jclass | Go Java Class File Parser | Parser library

You have:

Using JNI, here is what worked for me that uses org.jdom.Element. My settings.xml file looks like this:

thisObject is a ExampleJNI not a Order so GetObjectClass will return ExampleJNI which doesn't have the constructor you are looking for. Change GetObjectClass to env->FindClass("Order").

You populate your array with three refetences to the same object. In the first loop the values of obj are changing on each iteration, that's why you get different values printed. Try to add the printing command

Note the section Implementing Local References from the JNI specification:

To implement local references, the Java VM creates a registry for each transition of control from Java to a native method. A registry maps nonmovable local references to Java objects, and keeps the objects from being garbage collected. All Java objects passed to the native method (including those that are returned as the results of JNI function calls) are automatically added to the registry. The registry is deleted after the native method returns, allowing all of its entries to be garbage collected.

The term “after the native method returns” means the reversal of the “transition of control from Java to a native method”, in other words, the method declared inside a Java class using the keyword native has been called and returns to the caller.

Once this is understood, it’s also clear how to read the Global and Local References section

Local references are valid for the duration of a native method call, and are automatically freed after the native method returns.

So when you have code that runs for a long time before returning to the Java caller or has no Java caller at all, there is no way around deleting references manually using DeleteLocalRef.

As Remy Lebeau mentioned, you can also use PushLocalFrame and PopLocalFrame to perform bulk destruction of references created between two points.

Mind that the destruction of the reference does not imply the destruction of the referenced object, but just not to prevent the garbage collection of the object. So after calling env -> CallBooleanMethod(list_obj, add_method, child_obj);, you can destroy the child_obj reference, because the object is still referenced by the list you’re referencing via list_obj, so the added object will be kept as long as it is still in use.

The problem is occurring because IPV4 and IPV6 have different sizes. Consider the following two lines of your code

The method you are trying to invoke is declared as get(String first, String... more). The variadic syntax in Java is just sugar for an array of the specified type, i.e. the two arguments of this method are really String and String[] -- which you correctly coded in the GetStaticMethodID call as (Ljava/lang/String;[Ljava/lang/String;).

So to call it you need two arguments: one String and one String[] (array) -- and (for your case) the array must contain zero elements, but such an empty array is not the same as NULL. Have a gander at NewObjectArray.

Yes, the documentation states

This array is valid until it is released by ReleaseStringUTFChars().

This is corroborated by the implementation in Hotspot, which just allocates off-heap memory for a copy.

This is a normal situation when some classes are loaded but not linked. You don't need to do anything to prepare classes manually - JVM does this automatically when needed. JVM Specification guarantees the classes is completely prepared before it is initialized. As soon as it happens, JVM TI ClassPrepare event is fired.

So in order to get all available jmethodIDs you'll need:

1. Iterate over all loaded classes, ignoring possible JVMTI_ERROR_CLASS_NOT_PREPARED.
2. Set ClassPrepare event callback and call GetClassMethods in it.