| 发表于：2007-08-28 11:04:121楼 得分:0 |
/**
* parses the string argument as a signed integer in the radix
* specified by the second argument. the characters in the string
* must all be digits of the specified radix （as determined by
* whether {@link java.lang.character#digit（char, int)} returns a
* nonnegative value), except that the first character may be an
* ascii minus sign <code> '- ' </code> （ <code> '\u002d ' </code> ) to
* indicate a negative value. the resulting integer value is returned.
* <p>
* an exception of type <code> numberformatexception </code> is
* thrown if any of the following situations occurs:
* <ul>
* <li> the first argument is <code> null </code> or is a string of
* length zero.
* <li> the radix is either smaller than
* {@link java.lang.character#min_radix} or
* larger than {@link java.lang.character#max_radix}.
* <li> any character of the string is not a digit of the specified
* radix, except that the first character may be a minus sign
* <code> '- ' </code> （ <code> '\u002d ' </code> ) provided that the
* string is longer than length 1.
* <li> the value represented by the string is not a value of type
* <code> int </code> .
* </ul> <p>
* examples:
* <blockquote> <pre>
* parseint（ "0 ", 10) returns 0
* parseint（ "473 ", 10) returns 473
* parseint（ "-0 ", 10) returns 0
* parseint（ "-ff ", 16) returns -255
* parseint（ "1100110 ", 2) returns 102
* parseint（ "2147483647 ", 10) returns 2147483647
* parseint（ "-2147483648 ", 10) returns -2147483648
* parseint（ "2147483648 ", 10) throws a numberformatexception
* parseint（ "99 ", 8) throws a numberformatexception
* parseint（ "kona ", 10) throws a numberformatexception
* parseint（ "kona ", 27) returns 411787
* </pre> </blockquote>
*
* @param s the <code> string </code> containing the integer
* representation to be parsed
* @param radix the radix to be used while parsing <code> s </code> .
* @return the integer represented by the string argument in the
* specified radix.
* @exception numberformatexception if the <code> string </code>
* does not contain a parsable <code> int </code> .
*/
public static int parseint（string s, int radix)
throws numberformatexception
{
if （s == null) {
throw new numberformatexception（ "null ");
}
if （radix < character.min_radix) {
throw new numberformatexception（ "radix " + radix +
" less than character.min_radix ");
}
if （radix > character.max_radix) {
throw new numberformatexception（ "radix " + radix +
" greater than character.max_radix ");
}
int result = 0;
boolean negative = false;
int i = 0, max = s.length（);
int limit;
int multmin;
int digit;
if （max > 0) {
if （s.charat（0) == '- ') {
negative = true;
limit = integer.min_value;
i++;
} else {
limit = -integer.max_value;
}
multmin = limit / radix;
if （i < max) {
digit = character.digit（s.charat（i++),radix);
if （digit < 0) {
throw numberformatexception.forinputstring（s);
} else {
result = -digit;
}
}
while （i < max) {
// accumulating negatively avoids surprises near max_value
digit = character.digit（s.charat（i++),radix);
if （digit < 0) {
throw numberformatexception.forinputstring（s);
}
if （result < multmin) {
throw numberformatexception.forinputstring（s);
}
result *= radix;
if （result < limit + digit) {
throw numberformatexception.forinputstring（s);
}
result -= digit;
}
} else {
throw numberformatexception.forinputstring（s);
}
if （negative) {
if （i > 1) {
return result;
} else { /* only got "- " */
throw numberformatexception.forinputstring（s);
}
} else {
return -result;
}
} | | |
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