Reading From Standard Input?

I have to write sorting algorithm for numbers given on standard input(console) with following requirements:

The application must remember the distinction between double and integer numbers. This must be evident in the sorted output. Double type numbers are written using a period (.) to separate the fraction from the whole part.

The problem is I don't know how to efficiently distinct whether something is an int or double on standard input, to save them into 2 different arrays.

Only idea I've come to so far is to read each number as String and check if it has '.' character, to figure out if it's double and than convert it into right type and add it to correct array.

Also thought that maybe this would be achieveable using Pattern but how to do that?