The operator+is undefined for the argument type(s) java.math

The operator+is undefined for the argument type(s) java.math 在Java中这样报错The method SayHi() is undefined for the type AccpT The method IsEmpty(String) is undefined for the type The method getsession() is undefined for the type HttpServle The method selectAll() is undefined for the type productDaoI android The method getText() is undefined for the type R.str matlab?Input argument "a" is undefined. MATLAB:Input argument "x" is undefined matlab老是显示input argument '' is undefined MATLAB：Input argument "x" is undefined. matlab问题?Input argument 'X' is undefined. matlab ? Input argument "t" is undefined.