This inner class extends AttributedCharacterIterator.Attribute and serves as the common superclass for DateFormat.Field , MessageFormat.Field , and NumberFormat.Field . See those specific subclasses for details. public static class Format.Field extends AttributedCharacterIterator.Attribute { // Protected Constructors protected Field (String name ); } SubclassesDateFormat.Field , MessageFormat.Field , NumberFormat.Field Passed ToFieldPosition.FieldPosition( ) Returned ByFieldPosition.getFieldAttribute( ) |