An interview question I faced recently

[arulk pillai]

What gets printed for the following code snippet?

public class Binary7 {
public static void main(String[] args) {
System.out.println((int)(char)(byte)-1);
}
}

[Pushkar Choudhary]

Just checked in Eclipse and Java 6, got the output: 65535

Still trying to figure it out.

[arulk pillai]

 

Pushkar Choudhary wrote:Just checked in Eclipse and Java 6, got the output: 65535

Still trying to figure it out.

Start with, -1 in binary is represented as all 1's.

[Deepak Bala]

A bad question. Whether you get the answer right or wrong proves nothing.

I can understand why the answer is what it is, but the question is a waste of time.

[arulk pillai]

I will have to admit that there were other good questions. The interviewer clearly indicated that it was an optional question to ascertain how technical I was. He was also more interested in the approach.

[Jimmy Clark]

A poor question in my opinion. Not sure how it demonstrates how "technical" a person is. If the question was about recitation of numeric casting rules it might make more sense. But to ask someone what will get "printed" is a bit looney ... and a waste of time.

[Ninad Kulkarni]

Refer this also Java Puzzler book have explaination about it.

According to my way of thinking the process is as follows.

1111 1111 1111 1111 1111 1111 1111 1111 -1 (int) first step
1111 1111 -1 (byte) second step
1111 1111 1111 1111 1111 1111 1111 1111 -1 (int) third step
1111 1111 1111 1111 1 (char) fourth step
0000 0000 0000 0000 1111 1111 1111 1111 65535

first step is narrowing primitive conversions
second step + third step is widening & then narrowing primitive conversions
fourth step is widening primitive conversions

[Luke Kolin]

 

James Clarks wrote:A poor question in my opinion. Not sure how it demonstrates how "technical" a person is.

Agreed. Obscure Java trivia questions (unless one is implementing a JVM themselves) speak far more about the interviewer than the candidate.

Cheers!

Luke

[Deepak Bala]

 

Ninad Kulkarni wrote:Refer this also Java Puzzler book have explaination about it.

According to my way of thinking the process is as follows.

1111 1111 1111 1111 1111 1111 1111 1111 -1 (int) first step
1111 1111 -1 (byte) second step
1111 1111 1111 1111 1111 1111 1111 1111 -1 (int) third step
1111 1111 1111 1111 1 (char) fourth step
0000 0000 0000 0000 1111 1111 1111 1111 65535

first step is narrowing primitive conversions
second step + third step is widening & then narrowing primitive conversions
fourth step is widening primitive conversions

If it was stolen from the java puzzler book, thats even worse

[Ninad Kulkarni]

@Deepak

If it was stolen from the java puzzler book, thats even worse

All credit goes to authors of the Java Puzzlers book for this question already in java puzzle list in their book.
I given example of binary numbers to understand multiple cast process easily in the given question by using JLS3.0.

[Deepak Bala]

Ninad, I was not referring to you in my last post, I was referring to the person who took the interview. Just wanted to clarify that

[Ninad Kulkarni]

Thanks Deepak for clarification. Now I got your point.