Working with Enums in android

Question

I am almost done with a calculation activity I am working with in android for my app  I try to create a Gender Enum  but for some reason getting Syntax error  insert  EnumBody  to complete EnumDeclaration   public static enum Gender       static               Female   new Gender  Female   1           Gender   arrayOfGender   new Gender 2           arrayOfGender 0    Male          arrayOfGender 1    Female          ENUM VALUES   arrayOfGender            I have also tried it without the static    but I get the same syntax error

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public enum Gender       MALE      FEMALE

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There has been some debate around this point of contention  but even in the most recent documents android suggests that it s not such a good idea to use enums in an android application  The reason why is because they use up more memory than a static constants variable  Here is a document from a page of 2014 that advises against the use of enums in an android application  http   developer android com training articles memory html Overhead  I quote      Be aware of memory overhead      Be knowledgeable about the cost and overhead of the language and   libraries you are using  and keep this information in mind when you   design your app  from start to finish  Often  things on the surface   that look innocuous may in fact have a large amount of overhead    Examples include          Enums often require more than twice as much memory as static   constants  You should strictly avoid using enums on Android    Every class in Java  including anonymous inner classes  uses about 500 bytes of code    Every class instance has 12-16 bytes of RAM overhead     Putting a single entry into a HashMap requires the allocation of an   additional   entry object that takes 32 bytes  see the previous section about   optimized data containers           A few bytes here and there quickly add   up   app designs that are class- or object-heavy will suffer from this   overhead  That can leave you in the difficult position of looking at a   heap analysis and realizing your problem is a lot of small objects   using up your RAM    There has been some places where they say that these tips are outdated and no longer valuable  but the reason they keep repeating it  must be there is some truth to it  Writing an android application is something you should keep as lightweight as possible for a smooth user experience  And every little inch of performance counts

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Android s preferred approach is int constants enforced with  IntDef   public static final int GENDER MALE   1  public static final int GENDER FEMALE   2    Retention RetentionPolicy SOURCE   IntDef   GENDER MALE  GENDER FEMALE   public  interface Gender       Example usage    void exampleFunc  Gender int gender      switch gender      case GENDER MALE        break    case GENDER FEMALE          TODO      break          Docs  https   developer android com studio write annotations html enum-annotations

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According to this Video if you use the ProGuard you don t need even think about Enums performance issues       Proguard can in many situations optimize Enums to INT values on your behalf so really don t need to think about it or do any work

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Where on earth did you find this syntax  Java Enums are very simple  you just specify the values   public enum Gender      MALE     FEMALE     If you want them to be more complex  you can add values to them like this   public enum Gender       MALE  Male   0       FEMALE  Female   1        private String stringValue      private int intValue      private Gender String toString  int value            stringValue   toString          intValue   value              Override     public String toString             return stringValue            Then to use the enum  you would do something like this   Gender me   Gender MALE

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As commented by Chris  enums require much more memory on Android that adds up as they keep being used everywhere  You should try IntDef or StringDef instead  which use annotations so that the compiler validates passed values   public abstract class ActionBar        IntDef  NAVIGATION MODE STANDARD  NAVIGATION MODE LIST  NAVIGATION MODE TABS    Retention RetentionPolicy SOURCE  public  interface NavigationMode     public static final int NAVIGATION MODE STANDARD   0  public static final int NAVIGATION MODE LIST   1  public static final int NAVIGATION MODE TABS   2    NavigationMode public abstract int getNavigationMode     public abstract void setNavigationMode  NavigationMode int mode     It can also be used as flags  allowing for binary composition  OR   AND operations    EDIT  It seems that transforming enums into ints is one of the default optimizations in Proguard

[android] Working with Enums in android

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