Java: Enum vs. Int

Question

When using flags in Java, I have seen two main approaches. One uses int values and a line of if-else statements. The other is to use enums and case-switch statements.

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Answer 1

One of the reasons you will see some code using int flags instead of an enum is that Java did not have enums until Java 1.5

So if you are looking at code that was originally written for an older version of Java, then the int pattern was the only option available.

There are a very small number of places where using int flags is still preferable in modern Java code, but in most cases you should prefer to use an enum, due to the type safety and expressiveness that they offer.

In terms of efficiency, it will depend on exactly how they are used. The JVM handles both types very efficiently, but the int method would likely be slightly more efficient for some use cases (because they are handled as primitive rather than objects), but in other cases, the enum would be more efficient (because it doesn't need to go throw boxing/unboxing).

You would be hard pressed to find a situation in which the efficiency difference would be in any way noticeable in a real world application, so you should make the decision based on the quality of the code (readability and safety), which should lead you to use an enum 99% of the time.