Enums and @IntDefs

Enumerations serve the purpose of representing a group of named constants in a programming language
We often use Enums to make our cool, restricted group of values tht a function or statement could take.
But they are usually considered a bad practise in android because Enums often require more than twice as much memory as static constants.

Enter IntDef

@IntDef is a way of replacing an integer enum where there's a parameter that should only accept explicit int values.We can use IntDef to ensure that the value is one of the expected values by adding this annotation. For eg:

public class example {
   @IntDef( {Type.TYPE_MUSIC,Type.TYPE_PHOTO,Type.TYPE_TEXT})
    public  @interface  Type{
        int TYPE_MUSIC = 0;
        int TYPE_PHOTO = 21;
        int TYPE_TEXT = 42;
    }

  // Mark the argument as restricted to these enumerated types
  public void getItemType(@Type int itemType) {
    int res = itemType;
  }
}

The function will allow user to pass any integer value, but will give a lint warning if value is not Type.TYPE_MUSIC,Type.TYPE_PHOTOorType.TYPE_TEXT(yes, even if 0,21 or 42 are passed directly too ).