An apparatus, method and article of manufacture tangibly embodying computer readable instructions for optimizing a Java object on a target computer program. The apparatus includes: a storage unit for storing a value of the object and management information on the object in association with each other; a code generation unit for generating, from the target computer program, optimized code and unoptimized code; a switching unit for switching from executing the target computer program using the optimized code to executing the target computer program using the unoptimized code in response to an event in which the value of the object is written while the target computer program is executed by using the optimized code; and a management unit for managing the object by accessing the management information by a non-detection write operation in which writing to the object is performed without being detected.