nconstantsis created and assigned to a field in the class.
constant_poolis set to point to a dynamically allocated array which indicates which fields in the constant_pool have already been resolved.
constant_pool[nconstants - 1]are set to point at the "type" field that corresponds to this constant item.
When an instruction is executed that references the constant pool, an index is generated, and
constant_pool is checked to see if the index has already been resolved. If so, the value of
constant_pool[index] is returned. If not, the value of
constant_pool[index] is resolved to be the actual pointer or data, and overwrites whatever value was already in