java field declarations in interface

Field (Constant) Declarations
The materials of action are variable,
but the use we make of them should be constant.

ConstantDeclaration:
ConstantModifiersopt Type VariableDeclarators ;
ConstantModifiers:
ConstantModifier
ConstantModifier ConstantModifers
ConstantModifier:
one of
Annotation
public
static
final

• Every field declaration in the body of an interface is implicitly public,
  static, and final. It is permitted to redundantly specify any or all of these modifiers
  for such fields.
• If an annotation a on a fielddeclaration corresponds to an annotation type T,
  and T has a (meta-)annotation m that corresponds to annotation.Target, then m
  must have an element whose value is annotation.ElementType.FIELD, or a
  compile-time error occurs. Annotation modifiers are described further in
  If the interface declares a field with a certain name, then the declaration of
  that field is said to hide any and all accessible declarations of fields with the same
  name in superinterfaces of the interface.
• It is a compile-time error for the body of an interface
  declaration to declare
  two fields with the same name.
• It is possible for an interface to inherit more than one field with the same
  name .
• Such a situation does not in itself cause a compile-time error.
• However, any attempt within the body of the interface to refer to either field by its
• simple name will result in a compile-time error, because such a reference is ambiguous.

Read More