How to check entered value is of which primitive type?

[Naresh BabuP]

Hello,

How to check entered value is of which primitive type? Say, entered value is from command prompt.

regards,
Naresh

[Christophe Verré]

Before thinking of anything, which primitive would you say "0" is ?

[Nishan Patel]

In that case you can make Regex pattern and check if contains only number form [0-9] means int. If contains Alphabet from [A-Za-z0-9] and other special character then String. If input contains [0-9] with (DOT .) then float. you can set it according to your requirement.

[Rob Spoor]

Important question: what is "0"? Is it:
a) a byte
b) a short
c) a char
d) an int
e) a long
f) a float
g) a double
h) all of the above

These kinds of decisions are very important; do you always take int if possible, ignoring byte and short? Is char only every 1-character String that is not a digit?

[Ireneusz Kordal]

Use Scanner:

        String s = "5 test true 2.54 af2";
        Scanner sc = new Scanner(s);

        while(sc.hasNext()){
            if(sc.hasNextInt()){
                System.out.println("Integer = " + sc.nextInt());
            }else             if(sc.hasNextDouble()){
                System.out.println("Double = " + sc.nextDouble());
            }
            else if(sc.hasNextBoolean()){
                System.out.println("Boolean= " + sc.nextBoolean());
            }else { // String
                System.out.println("Text= " + sc.next());
            }
        }    

[Campbell Ritchie]

Somebody else had a similar question recently: here.