Systems, methods, and computer products for automated injection of java bytecode instructions for java load time optimization via runtime checking with upcasts

Automated injection of Java bytecode instructions for Java load time optimization via runtime checking with upcasts. Exemplary embodiments include a method including generating a stack for each of a plurality of bytecodes, generating a subclass configured to keep a history of instructions that have modified the stack, statically scanning a plurality of Java classes associated with the plurality of bytecodes to locate class file configurations and bytecode patterns that cause loading of additional classes to complete a verification of each of the classes in the plurality of Java classes, rewriting the bytecodes to delay the loading of the additional classes until required at a runtime, recording modifications that have been made to the stack by the instructions, and applying the modifications to each of the bytecodes in the plurality of bytecodes.