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  1. JDK
  2. JDK-4240898

JNI specification of NewObject[A,V] talks about an impossible situation

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      Name: dkC59003 Date: 05/25/99



      JNI specification says that NewObject[A,V] can throw InstantiationException
      if class argument is an interface. But this situation is impossible
      because an interface can't have <init> method that required to be passed
      as 3rd argument to NewObject[A,V]

      The section "JNI Functions" of JNI spec says about function NewObjectV:

      -----spec-----
      "jobject NewObjectV(JNIEnv *env, jclass clazz, jmethodID methodID, va_list args);

      Constructs a new Java object. The method ID indicates which constructor method
      to invoke. This ID must be obtained by calling GetMethodID() with <init> as the
      method name and void (V) as the return type.

      Programmers place all arguments that are to be passed to the constructor in an
      args argument of type va_list that immediately follows the methodID argument.
      NewObjectV() accepts these arguments, and, in turn, passes them to the Java
      method that the programmer wishes to invoke.

      PARAMETERS:
      env: the JNI interface pointer.
      clazz: a Java class object.
      methodID: the method ID of the constructor.
      args: a va_list of arguments to the constructor.

      RETURNS:
      Returns a Java object, or NULL if the object cannot be constructed.

      THROWS:
      InstantiationException: if the class is an interface or an abstract class."
      -----spec-----

      But valid interface class file cannot contain a constructor. And therefore
      a method ID of method <init> cannot be obtained for interface, valid
      parameters cannot be passed to function NewObjectV and InstantiationException
      cannot be thrown as effect of an attempt to constructe a interface object.
      So JNI specification describes an impossible situation.

      Same reasons are applicable for functions NewObject, NewObjectA.

      ======================================================================

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            • Assignee:
              abuckley Alex Buckley
              Reporter:
              dkhukhrosunw Dmitry Khukhro (Inactive)
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