a simple quiz on parseType(String)

[Marlene Miller]

A simple quiz: Which strings are valid as input?

class Test {
   public static void main(String[] args) {
      long l
      l = Long.parseLong("2");
      l = Long.parseLong("2L");
      float f;
      f = Float.parseFloat("2.0");
      f = Float.parseFloat("2f");
      f = Float.parseFloat("2d");
      double d;
      d = Double.parseDouble("2.0");
      d = Double.parseDouble("2f");
      d = Double.parseDouble("2d");
   }
} 

[Owee Nicolas]

Hi,
All the strings you specified are valid input. Please refer to the parseWrapperClass method of each of the Wrapper Class: Long, Floatand Double.
Hope that helps!
Owee

[Abhilash Vasudevan]

Oh, but I am getting a runtime exception in the l=Long.parseLong("2L") assignment, why?
Regards

[Shabbir Rahman]

I'm also getting same runtime exception. Why?

[Yogi Gupta]

Dear All,
Below is the javadoc comment for parseLong method:
Parses the string argument as a signed decimal long. The characters in the string must all be decimal digits, except that the first character may be an ASCII minus sign '-' (\u002D') to indicate a negative value. The resulting long value is returned, exactly as if the argument and the radix 10 were given as arguments to the parseLong(java.lang.String, int) method.
Note that neither the character L ('\u004C') nor l ('\u006C') is permitted to appear at the end of the string as a type indicator, as would be permitted in Java programming language source code.

Hope it is clear now.
Regards,
Yogesh

[Marlene Miller]

Thank you Yogesh. Here is what I was investigating:
1. Are type suffixes allowed, optional or prohibited?
It is invalid to use the long suffix.
It is okay to use the float or double suffix.
It is okay to specify a double (2d) in Float.parseFloat
It is okay to specify a float (2f) in Double.parseDouble
2. Does �2.0� mean double or does it mean either float or double?
It doesn�t matter, because both are acceptable to Float.parseFloat and Double.parseDouble.
3. The API doc for Float.parseFloat refers to Float.valueOf. The API doc for Float.valueOf refers to JLS 3.10.2. JLS 3.10.2 says a float literal must have a suffix. However, if you look at the source code for Float.valueOf, you will see that any of the following: no suffix f F d D is acceptable.
[ May 12, 2003: Message edited by: Marlene Miller ]