RPN计算器 java代码

RPN计算器ProgramInputEachlineoftheinputfile(prob12.in)containsaseriesofnumbersandoperators.TheprogrammustevaluatetheselinesasRPNexpressions.Alltokensareseparatedbyoneormorespaces.Numbersmaybenegative.Validoperatorsare+(addition),-(subtraction),*(multiplication)and/(division).Thelastlin