jnienv – Make Me Engineer

Keeping a global reference to the JNIEnv environment

June 13, 2023 by Tarik

You cannot cache the JNIEnv pointer. Read about it here: The JNI interface pointer (JNIEnv) is valid only in the current thread. Should another thread need to access the Java VM, it must first call AttachCurrentThread() to attach itself to the VM and obtain a JNI interface pointer. Once attached to the VM, a native … Read more

What is the best way to save JNIEnv*

July 4, 2022 by Tarik

Caching a JNIEnv* is not a particularly good idea, since you can’t use the same JNIEnv* across multiple threads, and might not even be able to use it for multiple native calls on the same thread (see http://android-developers.blogspot.se/2011/11/jni-local-reference-changes-in-ics.html) Writing a function that gets the JNIEnv* and attaches the current thread to the VM if necessary … Read more