Schema introspection

Since 1.9.0 the field layout of a @Record class can be queried at runtime through the FixedFormatIntrospector interface, implemented by FixedFormatManagerImpl. This serves tooling built on top of the annotated schema — documentation generators, UI form builders, format negotiation (detecting offset/length drift between record class versions), and layout assertions in tests — without re-implementing annotation scanning.

FixedFormatIntrospector introspector = new FixedFormatManagerImpl();

for (FieldInfo field : introspector.introspect(CustomerRecord.class)) {
  System.out.printf("%-15s offset=%2d length=%2d type=%s%n",
      field.getPropertyName(), field.getOffset(), field.getLength(),
      field.getDataType().getSimpleName());
}

customerId      offset= 1 length=10 type=String
customerName    offset=11 length=20 type=String

FixedFormatIntrospector is a separate interface rather than an addition to FixedFormatManager, so existing third-party manager implementations stay source and binary compatible; callers that only need schema access can depend on the narrow contract.

FieldInfo

introspect() returns one immutable FieldInfo per effective @Field, ordered by offset. A getter carrying @Fields contributes one entry per inner @Field.

Accessor	Meaning
getPropertyName()	Bean-style property name (getCustomerId() → customerId); for Java records, the component name as-is
getOffset() / getLength()	1-based offset; length -1 = rest-of-line
getDataType()	Declared Java type (the collection/array type for repeating fields)
getEffectiveAlignment()	Resolved LEFT/RIGHT — record-level defaults already applied, never INHERIT
getPaddingChar()	Padding character
getNullChar() / getNullValue()	Null sentinels (UNSET_NULL_CHAR / "" when not configured)
getFormatterClass()	Configured formatter (ByTypeFormatter unless overridden)
getRepeatCount()	count attribute; 1 for non-repeating fields
isNestedRecord()	true when the field type is itself a @Record class

Validation preflight

introspect() triggers the same one-time metadata build and annotation validation as load()/export(), so it doubles as a startup preflight check: an invalid configuration (bad date pattern, enum too wide, misconfigured null sentinel, …) throws FixedFormatException at introspection time. For build-time validation, see Compile-time validation.

Performance: the underlying scan and validation run once per class (the same cached metadata used by load()/export()); each introspect() call performs only an O(number of fields) mapping with no I/O and no reflection beyond the cached metadata.