jni

Added

• JCharSequence bindings for java.lang.CharSequence (including AsRef<JCharSequence> + .as_char_sequence() for JString) (#793)
• bind_java_type supports non_null qualifier/property for methods and fields to map null references to Error::NullPtr (#795)
• bind_java_type supports #[cfg()] attributes on methods and fields, to conditionally compile them based on features or other cfg conditions (#797)
• JValueOwned::check_null() + ::is_null() methods for ergonomic null checks on owned (returned) values (#798)
• More readable type accessors for JValueOwned, like .into_bool() instead of .z(), .into_object() instead of .l(), etc (#798)

Fixed

• jni_mangle now includes docs/macros/jni_mangle.md in the crate documentation, so the macro's documentation is visible on docs.rs and in IDEs (#799)

Full Changelog: v0.22.3...v0.22.4

Added

• JCharSequence bindings for java.lang.CharSequence (including AsRef<JCharSequence> + .as_char_sequence() for JString) (#793)
• bind_java_type supports non_null qualifier/property for methods and fields to map null references to Error::NullPtr (#795)
• bind_java_type supports #[cfg()] attributes on methods and fields, to conditionally compile them based on features or other cfg conditions (#797)
• JValueOwned::check_null() + ::is_null() methods for ergonomic null checks on owned (returned) values (#798)
• More readable type accessors for JValueOwned, like .into_bool() instead of .z(), .into_object() instead of .l(), etc (#798)

Fixed

• jni_mangle now includes docs/macros/jni_mangle.md in the crate documentation, so the macro's documentation is visible on docs.rs and in IDEs (#799)

No functional change in this release but it fixes the docs.rs build by bumping the simd_cesu8 dep to >= 1.1.1 which no longer has an automatically-enabled "nightly" feature that may affect the docs.rs build (1.1.x is now also MSRV compatible).

Note: Technically we shouldn't need this release (since the simd_cesu8 release alone will have fixed the build issue) but the other reason for the release is that the crates.io feature for queuing docs.rs rebuilds is not currently usable in our situation. docs.rs is currently fighting through a huge backlog of low-priority build jobs that will likely to take over a week to clear (we moved about 500 spots in two days, out of ~3k crates queued).

Fixed

• docs.rs build: Bumps simd_cesu8 dep to >= 1.1.1 which no longer has an automatically-enabled "nightly" feature that may affect the docs.rs build (1.1.x is now also MSRV compatible) (#790)

Note: although no breaking API change was made in this release there were some important fixes made, including a few non-trivial changes to how exceptions are handled and some important safety / soundness fixes made in the re-exported jni-macros.

For these reasons I'm going to again yank the previous 0.22.1 release after this is published, again taking into account that 0.22.1 was itself only released very recently and it should still be relatively unlikely that anyone has strictly locked in a 0.22.1 dependency.

Another benefit to yanking 0.22.1 is that it allows me to pin the jni-macros dependency via =0.22.2 in this release so that in future releases I don't need to be worried that a new jni-macros release needs to be backwards compatible with all prior jni releases (so macros can take advantage of new jni features).

Hopefully things will be smoother moving forward, now that more people have been starting to update to 0.22.x and there are more people testing it.

Added

Adds bindings for the following java.lang errors / exceptions (#767):

• JArrayIndexOutOfBoundsException (java.lang.ArrayIndexOutOfBoundsException)
• JArrayStoreException (java.lang.ArrayStoreException)
• JClassCircularityError (java.lang.ClassCircularityError)
• JClassFormatError (java.lang.ClassFormatError)
• JExceptionInInitializerError (java.lang.ExceptionInInitializerError)
• JClassNotFoundException (java.lang.ClassNotFoundException)
• JIllegalArgumentException (java.lang.IllegalArgumentException)
• JIllegalMonitorStateException (java.lang.IllegalMonitorStateException)
• JInstantiationException (java.lang.InstantiationException)
• JLinkageError (java.lang.LinkageError)
• JNoClassDefFoundError (java.lang.NoClassDefFoundError)
• JNoSuchFieldError (java.lang.NoSuchFieldError)
• JNoSuchMethodError (java.lang.NoSuchMethodError)
• JNumberFormatException (java.lang.NumberFormatException)
• JOutOfMemoryError (java.lang.OutOfMemoryError)
• JRuntimeException (java.lang.RuntimeException)
• JSecurityException (java.lang.SecurityException)
• JStringIndexOutOfBoundsException (java.lang.StringIndexOutOfBoundsException)

Added AttachmentExceptionPolicy enum to control how Java exceptions are handled when attaching a thread (#768).

Changed

• Replaced cesu8 crate with simd_cesu8 for MUTF-8 encoding, gaining SIMD acceleration and no_std compatibility
• Removed dependency on paste crate (#752)
• attach_current_thread* APIs immediately return Err(JavaException) if a Java exception is pending, so they don't have the side effect of clearing exceptions not thrown in the given closure (#756)
• Removed proc-macro-crate dependency from the jni-macros crate (#758)
• All internal use of JNI functions (not general calls into Java code) now catch exceptions and map to jni::errors::Error (#762)
• JavaVM::attach_current_thread* APIs stash + re-throw pending exceptions so they can be run reliably, instead of bailing early with a JavaException error (e.g. needed in Drop implementations) (#768)

Fixed

• Env::get_[static_]method/field_id APIs now correctly clear + map internal exceptions to Error::Method/FieldNotFound errors (#748)
• Global/Weak::Drop no longer have the side effect of catching/clearing pending exceptions (#749)
• Ensure that the Env::throw* APIs actually return Err(JavaException) as the docs state (#755)
• JStackTraceElement binding fixed to lookup isNativeMethod instead of isNative (#760)
• bind_java_type emits exception_checks before JNI calls to avoid undefined behaviour from calling non-exception-safe JNI functions with pending exceptions. (#757)
• bind_java_type emits env.assert_top() checks to ensure that any new local reference has a lifetime that's associated with the top JNI stack frame (#776)
• Unsound AsRef pointer cast for is_instance_of types emitted by bind_java_type (#777)
• bind_java_type emits null object checks to prevent calling methods or accessing fields on null objects (#781)
• bind_java_type clamps the *API struct and native methods trait visibility to that of the binding type (#785)

New Contributors

• @adityagiri3600 made their first contribution in #742
• @sehnryr made their first contribution in #786

Full Changelog: v0.22.1...v0.22.2

Note: although no breaking API change was made in this release there were some important fixes made, including a few non-trivial changes to how exceptions are handled and some important safety / soundness fixes made in the re-exported jni-macros.

For these reasons I'm going to again yank the previous 0.22.1 release after this is published, again taking into account that 0.22.1 was itself only released very recently and it should still be relatively unlikely that anyone has strictly locked in a 0.22.1 dependency.

Another benefit to yanking 0.22.1 is that it allows me to pin the jni-macros dependency via =0.22.2 in this release so that in future releases I don't need to be worried that a new jni-macros release needs to be backwards compatible with all prior jni releases (so macros can take advantage of new jni features).

Hopefully things will be smoother moving forward, now that more people have been starting to update to 0.22.x and there are more people testing it.

Added

Adds bindings for the following java.lang errors / exceptions (#767):

• JArrayIndexOutOfBoundsException (java.lang.ArrayIndexOutOfBoundsException)
• JArrayStoreException (java.lang.ArrayStoreException)
• JClassCircularityError (java.lang.ClassCircularityError)
• JClassFormatError (java.lang.ClassFormatError)
• JExceptionInInitializerError (java.lang.ExceptionInInitializerError)
• JClassNotFoundException (java.lang.ClassNotFoundException)
• JIllegalArgumentException (java.lang.IllegalArgumentException)
• JIllegalMonitorStateException (java.lang.IllegalMonitorStateException)
• JInstantiationException (java.lang.InstantiationException)
• JLinkageError (java.lang.LinkageError)
• JNoClassDefFoundError (java.lang.NoClassDefFoundError)
• JNoSuchFieldError (java.lang.NoSuchFieldError)
• JNoSuchMethodError (java.lang.NoSuchMethodError)
• JNumberFormatException (java.lang.NumberFormatException)
• JOutOfMemoryError (java.lang.OutOfMemoryError)
• JRuntimeException (java.lang.RuntimeException)
• JSecurityException (java.lang.SecurityException)
• JStringIndexOutOfBoundsException (java.lang.StringIndexOutOfBoundsException)

Added AttachmentExceptionPolicy enum to control how Java exceptions are handled when attaching a thread (#768).

Changed

• Replaced cesu8 crate with simd_cesu8 for MUTF-8 encoding, gaining SIMD acceleration and no_std compatibility
• Removed dependency on paste crate (#752)
• attach_current_thread* APIs immediately return Err(JavaException) if a Java exception is pending, so they don't have the side effect of clearing exceptions not thrown in the given closure (#756)
• Removed proc-macro-crate dependency from the jni-macros crate (#758)
• All internal use of JNI functions (not general calls into Java code) now catch exceptions and map to jni::errors::Error (#762)
• JavaVM::attach_current_thread* APIs stash + re-throw pending exceptions so they can be run reliably, instead of bailing early with a JavaException error (e.g. needed in Drop implementations) (#768)

Fixed

• Env::get_[static_]method/field_id APIs now correctly clear + map internal exceptions to Error::Method/FieldNotFound errors (#748)
• Global/Weak::Drop no longer have the side effect of catching/clearing pending exceptions (#749)
• Ensure that the Env::throw* APIs actually return Err(JavaException) as the docs state (#755)
• JStackTraceElement binding fixed to lookup isNativeMethod instead of isNative (#760)
• bind_java_type emits exception_checks before JNI calls to avoid undefined behaviour from calling non-exception-safe JNI functions with pending exceptions. (#757)
• bind_java_type emits env.assert_top() checks to ensure that any new local reference has a lifetime that's associated with the top JNI stack frame (#776)
• Unsound AsRef pointer cast for is_instance_of types emitted by bind_java_type (#777)
• bind_java_type emits null object checks to prevent calling methods or accessing fields on null objects (#781)
• bind_java_type clamps the *API struct and native methods trait visibility to that of the binding type (#785)

This release fixes several issues found shortly after releasing 0.22.0 which unfortunately required a few breaking changes.

Instead of bumping to 0.23 though, the assumption 🤞 is that no one will yet be depending on the recently-released
0.22.0 and so we can yank that and have this represent the first 0.22.x release.

In particular this addresses the following issues:

• Don't allow JNI calls with pending exceptions (undefined behaviour) #731
• JavaVM::attach_current_thread* should catch + clear exceptions #732
• Env::throw* APIs should return Err(Error::JavaException) #737

Added

• Env::exception_catch provides a convenient way of catching pending Java exceptions and mapping them to Error::CaughtJavaException (#736)
• AttachGuard::detach_with_catch lets you explicitly detach/drop a guard (like ::detach()) and catch any pending Java exception as a Error::CaughtJavaException (#736).
• JClass::get_name lets you query the binary name for a class, such as java.lang.String (#736)

Changed

The following APIs have had to be made fallible again, in order to safely check for pending exceptions before calling
JNI functions that are not documented as being safe to call with a pending exception:

• Env::get_java_vm (GetJavaVM is not exception safe)
• Env::version (GetVersion is not exception safe)
• Env::is_same_object (IsSameObject is not exception safe)
• Weak::is_garbage_collected (based on Env::is_same_object)
• Weak::is_same_object (deprecated) and (based on
  Env::is_same_object)
• Weak::is_weak_ref_to_same_object (deprecated) (based on
  Env::is_same_object)

Note: These are a breaking change.

Fixed in #733

• JavaVM::attach_current_thread* APIs all finish by calling AttachGuard::detach_with_catch to clear pending Java exceptions - mapping to Error::CaughtJavaException (#736)
• Env::throw* APIs now return Error::JavaException after throwing and creating a pending exception that must be handled before using JNI further (#738)

Note: This release fixes several issues found in 0.22.0 which unfortunately required a few breaking changes. Instead of bumping to 0.23 though, the assumption is that no one will yet be depending on the recently-released 0.22.0 and so we can yank that and have this represent the first 0.22.x release.

Added

• Env::exception_catch provides a convenient way of catching pending Java exceptions and mapping them to Error::CaughtJavaException (#736)
• AttachGuard::detach_with_catch lets you explicitly detach/drop a guard (like ::detach()) and catch any pending Java exception as a Error::CaughtJavaException (#736).
• JClass::get_name lets you query the binary name for a class, such as java.lang.String (#736)

Changed

The following APIs have had to be made fallible again, in order to safely check for pending exceptions before calling JNI functions that are not documented as being safe to call with a pending exception:

• Env::get_java_vm (GetJavaVM is not exception safe)
• Env::version (GetVersion is not exception safe)
• Env::is_same_object (IsSameObject is not exception safe)
• Weak::is_garbage_collected (based on Env::is_same_object)
• Weak::is_same_object (deprecated) and (based on Env::is_same_object)
• Weak::is_weak_ref_to_same_object (deprecated) (based on Env::is_same_object)

Note: These are a breaking change.

Fixed in #733

• JavaVM::attach_current_thread* APIs all finish by calling AttachGuard::detach_with_catch to clear pending Java exceptions - mapping to Error::CaughtJavaException (#736)
• Env::throw* APIs now return Error::JavaException after throwing and creating a pending exception that must be handled before using JNI further (#738)

The 0.22 release significantly improves safety and ergonomics through changes to thread attachment, environment handling, and the addition of compile-time macros for JNI strings, signatures as well as full Java type bindings.

Please see the jni 0.22 Migration Guide for guidance on how to update from jni 0.21

Added

JavaVM / Thread Attachment APIs

• JavaVM::singleton() lets you acquire the JavaVM for the process when you know that the JavaVM singleton has been initialized (#595)
• JavaVM::is_thread_attached can query whether the current thread is attached to the Java VM (#570)
• AttachGuard::from_unowned added as a low-level (unsafe) way to represent a thread attachment with a raw jni_sys::Env pointer (#570)
• AttachConfig exposes fine-grained control over thread attachment including Thread name, ThreadGroup and whether scoped or permanent. (#606)
• JavaVM::attach_current_thread_guard is a low-level (unsafe) building block for attaching threads that exposes the AttachGuard and AttachConfig control. (#606)
• JavaVM::attach_current_thread_with_config is a safe building block for attaching threads that hides the AttachGuard but exposes AttachConfig control. (#606)
• JavaVM::with_local_frame added as method to borrow a Env that is already attached to the current thread, after pushing a new JNI stack frame (#570, #673)
• JavaVM::with_top_local_frame_frame added to borrow a Env for the top JNI stack frame (i.e. without pushing a new JNI stack frame) (#570, #673)

Reference Type APIs

• A Reference trait for all reference types like JObject, JClass, JString, enabling Global and Weak to be generic over Reference and enabling safe casting and global caching of JClass references. (#596)
• Reference::lookup_class exposes a cached Global<JClass> for all Reference implementations (#612)
• LoaderContext + LoaderContext::load_class for loading classes, depending on available context (#612)
• Env::new_cast_global_ref acts like new_global_ref with a type cast (#612)
• Env::cast_global takes an owned Global<From> and returns an owned Global<To> (#612)
• Env::new_cast_local_ref acts like new_local_ref with a type cast (#612)
• Env::cast_local takes an owned local reference and returns a new type-cast wrapper (owned) (#612)
• Env::as_cast or Cast::new borrows any From: Reference (global or local) reference and returns a Cast<To> that will Deref into &To (#612)
• Env::as_cast_unchecked returns a Cast<To> like as_cast() but without a runtime IsInstanceOf check (#669)
• Env::as_cast_raw or Cast::from_raw borrows a raw jobject reference and returns a Cast<To> that will Deref into &To
• Cast::new_unchecked and Cast::from_raw_unchecked let you borrow a reference with an (unsafe) type cast, with no runtime check
• ::cast_local() methods as a convenience for all reference types, such as let s = JString::cast_local(obj)
• const null() methods for all reference types.
• Global::null() and Weak::null() construct null references (equivalent to Default::default()). (#596)

JNI Environment APIs

• Env::call_nonvirtual_method and Env::call_nonvirtual_method_unchecked to call non-virtual method. (#454)
• Env::to_reflected_method and Env::to_reflected_static_method for retrieving the Java reflection API instance for a method or constructor. (#579)
• Env::throw_new_void provides an easy way to throw an exception that's constructed with no message argument
• Env::new_object_type_array<E> lets you you instantiate a JObjectArray with a given element type like new_object_type_array::<JString>
• Env::load_class supports class lookups via the current Thread context class loader, with FindClass fallback. (#674)
• MethodSignature and FieldSignature types have been added for compile-time parsed JNI method and field signatures

Native Method APIs

• EnvUnowned is an FFI-safe type that can be used to capture a jni_sys::Env pointer given to native methods and give it a named lifetime (this can then be temporarily upgraded to a &mut Env reference via EnvUnowned::with_env) (#570)
• Outcome is like a Result with the addition of a third Panic() variant, used for careful handling of errors in native methods. (#664)
• EnvOutcome represents an EnvUnowned::with_env outcome whose errors can be handle, with access to JNI, via an ErrorPolicy. (#664)
• ErrorPolicy is a trait with on_error and on_panic methods that can log native method errors or throw them as exceptions. (#664)
• ThrowRuntimeExAndDefault is an ErrorPolicy that throws any error as a RuntimeException (and returns a default value). (#664)
• LogErrorAndDefault is an ErrorPolicy that logs errors and returns a default value. (#664)
• LogContextErrorAndDefault is an ErrorPolicy that logs errors, with a given context string, and returns a default value. (#664)

String APIs

• New functions for converting Rust char to and from Java char and int (#427 / #434)

• JavaStr/MUTF8Chars, JNIStr, and JNIString have several new methods and traits, most notably a to_str method that converts to a regular Rust string. (#510 / #512)

• JNIStr now implements Debug, PartialEq, Eq, PartialOrd, Ord and Hash (#615)

• JNIString now implements Debug, PartialEq, Eq, PartialOrd, Ord, Hash and Clone (#615)

• PartialEq<&JNIStr> for JNIString allows JNIStr and JNIString to be compared. (#615)

• From<&JNIStr> and From<MUTF8Chars> implementations for JNIString. (#615)

• JNIStr::from_cstr safely does a zero-copy cast of a CStr to a JNIStr after a const modified-utf8 encoding validation (#615,#617, #715)

• JNIStr::to_bytes gives access to a &[u8] slice over the bytes of a JNI string (like CStr::to_bytes) (#615)

java.lang APIs

• JClassLoader as a Reference wrapper for java.lang.ClassLoader references (#612)
• JCollection, JSet and JIterator reference wrappers for java.util.Collection, java.util.Set and java.util.Iterator interfaces. (#621)
• JList::remove_item for removing a given value, by-reference, from the list (instead of by index). (#713)
• JList::clear allows a list to be cleared. (#713)
• JList::is_empty checks if a list is empty. (#713)
• JList::as_collection casts a list into a JCollection (#713)
• JObjectArray::new lets you construct a JObjectArray<E> with strong element type parameterization, instead of Env::new_object_array (#657 + #688)
• JObjectArray::get/set_element let you get and set array elements as methods on the array. (#654)
• JPrimitiveArray::new lets you construct a JPrimitiveArray<E>, consistent with JObjectArray::new (#688)
• JStackTraceElement gives access to stack frame info within a stack trace, like filename, line number etc (#657)
• JString now has ::new(), ::from_str and ::from_jni_str constructor methods (#960)
• JThread as a Reference wrapper for java.lang.Thread references (#612)
• JThrowable::get_message is a binding for getMessage() and gives easy access to an exception message
• JThrowable::get_stack_trace is a binding for getStackTrace(), returning a JObjectArray<JStackTraceElement>

Macros

• The #[jni_mangle()] attribute proc macro can export an extern "system" native method with a mangled name like "Java_com_example_myMethod" so it can be automatically resolved within a shared library by the JVM (#693)
• The jni_str! and jni_cstr! macros can encode a MUTF-8 &'static JNIStr or &' static CStr at compile time with full unicode support. (#696)
• The jni_sig!, jni_sig_str!, jni_sig_cstr! and jni_sig_jstr! macros can parse and compile signatures like (arg0: jint, arg1: JString) -> JString into MethodSignature and FieldSignature descriptors or JNI string literals like "(ILjava/lang/String;)Ljava/lang/String;" (#697)
• The native_method! macro binds a single native method to a Rust function with type safety and optionally exports it too. (#698)
• The bind_java_type! macro can generate full Rust bindings for Java types (classes and interfaces) with fields, constructors, methods and native methods (#712)

Changed

JavaVM / Thread Attachment APIs

• JNI version requirements are more explicit in the API and the crate now requires at least JNI >= 1.4. It needs >= 1.2 so it can check for exceptions and needs >= 1.4 to avoid runtime checks for direct byte buffers (#478)
• At a low-level (unsafe), all thread attachments (not just scoped attachments) are now represented by an owned or unowned AttachGuard
• AttachGuard usage is now considered unsafe since the type must be pinned to the stack (but that can't be guaranteed by the Rust type system alone).
• To allow safe thread attachments (that ensure their AttachGuard is pinned to the stack), attachment APIs take a FnOnce whose &mut Env arg borrows from a hidden AttachGuard
  • JavaVM::attach_current_thread requests a permanent thread attachment (reducing cost of future attach_current_thread() calls)
  • JavaVM::attach_current_thread_for_scope requests a thread attachment that's detached after the given closure returns.
• JavaVM::get_java_vm_pointer has been renamed JavaVM::get_raw for consistency.
• JavaVM::new and JavaVM::with_libjvm now prevent libjvm from being unloaded. This isn't necessary for HotSpot, but other JVMs could crash if we don't do this. (#554)

Reference and Primitive Types

• Make from_raw(), into_raw() and null() methods const fn. (#453)

• Make from_raw() require an Env reference so the returned wrapper is guaranteed to have a local reference frame lifetime (#670)

• GlobalRef and WeakRef have been renamed to Global and Weak and are now generic, parameterized, transparent wrappers over 'static reference types like Global<JClass<'static>> (no longer an Arc holding a reference and VM pointer) (#596)

  • Global and Weak no longer implement Clone, since JNI is required to create new reference (you'll need to explicitly use env.new_global_ref)
  • Global and Weak both implement Default, which will represent ::null() references (equivalent to JObject::null())

• Global::into_raw replaces Global::try_into_raw and is infallible (#596)

• AutoLocal has been renamed to Auto with a deprecated type alias for AutoLocal to sign post the rename.

• AutoElements was simplified to only be parameterized by one lifetime for the array reference, and accepts any AsRef<JPrimitiveArray<T>> as a reference. (#508)

• JObjectArray supports generic element types like JObjectArray<JString>

• JavaType was simplified to not capture object names or array details (like ReturnType) since these details don't affect JValue type checks and had a hidden cost that was redundant.

• JValueGen has been removed. JValue and JValueOwned are now separate, unrelated, non-generic types.
  (#429) (Note: previously JValue and JValueOwned were type aliases for
  JValueGen, which was an internal type, but this design led to confusing error messages that made them harder to use)

JNI Environment APIs

• JNIEnv is no longer a #[transparent] FFI-safe pointer wrapper and has been split into EnvUnowned (for FFI/native method args) and Env (non-FFI) (#634)

• A JNIEnv type alias shows a verbose deprecation warning that explains how to migrate from JNIEnv to EnvUnowned and Env (#634)

• Env::get_version has been renamed to Env::version (#478)

• Env is no longer ever exposed in the API by-value can only be accessed by borrowing from a thread attachment AttachGuard.

• Env implements runtime borrow checking to ensure new local references may only be associated with the top JNI stack frame

• JavaVM::get_env is replaced by JavaVM::get_env_attachment which returns an AttachGuard if the current thread is attached. (#570)

• The following functions are now infallible (#478):

  • Env::version
  • Env::get_java_vm
  • Env::exception_check
  • Env::exception_clear
  • Env::exception_describe
  • Env::exception_occurred (#517)
  • Env::is_same_object
  • Env::delete_local_ref
  • WeakRef::is_same_object
  • WeakRef::is_weak_ref_to_same_object
  • WeakRef::is_garbage_collected

• Env::fatal_error is now guaranteed not to panic or allocate, but requires the error message to be encoded ahead of time. (#480)

• Env::get_native_interface has been removed since it's redundant and Env::get_raw is more consistent with other APIs.

• Env::register_native_methods is now marked unsafe since it requires all the given function pointers to be valid and match corresponding Java method signatures (568)

• get_object_class borrows the Env mutably because it creates a new local reference. (#456)

• get/set_*_field_unchecked have been marked as unsafe since they can lead to undefined behaviour if the given types don't match the field type (#457 + #629)

• set_static_field takes a field name and signature as strings so the ID is looked up internally to ensure it's valid. (#629)

• Env::get/set/take_rust_field no longer require a mutable Env reference since they don't return any new local references to the caller (#455)

• Env::get_rust_field returns a MutexGuard<'local> instead of taking the &'env self lifetime (so you don't lose any &mut Env reference you have) (#675)

• Env::is_assignable_from and is_instance_of no longer requires a mutable Env reference, since they don't return any new local references to the caller

• Env::new_weak_ref returns a Result<Weak> and Error::ObjectFreed if the reference is null or has already been freed (instead of Result<Option<Weak>>) (#596)

• Env::new_global_ref and ::new_local_ref may return Error::ObjectFreed in case a weak reference was given and the object has been freed. (#596)

• Env::with_local_frame can be used with a shared &Env reference since it doesn't return a new local reference. (#673)

• Env::with_local_frame_returning_local can now return any kind of local Reference, not just JObject

• Env::new_object_unchecked now takes a Desc<JMethodID> for consistency/flexibility instead of directly taking a JMethodID

String APIs

• JavaStr has been renamed MUTF8Chars (with a deprecated JavaStr alias) and is intended to be got via JString::mutf8_chars()
• JavaStr/MUTF8Chars::from_env has been removed because it was unsound (it could cause undefined behavior and was not marked unsafe). Use JString::mutf8_chars instead. (#510 / #512)
• JavaStr/MUTF8Chars::get_raw has been renamed to as_ptr. (#510 / #512)
• JavaStr/MUTF8Chars, JNIStr, and JNIString no longer coerce to CStr, because using CStr::to_str will often have incorrect results. You can still get a CStr, but must use the new as_cstr method to do so. (#510 / #512)
• All APIs that were accepting modified-utf8 string args via Into<JNIString>, now take AsRef<JNIStr> to avoid string copies every call. Considering that these strings are often literals for signatures or class names, most code can use jni_str!() to encode string literals at compile time, like env.find_class(jni_str!("java/lang/Foo")). (#617, #696)
• JavaStr/MUTF8Chars and JString both implement Display and therefore ToString, making it even easier to get a Rust String.
• Env::get_string performance was optimized by caching an expensive class lookup, and using a faster instanceof check. (#531)
• Env::get_string performance was later further optimized to avoid the need for runtime type checking (#612)
• Env::get_string has been deprecated in favor of JString::mutf8_chars and JString::to_string() or JString::try_to_string(env)

Class Loading APIs

• The documentation for Env::find_class now recommends considering LoaderContext::load_class instead.
• Desc<JClass>::lookup() is now based on LoaderContext::load_class (instead of Env::find_class), which checks for a thread context class loader by default.
• Env::define_class takes a name: Option<> instead of having a separate define_unnamed_class API.
• Env::define_class_bytearray was renamed to Env::define_class_jbyte and is identical to define_class except for taking a &[jbyte] slice instead of &[u8], which is a convenience if you have a JByteArray or AutoElements<JByteArray>.
• Env::define_class[_jbyte] now takes a loader: AsRef<JClassLoader> instead of loader: &JObject.

java.lang APIs

• JList is a simpler, transparent reference wrapper implementing Reference, like JObject, JClass, JString etc
• JList::add returns the boolean returned by the Java API
• JList::get and JList::remove no longer returns an Option since there's nothing special about getting a null from the Java List API.
• JList::pop is deprecated since this doesn't map to standard Java List method.
• JList::iter returns a JIterator instead of a JListIter
• Env::get_list has been deprecated, in favor of JList::cast_local, or other generic Env cast_local/cast_global APIs.
• Env::get_array_elements is deprecated in favor of JPrimitiveArray::get_elements
• Env::get_array_elements_critical is deprecated in favor of JPrimitiveArray::get_elements_critical
• Env::get_*_array_region and Env::set_*_array_region are deprecated in favor of JPrimitiveArray::get/set_region
• Env::get_array_length is deprecated in favor of JPrimitiveArray::len and JObjectArray::len
• Env::get/set_object_array_element are deprecated in favor of JObjectArray::get/set_element
• Env::new_*_array methods for primitive array types (like JByteArray) take a &mut Env and a usize len, and the docs recommend using J<Type>Array::new() instead.

Miscellaneous

• AutoElements[Critical]::discard() now takes ownership of the elements and drops them to release the pointer after setting the mode to NoCopyBack (#645)
• Mark MonitorGuard with #[must_use] to warn when the guard is dropped accidentally (#676)
• NativeMethod (used with Env::register_native_methods) is a now a transparent jni::sys::JNINativeWrapper wrapper with an unsafe ::from_raw_parts constructor.
• All APIs that require a JNI signature (like Env::get_method_id, Env::call_method etc) now require a pre-parsed MethodSignature or FieldSignature type instead of a raw string. This enables compile-time signature parsing via the jni_sig! macro, and avoids runtime signature parsing costs. (#714)

Dependencies

• jni-sys dependency bumped to 0.4 (#478)

Fixed

• Env::get_string no longer leaks local references. (#528, #557)
• Deadlocks on Windows when automatically detaching JNI when threads exit. Attachments are now tracked with fiber local storage so detachment happens without holding OS loader lock. (#701)

Removed

• JavaVM::attach_current_thread_as_daemon (and general support for 'daemon' threads) has been removed, since their semantics are inherently poorly defined and unsafe (the distinction relates to the poorly defined limbo state after calling JavaDestroyVM, where it becomes undefined to touch the JVM) (#593)
• The 'Executor' API has been removed (AttachGuard::with_env can be used instead) (#570)
• Env::from_raw, Env::from_raw_unchecked and Env::unsafe_clone have been removed, since the API no longer exposes the Env type by-value, it must always be borrowed from an AttachGuard. (#570)
• Error::NullDeref and Error::JavaVMMethodNotFound have been removed since they were unused.
• JavaType::Method was removed since a method signature isn't a type, and all usage was being matched as unreachable or an error.
• Env::define_unnamed_class was removed in favor of having the define_class[_jbyte] APIs take a name: Option instead.

New Contributors

• @cakekindel made their first contribution in #445
• @koutheir made their first contribution in #453
• @Rabbit0w0 made their first contribution in #454
• @jerrinot made their first contribution in #490
• @Jake-Shadle made their first contribution in #489
• @tisonkun made their first contribution in #497
• @ssrlive made their first contribution in #559
• @complexspaces made their first contribution in #552
• @olivergillespie made their first contribution in #531
• @emergent made their first contribution in #544
• @elichai made their first contribution in #561
• @akonradi-signal made their first contribution in #579
• @atouchet made their first contribution in #578
• @louwers made their first contribution in #583
• @StDymphna made their first contribution in #618
• @pr2502 made their first contribution in #676
• @moretea made their first contribution in #679

Full Changelog: v0.21.1...v0.22.0

Added

JavaVM / Thread Attachment APIs

• JavaVM::singleton() lets you acquire the JavaVM for the process when you know that the JavaVM singleton has been initialized (#595)
• JavaVM::is_thread_attached can query whether the current thread is attached to the Java VM (#570)
• AttachGuard::from_unowned added as a low-level (unsafe) way to represent a thread attachment with a raw jni_sys::Env pointer (#570)
• AttachConfig exposes fine-grained control over thread attachment including Thread name, ThreadGroup and whether scoped or permanent. (#606)
• JavaVM::attach_current_thread_guard is a low-level (unsafe) building block for attaching threads that exposes the AttachGuard and AttachConfig control. (#606)
• JavaVM::attach_current_thread_with_config is a safe building block for attaching threads that hides the AttachGuard but exposes AttachConfig control. (#606)
• JavaVM::with_local_frame added as method to borrow a Env that is already attached to the current thread, after pushing a new JNI stack frame (#570, #673)
• JavaVM::with_top_local_frame_frame added to borrow a Env for the top JNI stack frame (i.e. without pushing a new JNI stack frame) (#570, #673)

Reference Type APIs

• A Reference trait for all reference types like JObject, JClass, JString, enabling Global and Weak to be generic over Reference and enabling safe casting and global caching of JClass references. (#596)
• Reference::lookup_class exposes a cached Global<JClass> for all Reference implementations (#612)
• LoaderContext + LoaderContext::load_class for loading classes, depending on available context (#612)
• Env::new_cast_global_ref acts like new_global_ref with a type cast (#612)
• Env::cast_global takes an owned Global<From> and returns an owned Global<To> (#612)
• Env::new_cast_local_ref acts like new_local_ref with a type cast (#612)
• Env::cast_local takes an owned local reference and returns a new type-cast wrapper (owned) (#612)
• Env::as_cast or Cast::new borrows any From: Reference (global or local) reference and returns a Cast<To> that will Deref into &To (#612)
• Env::as_cast_unchecked returns a Cast<To> like as_cast() but without a runtime IsInstanceOf check (#669)
• Env::as_cast_raw or Cast::from_raw borrows a raw jobject reference and returns a Cast<To> that will Deref into &To
• Cast::new_unchecked and Cast::from_raw_unchecked let you borrow a reference with an (unsafe) type cast, with no runtime check
• ::cast_local() methods as a convenience for all reference types, such as let s = JString::cast_local(obj)
• const null() methods for all reference types.
• Global::null() and Weak::null() construct null references (equivalent to Default::default()). (#596)

JNI Environment APIs

• Env::call_nonvirtual_method and Env::call_nonvirtual_method_unchecked to call non-virtual method. (#454)
• Env::to_reflected_method and Env::to_reflected_static_method for retrieving the Java reflection API instance for a method or constructor. (#579)
• Env::throw_new_void provides an easy way to throw an exception that's constructed with no message argument
• Env::new_object_type_array<E> lets you you instantiate a JObjectArray with a given element type like new_object_type_array::<JString>
• Env::load_class supports class lookups via the current Thread context class loader, with FindClass fallback. (#674)
• MethodSignature and FieldSignature types have been added for compile-time parsed JNI method and field signatures

Native Method APIs

• EnvUnowned is an FFI-safe type that can be used to capture a jni_sys::Env pointer given to native methods and give it a named lifetime (this can then be temporarily upgraded to a &mut Env reference via EnvUnowned::with_env) (#570)
• Outcome is like a Result with the addition of a third Panic() variant, used for careful handling of errors in native methods. (#664)
• EnvOutcome represents an EnvUnowned::with_env outcome whose errors can be handle, with access to JNI, via an ErrorPolicy. (#664)
• ErrorPolicy is a trait with on_error and on_panic methods that can log native method errors or throw them as exceptions. (#664)
• ThrowRuntimeExAndDefault is an ErrorPolicy that throws any error as a RuntimeException (and returns a default value). (#664)
• LogErrorAndDefault is an ErrorPolicy that logs errors and returns a default value. (#664)
• LogContextErrorAndDefault is an ErrorPolicy that logs errors, with a given context string, and returns a default value. (#664)

String APIs

• New functions for converting Rust char to and from Java char and int (#427 / #434)

• JavaStr/MUTF8Chars, JNIStr, and JNIString have several new methods and traits, most notably a to_str method that converts to a regular Rust string. (#510 / #512)

• JNIStr now implements Debug, PartialEq, Eq, PartialOrd, Ord and Hash (#615)

• JNIString now implements Debug, PartialEq, Eq, PartialOrd, Ord, Hash and Clone (#615)

• PartialEq<&JNIStr> for JNIString allows JNIStr and JNIString to be compared. (#615)

• From<&JNIStr> and From<MUTF8Chars> implementations for JNIString. (#615)

• JNIStr::from_cstr safely does a zero-copy cast of a CStr to a JNIStr after a const modified-utf8 encoding validation (#615,#617, #715)

• JNIStr::to_bytes gives access to a &[u8] slice over the bytes of a JNI string (like CStr::to_bytes) (#615)

java.lang APIs

• JClassLoader as a Reference wrapper for java.lang.ClassLoader references (#612)
• JCollection, JSet and JIterator reference wrappers for java.util.Collection, java.util.Set and java.util.Iterator interfaces. (#621)
• JList::remove_item for removing a given value, by-reference, from the list (instead of by index). (#713)
• JList::clear allows a list to be cleared. (#713)
• JList::is_empty checks if a list is empty. (#713)
• JList::as_collection casts a list into a JCollection (#713)
• JObjectArray::new lets you construct a JObjectArray<E> with strong element type parameterization, instead of Env::new_object_array (#657 + #688)
• JObjectArray::get/set_element let you get and set array elements as methods on the array. (#654)
• JPrimitiveArray::new lets you construct a JPrimitiveArray<E>, consistent with JObjectArray::new (#688)
• JStackTraceElement gives access to stack frame info within a stack trace, like filename, line number etc (#657)
• JString now has ::new(), ::from_str and ::from_jni_str constructor methods (#960)
• JThread as a Reference wrapper for java.lang.Thread references (#612)
• JThrowable::get_message is a binding for getMessage() and gives easy access to an exception message
• JThrowable::get_stack_trace is a binding for getStackTrace(), returning a JObjectArray<JStackTraceElement>

Macros

• The #[jni_mangle()] attribute proc macro can export an extern "system" native method with a mangled name like "Java_com_example_myMethod" so it can be automatically resolved within a shared library by the JVM (#693)
• The jni_str! and jni_cstr! macros can encode a MUTF-8 &'static JNIStr or &' static CStr at compile time with full unicode support. (#696)
• The jni_sig!, jni_sig_str!, jni_sig_cstr! and jni_sig_jstr! macros can parse and compile signatures like (arg0: jint, arg1: JString) -> JString into MethodSignature and FieldSignature descriptors or JNI string literals like "(ILjava/lang/String;)Ljava/lang/String;" (#697)
• The native_method! macro binds a single native method to a Rust function with type safety and optionally exports it too. (#698)
• The bind_java_type! macro can generate full Rust bindings for Java types (classes and interfaces) with fields, constructors, methods and native methods (#712)

Changed

JavaVM / Thread Attachment APIs

• JNI version requirements are more explicit in the API and the crate now requires at least JNI >= 1.4. It needs >= 1.2 so it can check for exceptions and needs >= 1.4 to avoid runtime checks for direct byte buffers (#478)
• At a low-level (unsafe), all thread attachments (not just scoped attachments) are now represented by an owned or unowned AttachGuard
• AttachGuard usage is now considered unsafe since the type must be pinned to the stack (but that can't be guaranteed by the Rust type system alone).
• To allow safe thread attachments (that ensure their AttachGuard is pinned to the stack), attachment APIs take a FnOnce whose &mut Env arg borrows from a hidden AttachGuard
  • JavaVM::attach_current_thread requests a permanent thread attachment (reducing cost of future attach_current_thread() calls)
  • JavaVM::attach_current_thread_for_scope requests a thread attachment that's detached after the given closure returns.
• JavaVM::get_java_vm_pointer has been renamed JavaVM::get_raw for consistency.
• JavaVM::new and JavaVM::with_libjvm now prevent libjvm from being unloaded. This isn't necessary for HotSpot, but other JVMs could crash if we don't do this. (#554)

Reference and Primitive Types

• Make from_raw(), into_raw() and null() methods const fn. (#453)

• Make from_raw() require an Env reference so the returned wrapper is guaranteed to have a local reference frame lifetime (#670)

• GlobalRef and WeakRef have been renamed to Global and Weak and are now generic, parameterized, transparent wrappers over 'static reference types like Global<JClass<'static>> (no longer an Arc holding a reference and VM pointer) (#596)

  • Global and Weak no longer implement Clone, since JNI is required to create new reference (you'll need to explicitly use env.new_global_ref)
  • Global and Weak both implement Default, which will represent ::null() references (equivalent to JObject::null())

• Global::into_raw replaces Global::try_into_raw and is infallible (#596)

• AutoLocal has been renamed to Auto with a deprecated type alias for AutoLocal to sign post the rename.

• AutoElements was simplified to only be parameterized by one lifetime for the array reference, and accepts any AsRef<JPrimitiveArray<T>> as a reference. (#508)

• JObjectArray supports generic element types like JObjectArray<JString>

• JavaType was simplified to not capture object names or array details (like ReturnType) since these details don't affect JValue type checks and had a hidden cost that was redundant.

• JValueGen has been removed. JValue and JValueOwned are now separate, unrelated, non-generic types. (#429) (Note: previously JValue and JValueOwned were type aliases for JValueGen, which was an internal type, but this design led to confusing error messages that made them harder to use)

JNI Environment APIs

• JNIEnv is no longer a #[transparent] FFI-safe pointer wrapper and has been split into EnvUnowned (for FFI/native method args) and Env (non-FFI) (#634)

• A JNIEnv type alias shows a verbose deprecation warning that explains how to migrate from JNIEnv to EnvUnowned and Env (#634)

• Env::get_version has been renamed to Env::version (#478)

• Env is no longer ever exposed in the API by-value can only be accessed by borrowing from a thread attachment AttachGuard.

• Env implements runtime borrow checking to ensure new local references may only be associated with the top JNI stack frame

• JavaVM::get_env is replaced by JavaVM::get_env_attachment which returns an AttachGuard if the current thread is attached. (#570)

• The following functions are now infallible (#478):

  • Env::version
  • Env::get_java_vm
  • Env::exception_check
  • Env::exception_clear
  • Env::exception_describe
  • Env::exception_occurred (#517)
  • Env::is_same_object
  • Env::delete_local_ref
  • WeakRef::is_same_object
  • WeakRef::is_weak_ref_to_same_object
  • WeakRef::is_garbage_collected

• Env::fatal_error is now guaranteed not to panic or allocate, but requires the error message to be encoded ahead of time. (#480)

• Env::get_native_interface has been removed since it's redundant and Env::get_raw is more consistent with other APIs.

• Env::register_native_methods is now marked unsafe since it requires all the given function pointers to be valid and match corresponding Java method signatures (568)

• get_object_class borrows the Env mutably because it creates a new local reference. (#456)

• get/set_*_field_unchecked have been marked as unsafe since they can lead to undefined behaviour if the given types don't match the field type (#457 + #629)

• set_static_field takes a field name and signature as strings so the ID is looked up internally to ensure it's valid. (#629)

• Env::get/set/take_rust_field no longer require a mutable Env reference since they don't return any new local references to the caller (#455)

• Env::get_rust_field returns a MutexGuard<'local> instead of taking the &'env self lifetime (so you don't lose any &mut Env reference you have) (#675)

• Env::is_assignable_from and is_instance_of no longer requires a mutable Env reference, since they don't return any new local references to the caller

• Env::new_weak_ref returns a Result<Weak> and Error::ObjectFreed if the reference is null or has already been freed (instead of Result<Option<Weak>>) (#596)

• Env::new_global_ref and ::new_local_ref may return Error::ObjectFreed in case a weak reference was given and the object has been freed. (#596)

• Env::with_local_frame can be used with a shared &Env reference since it doesn't return a new local reference. (#673)

• Env::with_local_frame_returning_local can now return any kind of local Reference, not just JObject

• Env::new_object_unchecked now takes a Desc<JMethodID> for consistency/flexibility instead of directly taking a JMethodID

String APIs

• JavaStr has been renamed MUTF8Chars (with a deprecated JavaStr alias) and is intended to be got via JString::mutf8_chars()
• JavaStr/MUTF8Chars::from_env has been removed because it was unsound (it could cause undefined behavior and was not marked unsafe). Use JString::mutf8_chars instead. (#510 / #512)
• JavaStr/MUTF8Chars::get_raw has been renamed to as_ptr. (#510 / #512)
• JavaStr/MUTF8Chars, JNIStr, and JNIString no longer coerce to CStr, because using CStr::to_str will often have incorrect results. You can still get a CStr, but must use the new as_cstr method to do so. (#510 / #512)
• All APIs that were accepting modified-utf8 string args via Into<JNIString>, now take AsRef<JNIStr> to avoid string copies every call. Considering that these strings are often literals for signatures or class names, most code can use jni_str!() to encode string literals at compile time, like env.find_class(jni_str!("java/lang/Foo")). (#617, #696)
• JavaStr/MUTF8Chars and JString both implement Display and therefore ToString, making it even easier to get a Rust String.
• Env::get_string performance was optimized by caching an expensive class lookup, and using a faster instanceof check. (#531)
• Env::get_string performance was later further optimized to avoid the need for runtime type checking (#612)
• Env::get_string has been deprecated in favor of JString::mutf8_chars and JString::to_string() or JString::try_to_string(env)

Class Loading APIs

• The documentation for Env::find_class now recommends considering LoaderContext::load_class instead.
• Desc<JClass>::lookup() is now based on LoaderContext::load_class (instead of Env::find_class), which checks for a thread context class loader by default.
• Env::define_class takes a name: Option<> instead of having a separate define_unnamed_class API.
• Env::define_class_bytearray was renamed to Env::define_class_jbyte and is identical to define_class except for taking a &[jbyte] slice instead of &[u8], which is a convenience if you have a JByteArray or AutoElements<JByteArray>.
• Env::define_class[_jbyte] now takes a loader: AsRef<JClassLoader> instead of loader: &JObject.

java.lang APIs

• JList is a simpler, transparent reference wrapper implementing Reference, like JObject, JClass, JString etc
• JList::add returns the boolean returned by the Java API
• JList::get and JList::remove no longer returns an Option since there's nothing special about getting a null from the Java List API.
• JList::pop is deprecated since this doesn't map to standard Java List method.
• JList::iter returns a JIterator instead of a JListIter
• Env::get_list has been deprecated, in favor of JList::cast_local, or other generic Env cast_local/cast_global APIs.
• Env::get_array_elements is deprecated in favor of JPrimitiveArray::get_elements
• Env::get_array_elements_critical is deprecated in favor of JPrimitiveArray::get_elements_critical
• Env::get_*_array_region and Env::set_*_array_region are deprecated in favor of JPrimitiveArray::get/set_region
• Env::get_array_length is deprecated in favor of JPrimitiveArray::len and JObjectArray::len
• Env::get/set_object_array_element are deprecated in favor of JObjectArray::get/set_element
• Env::new_*_array methods for primitive array types (like JByteArray) take a &mut Env and a usize len, and the docs recommend using J<Type>Array::new() instead.

Miscellaneous

• AutoElements[Critical]::discard() now takes ownership of the elements and drops them to release the pointer after setting the mode to NoCopyBack (#645)
• Mark MonitorGuard with #[must_use] to warn when the guard is dropped accidentally (#676)
• NativeMethod (used with Env::register_native_methods) is a now a transparent jni::sys::JNINativeWrapper wrapper with an unsafe ::from_raw_parts constructor.
• All APIs that require a JNI signature (like Env::get_method_id, Env::call_method etc) now require a pre-parsed MethodSignature or FieldSignature type instead of a raw string. This enables compile-time signature parsing via the jni_sig! macro, and avoids runtime signature parsing costs. (#714)

Dependencies

• jni-sys dependency bumped to 0.4 (#478)

Fixed

• Env::get_string no longer leaks local references. (#528, #557)
• Deadlocks on Windows when automatically detaching JNI when threads exit. Attachments are now tracked with fiber local storage so detachment happens without holding OS loader lock. (#701)

Removed

• JavaVM::attach_current_thread_as_daemon (and general support for 'daemon' threads) has been removed, since their semantics are inherently poorly defined and unsafe (the distinction relates to the poorly defined limbo state after calling JavaDestroyVM, where it becomes undefined to touch the JVM) (#593)
• The 'Executor' API has been removed (AttachGuard::with_env can be used instead) (#570)
• Env::from_raw, Env::from_raw_unchecked and Env::unsafe_clone have been removed, since the API no longer exposes the Env type by-value, it must always be borrowed from an AttachGuard. (#570)
• Error::NullDeref and Error::JavaVMMethodNotFound have been removed since they were unused.
• JavaType::Method was removed since a method signature isn't a type, and all usage was being matched as unreachable or an error.
• Env::define_unnamed_class was removed in favor of having the define_class[_jbyte] APIs take a name: Option instead.

Fixes

• Compilation is fixed for architectures with a C ABI that has unsigned char types. (#419)
• JNIEnv::get_string no longer leaks local references. (#528)

This release makes extensive breaking changes in order to improve safety. Most projects that use this library will need to be changed. Please see the migration guide.

Added

• JavaStr::into_raw() which drops the JavaStr and releases ownership of the raw string pointer (#374)
• JavaStr::from_raw() which takes ownership of a raw string pointer to create a JavaStr (#374)
• JNIEnv::get_string_unchecked is a cheaper, unsafe alternative to get_string that doesn't check the given object is a java.lang.String instance. (#328)
• WeakRef and JNIEnv#new_weak_ref. (#304)
• define_class_bytearray method that takes an AutoElements<jbyte> rather than a &[u8] (#244)
• JObject now has an as_raw method that borrows the JObject instead of taking ownership like into_raw. Needed because JObject no longer has the Copy trait. (#392)
• JavaVM::destroy() (unsafe) as a way to try and unload a JavaVM on supported platforms (#391)
• JavaVM::detach_current_thread() (unsafe) as a way to explicitly detach a thread (normally this is automatic on thread exit). Needed to detach daemon threads manually if using JavaVM::destroy() (#391)
• JPrimitiveArray<T: TypeArray> and type-specific aliases like JByteArray, JIntArray etc now provide safe, reference wrappers for the sys types jarray and jbyteArray etc with a lifetime like JObject (#400)
• JObjectArray provides a reference wrapper for a jobjectArray with a lifetime like JObject. (#400)
• AutoElements and AutoElementsCritical (previously AutoArray/AutoPrimitiveArray) implement Deref<Target=[T]> and DerefMut so array elements can be accessed via slices without needing additional unsafe code. (#400)
• AsJArrayRaw trait which enables JNIEnv::get_array_length() to work with JPrimitiveArray or JObjectArray types (#400)
• InitArgsBuilder now has try_option and option_encoded methods. (#414)

Changed

• JNIEnv::get_string checks that the given object is a java.lang.String instance to avoid undefined behaviour from the JNI implementation potentially aborting the program. (#328)
• JNIEnv::call_*method_unchecked was marked unsafe, as passing improper argument types, or a bad number of arguments, can cause a JVM crash. (#385)
• The JNIEnv::new_object_unchecked function now takes arguments as &[jni::sys::jvalue] to avoid allocating, putting it inline with changes to JniEnv::call_*_unchecked from 0.20.0 (#382)
• The get_superclass function now returns an Option instead of a null pointer if the class has no superclass (#151)
• The invocation feature now locates the JVM implementation dynamically at runtime (via the java-locator crate by default) instead of linking with the JVM at build time (#293)
• Most JNIEnv methods now require &mut self. This improves safety by preventing JObjects from getting an invalid lifetime. Most native method implementations (that is, #[no_mangle] extern "system" fns) must now make the JNIEnv parameter mut. See the example on the crate documentation. (#392)
• JByteBuffer, JClass, JNIEnv, JObject, JString, and JThrowable no longer have the Clone or Copy traits. This improves safety by preventing object references from being used after the JVM deletes them. Most functions that take one of these types as a parameter (except extern fns that are directly called by the JVM) should now borrow it instead, e.g. &JObject instead of JObject. (#392)
• AutoLocal is now generic in the type of object reference (JString, etc). (#392)
• The closure passed to JNIEnv::with_local_frame must now take a &mut JNIEnv parameter, which has a different lifetime. This improves safety by preventing local references from escaping the closure, which would cause a use-after-free bug. Executor::with_attached and Executor::with_attached_capacity have been similarly changed. (#392)
• The closure passed to JNIEnv::with_local_frame can now return a generic Result<T, E> so long as the error implements From<jni::errors::Error> (#399)
• JNIEnv::with_local_frame now returns the same type that the given closure returns (#399)
• JNIEnv::with_local_frame no longer supports returning a local reference directly to the calling scope (see with_local_frame_returning_local) (#399)
• Executor::with_attached and Executor::with_attached_capacity have been changed in the same way as JNIEnv::with_local_frame (they are thin wrappers) (#399)
• Desc, JNIEnv::pop_local_frame, and TypeArray are now unsafe. (#392)
• The Desc trait now has an associated type Output. Many implementations now return AutoLocal, so if you call Desc::lookup yourself and then call as_raw on the returned object, make sure the AutoLocal isn't dropped too soon (see the Desc::lookup documentation for examples). (#392)
• The Desc<JClass> trait is no longer implemented for JObject or &JObject. The previous implementation that called .get_object_class() was surprising and a simpler cast would make it easy to mistakenly pass instances where a class is required. (#118)
• Named lifetimes in the documentation have more descriptive names (like 'local instead of 'a). The new naming convention is explained in the JNIEnv documentation. (#392)
• Object reference types (JObject, JClass, AutoLocal, GlobalRef, etc) now implement AsRef<JObject> and Deref<Target = JObject>. Typed wrappers like JClass also implement Into<JObject>, but GlobalRef does not. (#392)
• Most JList and JMap methods now require a &mut JNIEnv parameter. JListIter and JMapIter no longer implement Iterator, and instead have a next method that requires a &mut JNIEnv parameter (use while let loops instead of for). (#392)
• JValue has been changed in several ways: (#392)
  • It is now a generic type named JValueGen. JValue is now a type alias for JValueGen<&JObject>, that is, it borrows an object reference. JValueOwned is a type alias for JValueGen<JObject>, that is, it owns an object reference.
  • JValueOwned does not have the Copy trait.
  • The to_jni method is now named as_jni, and it borrows the JValueGen instead of taking ownership.
  • JObject can no longer be converted directly to JValue, which was commonly done when calling Java methods or constructors. Instead of obj.into(), use (&obj).into().
• All JNIEnv array APIs now work in terms of JPrimitiveArray and JObjectArray (reference wrappers with a lifetime) instead of sys types like jarray and jbyteArray (#400)
• AutoArray and AutoPrimitiveArray have been renamed AutoElements and AutoElementsCritical to show their connection and differentiate from new JPrimitiveArray API (#400)
• get_primitive_array_critical is now unsafe and has been renamed to get_array_elements_critical (consistent with the rename of AutoPrimitiveArray) with more detailed safety documentation (#400)
• get_array_elements is now also unsafe (for many of the same reasons as get_array_elements_critical) and has detailed safety documentation (#400)
• AutoArray/AutoArrayCritical::size() has been replaced with .len() which can't fail and returns a usize (#400)
• The TypeArray trait is now a private / sealed trait, that is considered to be an implementation detail for the AutoArray API.
• JvmError has several more variants and is now non_exhaustive. (#414)
• InitArgsBuilder::option raises an error on Windows if the string is too long. The limit is currently 1048576 bytes. (#414)

Fixed

• Trying to use an object reference after it has been deleted now causes a compile error instead of undefined behavior. As a result, it is now safe to use AutoLocal, JNIEnv::delete_local_ref, and JNIEnv::with_local_frame. (Most of the limitations added in #392, listed above, were needed to make this work.) (#381, #392)
• Class lookups via the Desc trait now return AutoLocals, which prevents them from leaking. (#109, #392)
• InitArgsBuilder::option properly encodes non-ASCII characters on Windows. (#414)

Removed

• get_string_utf_chars and release_string_utf_chars from JNIEnv (See JavaStr::into_raw() and JavaStr::from_raw() instead) (#372)
• All JNIEnv::get_<type>_array_elements() methods have been removed as redundant since they would all be equivalent to get_array_elements() with the introduction of JPrimitiveArray (#400)

Added

• Default trait implemented for JObject, JString, JClass, and JByteBuffer (#199)
• Debug trait implemented for JavaVM, GlobalRef, GlobalRefGuard, JStaticMethodID and ReleaseMode (#345)
• ReturnType for specifying object return types without a String allocation. (#329)

Changed

• The release_string_utf_chars function has been marked as unsafe. (#334)
• Mark JNIEnv::new_direct_byte_buffer as unsafe (#320)
• JNIEnv::new_direct_byte_buffer now takes a raw pointer and size instead of a slice (#351 and #364)
• JNIEnv::direct_buffer_address returns a raw pointer instead of a slice (#364)
• The lifetime of AutoArray is no longer tied to the lifetime of a particular JNIEnv reference. (#302)
• Relaxed lifetime restrictions on JNIEnv::new_local_ref. Now it can be used to create a local reference from a global reference. (#301 / #319)
• JMethodID and JStaticMethodID implement Send + Sync and no longer has a lifetime parameter, making method IDs cacheable (with a documented 'Safety' note about ensuring they remain valid). (#346)
• JFieldID and JStaticFieldID implement Send + Sync and no longer has a lifetime parameter, making field IDs cacheable (with a documented 'Safety' note about ensuring they remain valid). (#346)
• The call_*_method_unchecked functions now take jni:sys::jvalue arguments to avoid allocating a Vec on each call to map + collect JValues as sys:jvalues (#329)
• The From trait implementations converting jni_sys types like jobject to JObject have been replaced with unsafe ::from_raw functions and corresponding ::into_raw methods. Existing ::into_inner APIs were renamed ::into_raw for symmetry. (#197)
• The APIs JNIEnv::set_rust_field, JNIEnv::get_rust_field and JNIEnv::take_rust_field have been marked as unsafe (#219)

Added

• AutoArray and generic get_array_elements(), along with get_<type>_array_elements helpers. (#287)
• size() method to AutoArray and AutoPrimitiveArray. (#278 / #287)
• discard() method to AutoArray and AutoPrimitiveArray. (#275 / #287)

Changed

• Removed AutoPrimitiveArray::commit(). (#290)
• AutoByte/PrimitiveArray.commit() now returns Result. (#275)
• Removed methods get/release/commit_byte/primitive_array_{elements|critical}. (#281)
• Renamed methods get_auto_byte/long/primitive_array_{elements|critical} to get_byte/long/primitive_array_{elements|critical}. (#281)

Added

• JNIEnv#define_unnamed_class function that allows loading a class without specifying its name. The name is inferred from the class data. (#246)
• SetStatic<type>Field. (#248)
• TryFrom<JValue> for types inside JValue variants (#264).
• Implemented Copy for JNIEnv (#255).
• repr(transparent) attribute to JavaVM struct (#259)

Changed

• Switch from error-chain to thiserror, making all errors Send. Also, support all JNI errors in the jni_error_code_to_result function and add more information to the InvalidArgList error. (#242)

Added

• Get/ReleaseByteArrayElements, and Get/ReleasePrimitiveArrayCritical. (#237)

Fixed

• Java VM instantiation with some MacOS configurations. (#220, #229, #230).

Added

• Ability to pass object wrappers that are convertible to JObject as arguments to the majority of JNIEnv methods without explicit conversion. (#213)
• JNIEnv#is_same_object implementation. (#213)
• JNIEnv#register_native_methods. (#214)
• Conversion from Into<JObject> to JValue::Object.

Fixed

• Passing null as class loader to define_class method now allowed according to the JNI specification. (#225)

Changed

• Relaxed some lifetime restrictions in JNIEnv to support the case when method, field ids; and global references to classes have a different (larger) lifetime than JNIEnv. (#209)

Changed

• Various documentation improvements.

0.13 brings major improvements in thread management, allowing to attach the native threads permanently and safely; Executor for extra convenience and safety; and other improvements and fixes.

:warning: If your code attaches native threads — make sure to check the updated documentation of JavaVM to learn about the new features!

Added

• JavaVM::attach_current_thread_permanently method, which attaches the current thread and detaches it when the thread finishes. Daemon threads attached with JavaVM::attach_current_thread_as_daemon also automatically detach themselves when finished. The number of currently attached threads may be acquired using JavaVM::threads_attached method. (#179, #180)
• Executor — a simple thread attachment manager which helps to safely execute a closure in attached thread context and to automatically free created local references at closure exit. (#186)

Changed

• The default JNI API version in InitArgsBuilder from V1 to V8. (#178)
• Extended the lifetimes of AutoLocal to make it more flexible. (#190)
• Default exception type from checked java.lang.Exception to unchecked java.lang.RuntimeException. It is used implicitly when JNIEnv#throw is invoked with exception message: env.throw("Exception message"); however, for efficiency reasons, it is recommended to specify the exception type explicitly and use throw_new: env.throw_new(exception_type, "Exception message"). (#194)

Fixed

• Native threads attached with JavaVM::attach_current_thread_as_daemon now automatically detach themselves on exit, preventing Java Thread leaks. (#179)
• Local reference leaks in JList, JMap and JMapIter. (#190, #191)