Add new isjava function. * libinterp/octave-value/ov-base.h: Add new virtual function is_java (). Returns false. libinterp/octave-value/ov-java.h: Overload virtual function is_java to return true for objects in class octave_java. libinterp/octave-value/ov.h: Add is_java function that calls objects is_java function. * libinterp/octave-value/ov-java.cc: Add new DEFUN (isjava) which uses is_java. Placed outside HAVE_JAVA ifdef so that it is always available.

--- a/libinterp/octave-value/ov-base.h
+++ b/libinterp/octave-value/ov-base.h
@@ -365,6 +365,8 @@
 
   virtual bool is_object (void) const { return false; }
 
+  virtual bool is_java (void) const { return false; }
+
   virtual bool is_cs_list (void) const { return false; }
 
   virtual bool is_magic_colon (void) const { return false; }