Type mapping (Flutter / Dart over package:jni)

Implemented once in packages/native_api_generator/lib/src/type_mapping.dart (DartJniTypeMapper). Emitters never hard-code mappings.

Java	Dart (strict-native, default)	JNI argument	Notes
`boolean`	`bool`	as-is
`byte`	`int`	`JValueByte`	exact 8-bit width
`char`	`int` (UTF-16 code unit)	`JValueChar`	Dart has no char type
`short`	`int`	`JValueShort`
`int`	`int`	`JValueInt`
`long`	`int`	as-is	64-bit
`float`	`double`	`JValueFloat`
`double`	`double`	as-is
`java.lang.String`	`JString`	as-is	`ergonomic-dart` mode: Dart `String`, converted and released at the boundary
generated class/interface `X`	extension type `X` (over `JObject`)	as-is
type outside the closure	`JObject`	as-is	diagnostic `E016`; add it with `--entry`
`T[]` (primitive)	`JIntArray`, `JByteArray`, …	as-is
`T[]` (reference)	`JArray<T?>`	as-is
type variable `T`	erased to its first bound	as-is	diagnostic `E003` (generic generation is planned)

Nullability: @NonNull/@RecentlyNonNull → non-nullable Dart type; @Nullable → T?; unknown → T?.

Constants (static final with ConstantValue) are emitted as Dart const with the exact SDK value (long max, NaN, unicode strings preserved).

Naming#

Types: simple name with $ → _ (Handler$Callback → Handler_Callback); names that would shadow dart:core or built-ins get a trailing $ (java.lang.Object → Object$).
Members: Java names, reserved words escaped with a trailing $ (switch → switch$); members of Object/JObject are escaped (toString → toString$, release → release$).
Overloads: the primary overload (earliest API level, then fewest parameters, then simplest parameter types) keeps the plain name; others get signature suffixes (putExtra$String$long, Handler.new$Looper). The mapping is recorded in binding_map.json and in each member's doc comment.

Source: docs/architecture/type-mapping.md