Comparing Java Enum Members: == or equals()

While working with Java enums, a common question arises regarding the appropriate operator to use for comparing enum members. Traditionally, developers have employed the .equals() method, as seen in:

public useEnums(SomeEnum a) {
    if (a.equals(SomeEnum.SOME_ENUM_VALUE)) {
        ...
    }
}

However, some examples demonstrate the use of the == operator for comparison:

public useEnums2(SomeEnum a) {
    if (a == SomeEnum.SOME_ENUM_VALUE) {
        ...
    }
}

Which of these operators should be preferred for comparing enum members?

Technical Equivalence and Null Safety

Interestingly, both approaches are technically correct. The source code for .equals() in Java enums reveals that it simply delegates to ==. However, there is a subtle difference: == also provides null safety.

By utilizing ==, you can safeguard against potential null references in enum member comparisons. This aspect becomes especially relevant when working with code inherited from legacy systems or third-party libraries where null values may occasionally occur.

Recommendation

Considering the subtle advantage of null safety and the fact that both == and .equals() essentially perform the same comparison, it is generally advisable to use == when comparing Java enum members. This recommendation aligns with the author's personal preference as well.