Struct jni::objects::GlobalRef

pub struct GlobalRef { /* fields omitted */ }

A global JVM reference. These are "pinned" by the garbage collector and are guaranteed to not get collected until released. Thus, this is allowed to outlive the JNIEnv that it came from and can be used in other threads.

GlobalRef can be cloned to use the same global reference in different contexts. If you want to create yet another global ref to the same java object you may call JNIEnv#new_global_ref just like you do when create GlobalRef from a local reference.

Underlying global reference will be dropped, when the last instance of GlobalRef leaves its scope.

It is recommended that a native thread that drops the global reference is attached to the Java thread (i.e., has an instance of JNIEnv). If the native thread is not attached, the GlobalRef#drop will print a warning and implicitly attach and detach it, which significantly affects performance.

Methods

impl GlobalRef

pub unsafe fn from_raw(vm: JavaVM, obj: jobject) -> Self

Creates a new global reference. This assumes that NewGlobalRef has already been called.

pub fn as_obj<'a>(&'a self) -> JObject<'a>

Get the object from the global ref

This borrows the ref and prevents it from being dropped as long as the JObject sticks around.

Trait Implementations

impl<'a, 'b> Desc<'a, JClass<'b>> for &'b GlobalRef

This conversion assumes that the GlobalRef is a pointer to a class object.

fn lookup(self, _: &JNIEnv<'a>) -> Result<JClass<'b>>

Look up the concrete type from the JVM.

impl Clone for GlobalRef

fn clone(&self) -> GlobalRef

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Send for GlobalRef

impl<'a> From<&'a GlobalRef> for JObject<'a>

fn from(other: &'a GlobalRef) -> JObject<'a>

Performs the conversion.