Hi, The question is I have 2 Virtual Machines. SUN JVM and BEA JRockit. I am trying to use the SUN provided rt.jar with JRockit and vice-versa. But it dosen't work. It gives an UnsatisfiedLinkError, its not able to find the definition of a native method, whose name are canonicalize for SUN VM and canonicalize0 for JRockit. Any explanation why is it so. It gives the same error with -Xbootclasspath option as well. Does this implies that we always have to use the core Java APIs provided by the VM vendor. Do VMs load core APIs in an implementation specific manner or it's generic. Thanks in advance.