The common practice in supporting Java interfaces is to use interface tables (itables); we refer the reader to the work of Alpern et al. [2] for a discussion of the prior implementation techniques for interface dispatch and an efficient implementation of Java interfaces. For each interface that a class implements, there is a corresponding itable which contains all the methods declared in the interface. At run time, an interface method invocation would involve looking up the itable by interface name, fetching the address of the interface method from a fixed offset, determined at compile time, and invoking it. The itable look-up mechanism provides natural support for binary compatibility; however, if the method layout of an itable may change, it would be wrong to use a fixed offset to access an interface method.
Fortunately, this is exactly the same problem that we solved for virtual methods and vtable dispatch. All we have to do is make sure interface method invocations go through the offset table, and fill in the offset table incrementally at class loading time once the itable layout is determined.