Struct JavaVM

pub struct JavaVM { /* private fields */ }

A struct for interacting with the Java VM.

JNI documentation

Examples

use rust_jni::{InitArguments, JavaVM, JniVersion, JvmOption, JvmVerboseOption};
use std::ptr;

let options = InitArguments::get_default(JniVersion::V8).unwrap()
    .with_option(JvmOption::Verbose(JvmVerboseOption::Gc))
    .with_option(JvmOption::Verbose(JvmVerboseOption::Jni));

let vm = JavaVM::create(&options).unwrap();
unsafe {
    assert_ne!(vm.raw_jvm(), ptr::null_mut());
}

let vms = JavaVM::list().unwrap();
unsafe {
    assert_eq!(vms[0].raw_jvm(), vm.raw_jvm());
}

JavaVM is Send + Sync. It means it can be shared between threads.

use rust_jni::{InitArguments, JavaVM, JniVersion};
use std::ptr;
use std::sync::Arc;

let vm =
    Arc::new(JavaVM::create(&InitArguments::get_default(JniVersion::V8).unwrap()).unwrap());
{
    let vm = vm.clone();
    ::std::thread::spawn(move || {
        unsafe {
            assert_ne!(vm.raw_jvm(), ptr::null_mut());
        }
    });
}
unsafe {
    assert_ne!(vm.raw_jvm(), ptr::null_mut());
}

The main purpose of JavaVM is to attach threads by provisioning JniEnv-s.

Implementations

impl JavaVM

pub fn create(arguments: &InitArguments) -> Result<Self, JniError>

Create a Java VM with the specified arguments.

Only one Java VM per process is supported. When called for the second time will return an error. This is the case even if the object is dropped.

JNI documentation

pub fn list() -> Result<Vec<Self>, JniError>

Get a list of created Java VMs.

JNI documentation

pub unsafe fn raw_jvm(&self) -> *mut JavaVM

Get the raw Java VM pointer.

This function provides low-level access to all of JNI and thus is unsafe.

pub fn attach( &self, arguments: &AttachArguments<'_>, ) -> Result<JniEnv<'_>, JniError>

Attach the current thread to the Java VM with a specific thread name. Returns a JniEnv instance for this thread.

JNI documentation

pub fn attach_daemon( &self, arguments: &AttachArguments<'_>, ) -> Result<JniEnv<'_>, JniError>

Attach the current thread to the Java VM as a daemon with a specific thread name. Returns a JniEnv instance for this thread.

JNI documentation

Trait Implementations

impl Debug for JavaVM

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for JavaVM

Make JavaVM be destroyed when the value is dropped.

JNI documentation

fn drop(&mut self)

Executes the destructor for this type.

impl Send for JavaVM

Make JavaVM sendable between threads. Guaranteed to be safe by JNI.

impl Sync for JavaVM

Make JavaVM shareable by multiple threads. Guaranteed to be safe by JNI.