"Integer" = variable name?

[Travis Benning]

Hi,
I got this question taking Jxam mock Exam:
Choose all valid variable names:
1) _int
2) %bob
3) $str
4) Integer
5) 2num
I put (1) and (3), but it also said (4) was correct.
Now I'm sure I'm sounding dumb asking this, but I thought that Integer was already a "taken" name.
Integer i = new Integer();
int i = Integer.parseInt("32");
If I'm wrong, it won't be the first time, but I'd like to please have this clarified asap.
All help is appreciated.
Thanks again,
Travis B.

[Manish Hatwalne]

I think you are right, only 1 and 3 seem to be the right answers.
HTH,
- Manish

[Graeme Brown]

The exam is correct, try compiling this:

Integer Integer = new Integer();
  

It will compile OK, but now you have the headache of trying to work out when you are referring to the class java.lang.Integer or to your local variable called Integer. Just because legally you can do something doesn't make it good practise to do so. That is why coding guidelines are so important.

[Valentin Crettaz]

Class names are valid names for identifiers...
try this:

public class Question59 {
  public static void main(String[] args) {
  String String = "String";//line 1
  int Question59 = 2;//line 2
  Object:for(int main=0;main<Question59*String.length();main+=Question59){ //line 3
     System.out.print(String.charAt(main)+" "); //line 4
     if(main>Question59)//line 5  
         break Object;//line 6
     }
   }
}

This code compiles and runs fine... Nothing prevents you to use class names for identifiers...
If you want more details, you can check out:
JLS 6.2 Names and Identifiers
JLS 3.8 Identifiers
[ February 26, 2002: Message edited by: Valentin Crettaz ]

[Dale DeMott]

What mock exam has this? I don't believe this is good practice and should not be posed as good practice!
-Dale

[Valentin Crettaz]

Dale,
you are right this is not a good practice to code like that, but this question is only to show that such coding practices are possible. You could use such a technique in a code obfuscator for instance which would replace identifiers with completely unrelated class names. That way it would be kind of difficult to figure out what the code does... Obfuscating the code is not a secure enough technique to protect your source code, though.
[ February 26, 2002: Message edited by: Valentin Crettaz ]

[Uday Kumar]

We should be able to use any word as identifier which does not figure in "keyword" and "reserve word" list in Java.

[Travis Benning]

Thanks ranchers!
I'm glad that I'm not alone thinking that this was a bit questionable.
Thanks for the clarification,
Travis B.

[Manish Hatwalne]

Originally posted by Travis Benning:
Thanks ranchers!
I'm glad that I'm not alone thinking that this was a bit questionable.
Thanks for the clarification,
Travis B.

I second that
- Manish