equals(RoundingMode.HALF_UP)) {
    //do something
  } else if (roundingMode.equals(RoundingMode.HALF_EVEN)) {
    //do something
  }
  //etc
}

Answer 1

Just my 2 cents: Here is the code for Enum.java, as published by Sun, and part of the JDK:

public abstract class Enum<E extends Enum<E>>
    implements Comparable<E>, Serializable {

    // [...]

    /**
     * Returns true if the specified object is equal to this
     * enum constant.
     *
     * @param other the object to be compared for equality with this object.
     * @return  true if the specified object is equal to this
     *          enum constant.
     */
    public final boolean equals(Object other) { 
        return this==other;
    }


}