When should I call ReleaseStringUTFChars?

Note: When your native code is finished using the UTF-8 string, it must call ReleaseStringUTFChars . ReleaseStringUTFChars informs the VM that the native method is finished with the string so that the VM can free the memory taken by the UTF-8 string. Failing to call ReleaseStringUTFChars results in a memory leak.

What is local reference in Java?

Local references are scoped to their creating stack frame and thread, and automatically deleted when their creating stack frame returns. Global references allow native code to promote a local reference into a form usable by native code in any thread attached to the JVM.

How do I learn JNI?

Learning JNI

1. Create a Java Application.
2. Generate Header File via javah.
3. Create Implementation in C.
4. Compile the Implementation.
5. Run the Program.

What is JNI wrapper?

Java Native Interface, or JNI, is a standard mechanism for calling “native” code—that is, code compiled from a language such as C or C++—from within the Java Virtual Machine.

What is JNA and JNI?

Java Native Access (JNA) is a community-developed library that provides Java programs easy access to native shared libraries without using the Java Native Interface (JNI). JNA’s design aims to provide native access in a natural way with a minimum of effort. Unlike JNI, no boilerplate or generated glue code is required.

What is Jstring?

When a Java application passes a string to a native method, it passes the string as a jstring type. This jstring type is different from the regular C string type (char *). If your code tries to print a jstring directly, it will likely result in a VM crash.

How do you call a method in JNI?

You can call an instance method by following these three steps:

1. Your native method calls the JNI function GetObjectClass , which returns the Java class object that is the type of the Java object.
2. Your native method then calls the JNI function GetMethodID , which performs a lookup for the Java method in a given class.

What is reference VAR?

A reference variable is a variable that points to an object of a given class, letting you access the value of an object. An object is a compound data structure that holds values that you can manipulate. Instead, when you reference the reference variable, OpenROAD uses the values in the corresponding object.