rpnCalculator A starter spring boot application with CommandLineRunner is used, when application is started it accepts the inputs from user on the console.
A Unix like or CommandLineCalculator class injects a SimpleCalculator. This SimpleCalculator class is decoupled from its implementation of operators.
BaseArithmeticOperator abstract class declares four operators and SimpleArithmeticOperator extends to provide implementation. This allows for future operators.
##Trade-offs ##Solution/Design diagrams -- TBD ##Few more edge test cases can be added.