answer the question from scjp5.0

[nikunj thakur]

class Titanic {
public static void main(String[] args) {
Boolean bl = true;
boolean b2 = false;
boolean b3 = true;
if((bl & b2) | (b2 & b3) & b3)
System.out.print("alpha ");
if((bl = false) | (b1 & b3) | (bl | b2))
System.out.print("beta "};
}
}

What is the result?

beta

alpha

alpha beta

Compilation fails.

No output is produced.

An exception is thrown at runtime.
answer is exception is thrown at runtime
i want to ask can we have more than 2 expresions for the above operator

[abhishek pendkay]

did you run the program and see the exception..??? cause as far as i see the program should not throw any exception... it wont actually compile cause this

 System.out.print("beta "};   

you should close it with ) noot }... apart from that the program is fine
anyway please quote your sources so its also easier for us
[ November 26, 2007: Message edited by: abhishek pendkay ]

[Saroja Eshwar]

Hi nikunj,

The output you have given is wrong. It wont complile itself because of this line

System.out.print("beta "};

Need to close the paranthesis here...
System.out.print("beta ");

If this has been corrected then your code will compile but it wont give any output.

[Gosia Wittemann]

I did actually try to compile and run this example (after correcting the paretheses issue and variable names (sometimes it's b1 - B one, and sometimes bl - BL)) and I get following exception:

Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Type mismatch: cannot convert from boolean to Boolean

Of course, the easy solution is to make all variables primitive. But my question is why doesn't the compiler unbox the Boolean reference variable to a primitive?? I run it on Eclipse with Java 1.5

[nikunj thakur]

but i want to ask can put 3 expressions in for logical operators

[Gosia Wittemann]

nikunj, yes you can. After converting all variables to a primitive the code compiles, runs, just doesn't generate any output.

[Jared Cope]

Hi,

Originally posted by Gosia Wittemann:

Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Type mismatch: cannot convert from boolean to Boolean

After fixing the brackets and one's to el's (or vice-versa) boxing does indeed work for me. No need to convert everything to a primitive. Are you sure eclipse is compiling your code under 1.5? Check your preferences->Java->compiler setting.

Cheers, Jared.

P.S. There is no output.

[Gosia Wittemann]

Jared, thanks so much, that was the trick, I used the 1.5 JRE, but with 1.4 compliance
Anyway, searching for this bug made me install Eclipse Europa in the long last

[Bert Bates]

Hi Nikunj,

We're very happy that you're using our book to help you in your studies, and you are more than welcome to post mock questions from the book here in this forum for discussion. Speaking for myself and for all authors of mock exam questions, from now on, we need you to tell everyone the source of the mock exam question you're discussing.

Thanks,

Bert