If a type is boxed then it means that values of that type are represented by a pointer to a heap object. An unboxed type is represented by the value itself such as int, double, float, byte etc. Values of unboxed types appear only in the virtual machine's stack, registers, or as fields/elements of class/array instances.
The Jikes RVM also defines a number of other unboxed types. Due to a limitation of the way the compiler generates code the Jikes RVM must define an unboxed array type for each unboxed type. The unboxed types are;
Unboxed types may inherit from Object but they are not objects. As such there are some restrictions on the use of unboxed types:
org.vmmagic.unboxed.Addressshould be replaced with