1. A data processing device comprising: a processor comprising: a code storage unit which stores an original code to be translated into a machine language code; a code analyzer which analyzes the original code stored in the code storage unit; a register allocator which allocates a predesignated register to each stack slot of an operand stack of Java virtual machine for all of an original code, based on a result of the analysis by the code analyzer; and a code executor which generates a machine language code for all of the original code using the register allocated by the register allocator, and wherein the allocating the predesignated register and the generating the machine language code are performed at a same period of time; and wherein a time for the register allocator to allocate the predesignated register is not included in a time for the data processing device to translate the original code into the machine language code.