find decimal in a given number

How can i find decimal(dot) in a given number in java.

I am getting input from user, he may give intege开发者_开发知识库r or float value.

I need to find he entered integer or float, is it possible?

if yes could u tell me please.

-- Thanks

Assuming you got the digits of the number in a String, it would be

String number = ...;
if (number.indexOf('.') > -1)
  ...

you can try with yourNumberString.indexOf("."). If it returns a number greater than -1 there's a dot in the input.

Anticipating your need, I would suggest that you use java.util.Scanner for number parsing, and use its hasNextXXX methods instead of dealing with parseInt etc and deal with NumberFormatException.

    import java.util.*;

    String[] inputs = {
        "1",
        "100000000000000",
        "123.45",
        "blah",
        "  "
    };
    for (String input : inputs) {
        Scanner sc = new Scanner(input);
        if (sc.hasNextInt()) {
            int i = sc.nextInt();
            System.out.println("(int) " + i);
        } else if (sc.hasNextLong()) {
            long ll = sc.nextLong();
            System.out.println("(long) " + ll);
        } else if (sc.hasNextDouble()) {
            double d = sc.nextDouble();
            System.out.println("(double) " + d);
        } else if (sc.hasNext()) {
            System.out.println("(string) " + sc.next());
        }
    }

This prints:

(int) 1
(long) 100000000000000
(double) 123.45
(string) blah

You do not need to explicitly search for the location of the decimal point as some answers suggest. Simply parse the String into a double and then check whether that double represents an integer value. This has the advantage of coping with scientific notation for doubles; e.g. "1E-10", as well as failing to parse badly formatted input; e.g. "12.34.56" (whereas searching for a '.' character would not detect this).

String s = ...
Double d = new Double(s);
int i = d.intValue();

if (i != d) {
  System.err.println("User entered a real number.");
} else {
  System.err.println("User entered an integer.");
}

Some other ways to do this:

given

String input = ...

the following evaluates to true if it's a decimal number

input.split(".").length == 2

or

input.matches(".+\\..+")

or

!input.matches("\\d+")