Object model for java

Abstract

The mechanism includes three data structures: object data associated with each object O1, O2, O3 . . . of a program, a class descriptor associated with the classes to which the objects O1, O2, O3 . . . belong, and interface references. For each class C.sub.i, the class descriptor corresponding to the class C.sub.i includes: i) a class method table comprising one or more entries, wherein each entry identifies an implementation of a method inherited or defined by the class C.sub.i ; and ii) for each interface implemented by the class C.sub.i, an interface method table comprising one or more entries, wherein each entry identifies an implementation of a method declared by the particular interface or an implementation of a method declared by an interface extended by the particular interface. An interface reference for an interface declaration ID associated with a given object OI, wherein the object OI implements methods that are declared by an interface declaration ID includes a pointer to the interface method table corresponding to the interface declaration ID within the class descriptor corresponding to the object OI. An efficient mechanism for method invocations is provided by generating an index that identifies the entry corresponding to the appropriate method in the interface method table pointed to by the pointer of the interface reference, reading the data stored by the entry identified by the index, and controlling the computer processing apparatus to jump to the address identified by the data.