Richard Liang wrote:
Hello All,

When I'm trying to implement Scanner.nextInt(int radix), I met a problem.

As we all know, Character.MIN_RADIX equals 2 and Character.MAX_RADIX equals 36, so the parameter radix can not less than 2 or greater than 36, Otherwise that parameter is illegal.

But on RI, when the parameter radix is illegal, there are different kinds of Exception thrown.

   * If the parameter is less than 0 or greater than 36, RI throws a
     StringIndexOutOfBoundsException. Obviously this exception depends
     an RI's implementation.
   * If the parameter equals 1, RI throws an InputMismatchException
     with an additional information "The radix 1 is less than the
     Character.MIN_RADIX".
   * If the parameter equals 0, RI throws a
     java.util.regex.PatternSyntaxException whose constructor has three
     parameters. And the parameters depends on RI's implementation,
     that makes me can not follow RI.
Is this exception thrown by RegEx class? Should we identify at first if our regular expression has different behavior with RI on some certain input parameter?

And nothing is documented in the spec. Shall I follow RI's behavior? Thanks a lot.

Here is the test case to demo this issue.

public void test_nextIntI(){
      Scanner s = new Scanner("123 456");

      try {
           s.nextInt(-1);
           fail("Should throw StringIndexOutOfBoundsException");
       } catch (StringIndexOutOfBoundsException e) {
           // Expected
       }
       try {
           s.nextInt(0);
           fail("Should throw PatternSyntaxException");
       } catch (PatternSyntaxException e) {
           // Expected
       }
       try {
           s.nextInt(1);
           fail("Should throw InputMismatchException");
       } catch (InputMismatchException e) {
           // Expected
       }
       try {
           s.nextInt(40);
           fail("Should throw StringIndexOutOfBoundsException");
       } catch (StringIndexOutOfBoundsException e) {
           // Expected
       }
}



--
Paulex Yang
China Software Development Lab
IBM



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