java.io.StreamTokenizer.TT_NUMBER: Floating or Integer ?

Question

Hi all is there a way to find if the value parsed and returned by java.io.StreamTokenizer.nval (e.g. 200) was an integer or a floating number ?

Thanks

Edited:

I want to be able to know if the input was '200' or '200.0'.

Answer 1

I would use the modulus operator:

if (yourNval % 1 > 0)
{
    // nval is floating point.
}
else
{
    // nval is an integer.
}

This works because modulus works with floating point numbers in Java as well as integers.

UPDATE: Since you specify a need to distinguish integers from doubles with zero-value decimal portions, I think you'll have to do something like the following:

Double(yourNval).toString().indexOf('.');

So a more-complete function will look like:

if (yourNval % 1 > 0)
{
    // nval is floating point.
}
else
{
    // nval is an integer.

    // Find number of trailing zeroes.
    String doubleStr = Double(yourNval).toString();
    int decimalLoc = doubleStr.indexOf('.');
    int numTrailingZeroes = 0;

    if (decimalLoc > 0)
    {
        numTrailingZeroes = doubleStr.length() - decimalLoc - 1;
    }
}

Answer 2

As you are essentially trying to figure out if a double is an int or not, you can create a BigDecimal and test its scale() method. You could also use the Math static method floor() and test the return value against the original.

 if(Math.floor(myStreamTokenizer.nval) == myStreamTokenizer.navl)) {
     //treat it as an int
 } else {
     //treat it as a double
 }

Of the two, I would use the Math.floor option, as it would be more efficient.

Answer 3

I don't think it is possible with StringTokenizer, it's too old. You can use Scanner to do the job:

Scanner fi = new Scanner("string 200 200.0");
fi.useLocale(Locale.US);

while (fi.hasNext()) {
    if (fi.hasNextInt()) {
        System.out.println("Integer: " + fi.nextInt());
    } else if (fi.hasNextDouble()) {
        System.out.println("Double: " + fi.nextDouble());
    } else {
        System.out.println("String: " + fi.next());
    }  
}

Documentation for the class is here