Run the following program. It shows that for the really big long value
given, conversion to float using Float.valueOf() differs from the value
of converting the same string to a Long, then casting to a float.
I believe that the latter process gives the correct answer, where the
former is wrong in the least significant bit.

class doubleRoundBug {
    /*
     * try to demonstrate input error caused
     * by double rounding.
     */
    static String instring = "18014399583223809";

    public static void main( String ignore[] ){
long lval = Long.valueOf( instring).longValue();
float f1 = Float.valueOf( instring).floatValue();
float f2 = (float)lval;
if ( f1 == f2 ){
System.out.println("OK");
} else {
System.out.println("String "+instring+" =>"+f1 );
System.out.println("Long "+lval+" =>"+f2 );
System.out.println(f1+" != "+f2);
}
    }
}

Output is:

String 18014399583223809 =>1.80143985E16
Long 18014399583223809 =>1.80144007E16
1.80143985E16 != 1.80144007E16

richard.tuck@Eng 1997-08-11